A service transmission system and method based on heterogeneous network deployment

Abstract

The present invention discloses a service transmission system and method based on heterogeneous network deployment, wherein the service transmission system based on heterogeneous network deployment includes: a broadcast tower and multiple cellular base stations located within the coverage of the broadcast tower; the broadcast tower is used to undertake the broadcast services of terminal users within the coverage whose moving speed is less than or equal to a preset speed, and the broadcast services of terminal users within the preset range of the broadcast tower and whose moving speed is greater than the preset speed; the multiple cellular base stations are used to undertake the broadcast services of other terminal users within the coverage. By adopting the present invention, a service transmission system composed of a broadcast tower and a cellular base station is established, and service transmission is carried out through the cooperation between the broadcast tower and the cellular base station, which not only meets the coverage of terrestrial broadcast services, but also improves the service transmission quality for terminal users moving at high speed in the area, thereby improving the user experience of terminal users.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a service transmission system and method based on heterogeneous network deployment. Background Art

[0002] With the development of society and the advancement of science and technology, communication technology, as an important way to transmit and obtain information, plays an important role in the process of informatization. People's demand for communication quality and data transmission rate is also increasing. However, wireless communication networks have always been constrained by channel capacity and spectrum resources.

[0003] Among the existing wireless communication networks, there are broadcast networks that provide services in a broadcasting manner, such as the European Digital Video Broadcasting (DVB) network. Traditional broadcast networks send signals through high-power high tower (HPHT) broadcasts, which have the advantages of wide coverage and high spectrum utilization, but cannot effectively transmit services to high-speed mobile terminal users in the area, nor do they have the ability to provide user feedback and interaction, and cannot transmit unicast services to terminal users. Therefore, how to improve the transmission quality of broadcast services, increase the types of service transmission, and maximize the utilization of transmission resources has become the biggest problem. Summary of the invention

[0004] The present invention provides a service transmission system and method based on heterogeneous network deployment, which are used to at least solve the problem in the prior art that high-speed mobile terminal customers cannot obtain high-quality transmission services.

[0005] According to a first aspect of the present invention, a service transmission system based on heterogeneous network deployment includes: a broadcast tower and a plurality of cellular base stations located within the coverage area of ​​the broadcast tower;

[0006] The broadcast tower is used to undertake the broadcast services of terminal users within the coverage area whose moving speed is less than or equal to the preset speed, and the broadcast services of terminal users within the preset range from the broadcast tower whose moving speed is greater than the preset speed;

[0007] The multiple cellular base stations are used to undertake broadcast services for other terminal users within the coverage area.

[0008] According to some embodiments of the present invention, the plurality of cellular base stations are further configured to undertake multicast services for all terminal users within the coverage area.

[0009] According to some embodiments of the present invention, the multiple cellular base stations are also used to undertake unicast services for all terminal users within the coverage area.

[0010] According to some embodiments of the present invention, the service transmission system based on heterogeneous network deployment further includes:

[0011] The control system is used to control the transmission rates of the broadcast service and the multicast service to be minimum so as to maximize the transmission rate of the unicast service.

[0012] According to some embodiments of the present invention, the control system is used to:

[0013] Calculating a minimum transmission rate corresponding to a first carrier bandwidth of the broadcast tower, where the first carrier bandwidth is used to bear broadcast services of terminal users within the coverage area whose moving speed is less than or equal to a preset speed;

[0014] Calculating a minimum transmission rate corresponding to a second carrier bandwidth of the broadcast tower, where the second carrier bandwidth is used to bear broadcast services of terminal users within a preset range from the broadcast tower and whose moving speed is greater than a preset speed;

[0015] Calculating a minimum transmission rate of the broadcast tower broadcast service based on a minimum transmission rate corresponding to the first carrier bandwidth and a minimum transmission rate corresponding to the second carrier bandwidth;

[0016] respectively calculating a minimum transmission rate corresponding to a broadcast service and a minimum transmission rate corresponding to a multicast service of the cellular base station;

[0017] Based on the minimum transmission rate of the broadcast tower broadcast service, the minimum transmission rate corresponding to the cellular base station broadcast service, and the minimum transmission rate corresponding to the cellular base station multicast service, the maximum value of the cellular base station unicast service transmission rate is calculated.

[0018] A service transmission method based on heterogeneous network deployment according to an embodiment of the second aspect of the present invention includes:

[0019] Setting a broadcast tower, the broadcast tower is used to undertake the broadcast services of terminal users whose moving speed is less than or equal to a preset speed within the coverage area, and the broadcast services of terminal users whose moving speed is greater than the preset speed within a preset range from the broadcast tower;

[0020] A plurality of cellular base stations are set up, and the plurality of cellular base stations are all located within the coverage area, and the plurality of cellular base stations are used to undertake broadcast services for other terminal users within the coverage area.

[0021] According to some embodiments of the present invention, the plurality of cellular base stations are further configured to undertake multicast services for all terminal users within the coverage area.

[0022] According to some embodiments of the present invention, the multiple cellular base stations are also used to undertake unicast services for all terminal users within the coverage area.

[0023] According to some embodiments of the present invention, the method further comprises:

[0024] The transmission rates of the broadcast service and the multicast service are controlled to be minimum so as to maximize the transmission rate of the unicast service.

[0025] According to some embodiments of the present invention, controlling the transmission rates of the broadcast service and the multicast service to be minimum so as to maximize the transmission rate of the unicast service includes:

[0026] Calculating a minimum transmission rate corresponding to a first carrier bandwidth of the broadcast tower, where the first carrier bandwidth is used to bear broadcast services of terminal users within the coverage area whose moving speed is less than or equal to a preset speed;

[0027] Calculating a minimum transmission rate corresponding to a second carrier bandwidth of the broadcast tower, where the second carrier bandwidth is used to bear broadcast services of terminal users within a preset range from the broadcast tower and whose moving speed is greater than a preset speed;

[0028] Calculating a minimum transmission rate of the broadcast tower broadcast service based on a minimum transmission rate corresponding to the first carrier bandwidth and a minimum transmission rate corresponding to the second carrier bandwidth;

[0029] respectively calculating a minimum transmission rate corresponding to a broadcast service and a minimum transmission rate corresponding to a multicast service of the cellular base station;

[0030] Based on the minimum transmission rate of the broadcast tower broadcast service, the minimum transmission rate corresponding to the cellular base station broadcast service, and the minimum transmission rate corresponding to the cellular base station multicast service, the maximum value of the cellular base station unicast service transmission rate is calculated.

[0031] By adopting the embodiment of the present invention, a service transmission system consisting of a broadcast tower and a cellular base station is established within the coverage area. Through the collaborative service transmission between the broadcast tower and the cellular base station, the coverage of the terrestrial broadcast service is met, and the service transmission quality for high-speed mobile terminal users in the area is improved.

[0032] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Various other advantages and benefits will become apparent to those skilled in the art by reading the detailed description of the embodiments below. The accompanying drawings are only used to illustrate the preferred embodiments and are not to be considered as limiting the present invention. In the accompanying drawings:

[0034] Figure 1 It is a structural diagram of a service transmission system based on heterogeneous network deployment in an embodiment of the first aspect of the present invention;

[0035] Figure 2 It is a structural diagram of a service transmission system based on heterogeneous network deployment in an embodiment of the first aspect of the present invention;

[0036] Figure 3 is a schematic diagram of the division of the carrier bandwidth of a broadcast tower in an embodiment of the first aspect of the present invention;

[0037] Figure 4 is a schematic diagram of the division of carrier bandwidth of a cellular base station in an embodiment of the first aspect of the present invention;

[0038] Figure 5 It is a schematic diagram of a process for calculating the optimal power allocation for unicast services in a service transmission system based on heterogeneous network deployment in an embodiment of the first aspect of the present invention. DETAILED DESCRIPTION

[0039] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0040] The first embodiment of the present invention proposes a service transmission system based on heterogeneous network deployment, referring to Figure 1 , including: a broadcast tower and a plurality of cellular base stations located within the coverage area of ​​the broadcast tower. For example, the plurality of cellular base stations are arranged around the broadcast tower. The number of broadcast towers can be set to one or more according to the actual scenario.

[0041] The broadcast tower is used to undertake broadcast services for terminal users within the coverage area whose moving speed is less than or equal to a preset speed. The broadcast tower can also undertake broadcast services for terminal users within a preset range from the broadcast tower whose moving speed is greater than a preset speed.

[0042] For example, refer to Figure 3 , corresponding to the access criteria for broadcast service transmission signals. Set the broadcast tower to work at a carrier frequency of 600 MHZ, and divide the bandwidth occupied by the broadcast tower into the first carrier bandwidth BWP1 H With the second carrier bandwidth BWP2 H . Set BWP1 H The subcarrier spacing is Cyclic prefix Setting up BWP2 H The subcarrier spacing is Cyclic prefix The preset speed is 67.5km / h and the preset range is 10km. When the terminal user is within the coverage of the broadcast tower, its position remains unchanged or its speed is less than or equal to 67.5km / h, the terminal user is connected to the BWP1. H The carrier bandwidth is used for broadcast service transmission. When the end user is less than 10 km from the broadcast tower and the moving speed is greater than 67.5 km / h and less than 250 km / h, the end user is connected to BWP2. H The carrier bandwidth is used for broadcast service transmission.

[0043] The multiple cellular base stations are used to undertake broadcast services for other terminal users within the coverage area.

[0044] For example, refer to Figure 4 , set the cellular base station to operate at a carrier frequency of 700MHZ, and set the carrier bandwidth of the cellular base station broadcast service to The subcarrier spacing is Δf L =15kHz. When the distance between the terminal user and the broadcast tower is greater than 10km and the moving speed is greater than 67.5km / h and less than 250km / h, the terminal user is connected to the cellular base station. Carry out broadcast service transmission.

[0045] According to the embodiment of the present invention, a service transmission system consisting of a broadcast tower and a cellular base station is established, and the broadcast tower and the cellular base station cooperate to transmit broadcast services, and the broadcast signal of the broadcast tower or the cellular base station is selectively received according to the location and movement speed of the terminal user. This not only satisfies the coverage of the terrestrial broadcast service, but also improves the transmission quality of the broadcast service in the area.

[0046] On the basis of the above-mentioned embodiments, various variant embodiments are further proposed. It should be noted that, in order to make the description concise, only the differences from the above-mentioned embodiments are described in each variant embodiment.

[0047] According to some embodiments of the present invention, the plurality of cellular base stations are further configured to undertake multicast services for all terminal users within the coverage area.

[0048] For example, refer to Figure 4 , set the cellular base station to operate at a carrier frequency of 700MHZ, and set the carrier bandwidth of the cellular base station multicast service to The subcarrier spacing is Δf L =15kHz. For multicast services of terminal users within the coverage area, the terminal users are connected to BWP2. L The carrier bandwidth is used for multicast service transmission, thus realizing the multi-service joint transmission of the service transmission system.

[0049] According to some embodiments of the present invention, the multiple cellular base stations are also used to undertake unicast services for all terminal users within the coverage area.

[0050] For example, refer to Figure 4 , set the cellular base station to operate at a carrier frequency of 700MHZ, and set the carrier bandwidth of the unicast service of the cellular base station to The subcarrier spacing is Δf L =15kHz. For unicast services of terminal users within the coverage area, the terminal users are connected to BWP3. L The carrier bandwidth part is used for unicast service transmission, thus realizing multi-service joint transmission of the service transmission system.

[0051] According to some embodiments of the present invention, the service transmission system based on heterogeneous network deployment further includes:

[0052] The control system is used to control the transmission rates of the broadcast service and the multicast service to be minimum so as to maximize the transmission rate of the unicast service.

[0053] Specifically, in some embodiments of the present invention, the control system is used to:

[0054] Calculating a minimum transmission rate corresponding to a first carrier bandwidth of the broadcast tower, where the first carrier bandwidth is used to bear broadcast services of terminal users within the coverage area whose moving speed is less than or equal to a preset speed;

[0055] Calculating a minimum transmission rate corresponding to a second carrier bandwidth of the broadcast tower, where the second carrier bandwidth is used to bear broadcast services of terminal users within a preset range from the broadcast tower and whose moving speed is greater than a preset speed;

[0056] Calculating a minimum transmission rate of the broadcast tower broadcast service based on a minimum transmission rate corresponding to the first carrier bandwidth and a minimum transmission rate corresponding to the second carrier bandwidth;

[0057] respectively calculating a minimum transmission rate corresponding to a broadcast service and a minimum transmission rate corresponding to a multicast service of the cellular base station;

[0058] Based on the minimum transmission rate of the broadcast tower broadcast service, the minimum transmission rate corresponding to the cellular base station broadcast service, and the minimum transmission rate corresponding to the cellular base station multicast service, the maximum value of the cellular base station unicast service transmission rate is calculated.

[0059] For example, refer to Figure 5According to the specific actual scenario, the subcarrier spacing between the broadcast tower and the cellular base station is set to ensure that the broadcast signal of the service transmission system composed of the broadcast tower and the cellular base station can cover the corresponding scenario area, and the optimal power allocation value of the broadcast tower is calculated to maximize the minimum transmission rate of the broadcast service of the broadcast tower. Then, according to the actual scenario, the minimum transmission rate of the multicast service of the cellular base station is set or calculated, and finally the optimal power allocation value of the unicast service of the cellular base station is determined to configure its maximum transmission rate. The reasonable allocation of resources by the service transmission system is guaranteed.

[0060] In some examples of the present invention, the control system for controlling the maximum transmission rate of the unicast service includes:

[0061] refer to Figure 3 , the bandwidth occupied by the broadcast tower is divided into subcarriers with a spacing of The cyclic prefix is The first carrier bandwidth BWP1 H With subcarrier spacing of The cyclic prefix is The second carrier bandwidth BWP2 H .

[0062] refer to Figure 4 , the bandwidth occupied by the cellular base station is divided into subcarriers with a spacing of Δf L = 15kHz third carrier bandwidth Fourth carrier bandwidth and the fifth carrier bandwidth

[0063] When terminal user k receives broadcast services, he needs to k and speed v k Selectively access broadcast service resources from broadcast towers and cellular base stations. If the terminal user's mobile speed v k ≤67.5km / h, then connect to the broadcast tower BWP1 H Carrier bandwidth part. If the terminal user's moving speed is 67.5km / h<v k ≤250km / h, and in area l k ∈Cor near ,Cor near If the distance to the broadcast tower is less than or equal to 10 km, then access the broadcast tower BWP2 H Carrier bandwidth part. If the terminal user's moving speed is 67.5km / h<v k ≤250km / h, and in area l k ∈Cor edge ,Cor edge If the distance from the broadcast tower is greater than 10 km, then access Coredge BWP1 for the cellular network broadcasting service portion within the region L Carrier bandwidth. For receiving multicast services, the terminal user determines the location l k and moving speed v k , select the multicast service carrier bandwidth portion BWP2 corresponding to the adjacent cellular base station L , realizing multi-base station joint transmission. For receiving unicast services, the terminal user selects the carrier bandwidth part BWP3 of the nearest cellular base station to access. L , and remove interference from adjacent base stations on the same subcarrier.

[0064] The first broadcast service signal of the broadcast tower received by the terminal user in the first carrier bandwidth is calculated based on the first carrier bandwidth occupied by the broadcast tower, the power allocated by the broadcast tower to the first carrier bandwidth, and the subcarrier spacing of the first carrier bandwidth occupied by the broadcast tower.

[0065] In this embodiment, the number of broadcast towers is F H , the broadcast tower set is represented as The number of terminal users in the service transmission system is K, and the terminal user set is expressed as The set of broadcast towers whose signals transmitted to end user k are within the multipath delay range of the broadcast towers is expressed as The set of end users accessing the broadcast tower BWP1 is represented as The set of end users accessing the broadcast tower BWP2 is represented as In Cor near The set of end users in scope is represented as The broadcast tower uses a single antenna to transmit broadcast services. The end user receiving end is a single antenna. The transmission bandwidth of the broadcast tower is w H The bandwidth occupied by the first carrier bandwidth BWP1 is represented by α1w H , the subcarrier spacing is The number of subcarriers in the BWP1 part is The BWP1 partial subcarrier set can be The bandwidth occupied by the second carrier bandwidth BWP2 is represented by α2w H , the subcarrier spacing is The number of subcarriers in the BWP2 part is The BWP2 partial subcarrier set can be Indicates the broadcast tower f H and the channel parameters of end user k on subcarrier n, Indicates broadcasting Tata f H The BWP1 part carries the broadcast service information on subcarrier n. Indicates the broadcast tower f HThe broadcast service information carried on subcarrier n in the BWP2 part, Indicates the broadcast tower f H The power allocated to the broadcast service on the first carrier bandwidth BWP1, Indicates that The power allocated to subcarrier n satisfies Similarly, Indicates the broadcast tower f H The power allocated to the broadcast service on the second carrier bandwidth BWP2, Indicates that The power allocated to subcarrier n satisfies Broadcast Tower H The power allocated to BWP1 and the power allocated to BWP2 need to be no greater than the total transmission power of the broadcast tower, that is, The broadcast towers in the system use the same power allocation scheme on each subcarrier.

[0066] The channel between broadcast tower f and user k on subcarrier n can be expressed as:

[0067]

[0068] in represents the channel between base station f and user k on subcarrier n, Is a scalar, indicating the channel Path loss and shadow fading, where PL represents the path loss, and its value is based on the spatial field strength distribution given in ITU-RP.1546-6 [6], σ sh Indicates channel The standard deviation of the shadow fading, σ sh =5.5dB[7]. It represents small-scale fading and conforms to a complex Gaussian distribution with a mean of 0 and a variance of 1.

[0069] In the system, N0 represents the unilateral power spectrum density of white noise.

[0070] N0=k×T×NF(W / Hz)

[0071] where k = 1.381*10 -23 J / K represents the Boltzmann constant, T represents the absolute temperature of noise, and here we assume that the temperature is T = 290K (16.85°C), and NF represents the noise factor, and here we take NF = 6dB[7].

[0072] Broadcast Tower H At the transmitting end, the same broadcast service information is carried in the two carrier bandwidth parts BWP1 and BWP2 respectively. The transmitting end can be:

[0073]

[0074]

[0075] in The main diagonal is Dimension, represents the signal power carried by each subcarrier in the BWP1 part, Indicates the broadcast service information carried on each subcarrier of the BWP1 part of the broadcast tower. The main diagonal is Dimension, represents the signal power carried by each subcarrier in the BWP2 part, Indicates the broadcast service information carried on each subcarrier of the BWP2 part of the broadcast tower.

[0076] Within the coverage area of ​​the broadcast tower, if the terminal user k has a speed v k ≤v1, v1=67.5km. Then access BWP1, the subcarrier spacing is Because the transmission power of the broadcast tower is large, the terminal user can receive the signals transmitted by multiple broadcast towers and perform signal diversity reception. The terminal user k is in the subcarrier The first broadcast service signal received on the

[0077]

[0078] The first term in the formula represents the end user k in the subcarrier The second term is the signal sent by the end user k in the subcarrier Signals received on the network that are not within the multipath delay range of the base station's transmitted signal are considered interference. Indicates that the subcarrier The noise received on the surface has a mean of 0 and a variance of independent complex Gaussian random variables that satisfy Indicates that the noise satisfies the mean of 0 and the variance is is a complex Gaussian distributed random variable, and N0 represents the unilateral power spectral density of the noise.

[0079] A signal to interference and noise ratio of the first broadcast service signal is calculated based on the first broadcast service signal.

[0080] End user k in subcarrier The signal-to-interference-to-noise ratio of the broadcast service received on the CAN bus can be expressed as:

[0081]

[0082] The first term in the denominator Indicates that the subcarrier from the adjacent cell The signal sent to user k that is not within the multi-path delay range of the transmitted signal is regarded as interference and is expressed as:

[0083]

[0084] The second term in the denominator It represents the inter-carrier interference caused by the high-speed movement of the terminal to the receiving end. Here, the influence of Doppler frequency shift on the receiving end is quantified. d,max Indicates the maximum Doppler generated by the high-speed movement at the receiving end. Using the variable j to traverse all subcarriers, it can be expressed as:

[0085]

[0086] The minimum value of the transmission rate of the first broadcast service signal is calculated based on the signal to interference and noise ratio of the first broadcast service signal.

[0087] The broadcast rate of the terminal users accessing BWP1 is expressed as the minimum value of the broadcast service receiving rate of all terminal users accessing BWP1:

[0088]

[0089] The second broadcast service signal received by the terminal user in the second carrier bandwidth is calculated based on the second carrier bandwidth occupied by the broadcast tower, the power allocated by the broadcast tower to the second carrier bandwidth, and the subcarrier spacing of the second carrier bandwidth occupied by the broadcast tower.

[0090] The speed of terminal user k satisfies v1<v k ≤v2, v2=250km / h, and the user is in Cor near Within the range, terminal user k accesses BWP2, and the subcarrier spacing is configured as At this time, the radio tower H The coverage range of terminal user k in subcarrier The receiving of the second broadcast service signal can be expressed as:

[0091]

[0092] The first term of the formula represents the end user k in the subcarrier Receive base station f H The broadcast signal sent on the carrier bandwidth part BWP2, the second term of the formula represents the adjacent base station in the subcarrier Since the signal sent on the network exceeds the multi-path delay range, it is considered interference, noise. Indicates that the noise has a mean of 0 and a variance of is a complex Gaussian random variable, and N0 represents the one-sided power spectral density of the noise.

[0093] A signal to interference and noise ratio of the second broadcast service signal is calculated based on the second broadcast service signal.

[0094] End user k in subcarrier The signal-to-interference-to-noise ratio at the receiver is expressed as:

[0095]

[0096] Among them, the first term of the denominator of the signal-to-interference-noise ratio at the receiving end is Indicates that the subcarrier from the adjacent cell The interference signal sent to the end user k is not within the multi-path delay range of the transmitted signal. At this time, the end user only receives the interference signal from the broadcast tower f. H signal, and all other base stations will The signal on is regarded as interference and can be expressed as:

[0097]

[0098] Item 2 It indicates the inter-subcarrier interference caused by the high-speed movement of the terminal, which is expressed as:

[0099]

[0100] The third term indicates the subcarrier The additive Gaussian white noise received by the receiving end satisfies Indicates that the noise satisfies the mean of 0 and the variance is is a complex Gaussian distributed random variable, and N0 represents the unilateral power spectral density of the noise.

[0101] The minimum value of the transmission rate of the second broadcast service signal is calculated based on the signal to interference and noise ratio of the second broadcast service signal.

[0102] End user k in subcarrier The rate of receiving broadcast services can be expressed as:

[0103]

[0104] It can be obtained that the rate at which user k receives broadcast services in the BWP2 band can be expressed as:

[0105]

[0106] The broadcast rate of users accessing BWP2 is expressed as the minimum value of the broadcast service rate received by all users accessing BWP2:

[0107]

[0108] A minimum value of the broadcast tower broadcast service signal transmission rate is calculated based on a minimum value of the first broadcast service signal transmission rate and a minimum value of the second broadcast service signal transmission rate.

[0109] It is necessary to optimize the broadcast service transmission of all users accessing the broadcast tower. It is necessary to optimize the bandwidth allocation factors α1, α2, and the power carried on each subcarrier in the carrier bandwidth parts BWP1, BWP2, so as to maximize the minimum value of the broadcast service transmission rate received by users accessing the broadcast tower.

[0110] The optimization problem can be written as:

[0111]

[0112] The variables in this optimization problem are the power allocated on the subcarriers and bandwidth allocation factors a1 and a2. Due to the existence of variables α1 and α2, the number of subcarriers in the frequency domain will change for different values ​​of the variables α1 and α2, and the dimension of the power allocation matrix will also change. The convex optimization solution cannot be used directly for the solution. This embodiment proposes an algorithm based on a joint solution of a genetic algorithm and convex optimization. A genetic algorithm is used to iteratively solve the variables α1 and α2, and the global optimal solution of α1 and α2 is iterated through genetic algorithm population selection, chromosome crossover, and chromosome mutation. In order to maximize the minimum receiving rate of terminal users accessing the broadcast service, the system frequency band should be utilized as much as possible. The constraint condition α1+α2≤1 can be written as α1+α2=1, then α2=1-α1.

[0113] In the iterative update of the genetic algorithm, the corresponding α1 and α2 of each generation of population are certain. On this basis, the optimization problem is transformed into a convex optimization problem and solved using the cvx toolbox. When the SNR at the transmitting end is determined, if the total power allocated to the carrier bandwidth part BWP1 becomes larger, the broadcast service rate of the carrier bandwidth part BWP1 will increase accordingly, and the total power of the carrier bandwidth part BWP2 The broadcast service rate of the carrier bandwidth part BWP2 will become smaller accordingly. However, the optimization problem is to maximize the minimum value of all broadcast service rates in the system. Therefore, it can be analyzed that when the minimum value of the broadcast rate of all terminal users accessing the carrier bandwidth part BWP1 is equal to the minimum value of the broadcast rate of all terminal users accessing the carrier bandwidth part BWP2, that is, When , the minimum broadcast service rate of all terminal users in the system can be maximized. The minimum infimum t of the system broadcast service rate is introduced into the optimization problem, so that The original optimization problem is transformed into:

[0114]

[0115] Since the fifth and sixth constraints cannot be solved in cvx, constants c1, c2, c3, c4 are introduced and defined as follows:

[0116]

[0117] Then the fifth and sixth constraints can be changed to:

[0118]

[0119]

[0120] Transforming the convex optimization problem into standard form, we can obtain:

[0121]

[0122] st-t≤0

[0123]

[0124]

[0125]

[0126]

[0127]

[0128] Enter the problem into the cvx toolbox for solution. In order to run the program smoothly in the simulation, Mosek9.1.9 of cvx 2.2 is used to solve the minimum transmission rate of the broadcast tower broadcast service signal.

[0129] The cellular base station broadcast service signal received by the terminal user is calculated based on the bandwidth occupied by the cellular base station in the broadcast service, the power of the cellular base station in the broadcast service, and the subcarrier spacing of the cellular base station in the broadcast service.

[0130] Assume the number of cellular base stations is F L , the set of cellular base stations is represented as The set of cellular base stations whose signals transmitted to the terminal user k are within the multipath delay range of the cellular base stations is expressed as Assume the number of terminal users is K, and the terminal user set is expressed as In Cor near The set of end users in a region is represented as In Cor edge The set of end users in a region is represented as Assume that the bandwidth of the cellular base station system is w L , the subcarrier spacing is configured as Δf L =15kHz, cyclic prefix is ​​cp L =16.67μs, the occupancy of the cellular system band by broadcast service, multicast service and unicast service is β1w respectively L ,β2w L ,β3w L , and β1+β2+β3≤1, the number of subcarriers occupied by the cellular base station is N L , the cellular base station subcarrier set is expressed as satisfy The number of subcarriers used to transmit broadcast services is The broadcast service subcarrier set is expressed as The number of subcarriers used to transmit multicast services is The multicast service subcarrier set is expressed as The number of subcarriers used to transmit unicast services is The unicast service subcarrier set is expressed as represents the cellular base station f L and the channel of end user k on subcarrier n, cellular base station f L The power of the transmitted broadcast is expressed as The power allocated to subcarrier n can be expressed as satisfy Similarly, the cellular base station f L The transmission power of multicast is expressed as The power allocated to subcarrier n can be expressed as satisfy Cellular base station L The power of transmitting unicast is expressed as The power allocated to subcarrier n can be expressed as satisfy Assume that the cellular base station f L The transmission power is satisfy

[0131] The broadcast, multicast, and unicast service information sent by the cellular base station transmitter can be expressed as:

[0132]

[0133]

[0134]

[0135] Among them, in Cor edge The cellular base stations in the area need to send broadcast, multicast and unicast service information. near Cellular base stations within the range need to send multicast and unicast service information, where Indicates the signal power carried by each subcarrier in the broadcast service part of the cellular network. Indicates the broadcast service information carried on each subcarrier in the cellular network transmission broadcast service part. Similarly, Indicates the signal power carried by each subcarrier in the multicast service transmission part of the cellular network. Indicates the multicast service information carried by each subcarrier in the multicast service part of the cellular network. Indicates the signal power carried by each subcarrier in the unicast service part of the cellular network. Indicates the unicast service information carried by each subcarrier in the cellular network transmission unicast service part.

[0136] End user k is in Cor edge Edge area, and the end user moving speed v k ≥67.5km / h, that is When the end user chooses to access Cor edge β1w in cellular base station L frequency band, at this time, the end user k is in the subcarrier The broadcast service signal received on is expressed as:

[0137]

[0138] The first term of the formula is the subcarrier received by the end user k. The second term is the signal sent by the base station within the multipath delay range on the subcarrier The base station signal that is not within the multipath delay range of the transmitted signal is treated as interference. The third term of the formula represents the terminal user's subcarrier The received Gaussian white noise has a distribution Indicates that the noise satisfies the mean of 0 and the variance is N0Δf L is a complex Gaussian distributed random variable, and N0 represents the one-sided power spectral density of the noise.

[0139] The signal to interference and noise ratio of the cellular base station broadcast service signal is calculated based on the cellular base station broadcast service signal.

[0140] End user k in subcarrier The signal to noise ratio on can be expressed as:

[0141]

[0142] The first term in the denominator Indicates the subcarrier from the adjacent cellular base station The interference on is expressed as:

[0143]

[0144] The second term in the denominator represents the inter-subcarrier interference caused by the high-speed movement of the terminal to the receiving end. Here, the impact of Doppler frequency shift on the receiving end is quantified, f d,max Indicates the maximum Doppler generated by the high-speed movement at the receiving end. All subcarriers are traversed using the variable j, expressed as:

[0145]

[0146] The minimum value of the cellular base station broadcast service transmission rate is calculated based on the signal to interference and noise ratio of the cellular base station broadcast service signal, and the minimum value of the cellular base station broadcast service transmission rate is greater than or equal to the minimum value of the broadcast tower broadcast service transmission rate.

[0147] End user k in subcarrier The rate of receiving broadcast services can be expressed as:

[0148]

[0149] Therefore, we can get the terminal user k in the cellular base station β1w L The rate at which broadcast services are received within the carrier bandwidth portion can be expressed as:

[0150]

[0151] The minimum broadcast service rate of a cellular base station can be expressed as:

[0152]

[0153] and

[0154]

[0155] The cellular base station multicast service signal received by the terminal user is calculated based on the bandwidth occupied by the cellular base station in the multicast service, the power of the cellular base station in the multicast service, and the subcarrier spacing of the cellular base station in the multicast service.

[0156] In the service transmission system, multicast is a two-way communication with feedback between the base station and the end user, which is carried by the cellular base station. The bandwidth for transmitting multicast services is β2w L , the number of subcarriers is The multicast service subcarrier set is expressed as The minimum granularity for carrying multicast services is one RE, and the maximum number of multicast services carried is For a comprehensive analysis, a multicast service is carried by only one RE. Each cellular base station transmits the same multicast service, which is carried on the subcarrier. Multicast services on express, represents base station f L The signal carried on subcarrier n in the multicast service sent, assuming that the multicast service The set of receiving terminal users is expressed as For end users In subcarrier The multicast service signal received on can be expressed as:

[0157]

[0158] The first term of the formula represents the signal received by the terminal user k from the base station within the multipath delay range and carried on the subcarrier The multicast signal on the receiver is received by diversity. The second item indicates that the base station received by the terminal user k is not within the multipath delay range of the transmitted signal and is carried on the subcarrier The receiver regards this part of the signal as interference. The third item indicates that the terminal user The noise received meets Indicates that the noise satisfies the mean of 0 and the variance is N0Δf L is a complex Gaussian distributed random variable, and N0 represents the unilateral power spectral density of the noise.

[0159] The signal to interference and noise ratio of the cellular base station multicast service signal is calculated based on the cellular base station multicast service signal.

[0160] End User Receive broadcast services on subcarriers Receiving multicast services The signal-to-interference-noise ratio can be expressed as:

[0161]

[0162] in Indicates the interference on the same subcarrier from adjacent base stations.

[0163]

[0164] Indicates the inter-carrier interference caused by the high-speed movement of the terminal.

[0165]

[0166] The minimum value of the multicast service transmission rate of the cellular base station is calculated based on the signal to interference and noise ratio of the multicast service signal of the cellular base station.

[0167] End User In subcarrier Receiving multicast services The rate can be expressed as:

[0168]

[0169] Cellular base station transmission of multicast services The rate at which multicast traffic is received End users The minimum value in can be expressed as:

[0170]

[0171] The rate at which the service transmission system transmits multicast services can be expressed as:

[0172]

[0173] For the transmission of multicast services, the minimum transmission rate of the system multicast services can be set according to the actual terminal user service requirements. That is, there are the following constraints:

[0174]

[0175] The maximum value of the cellular base station unicast service transmission rate is calculated based on the minimum value of the broadcast tower broadcast service transmission rate and the minimum value of the cellular base station multicast service transmission rate.

[0176] Unicast in the service transmission system is a two-way feedback communication between the base station and the end user, which is carried by the cellular base station. The bandwidth for carrying unicast services is β3w L , the number of subcarriers used to transmit unicast services is The subcarrier set is represented as Here, considering the ideal application situation, each subcarrier uses OFDMA to carry one terminal user data. Suppose subcarrier n carries unicast service information. The terminal user receiving the unicast service on subcarrier n is denoted as k n , at base station f L Coverage, end users The received unicast signal on the subcarrier can be expressed as:

[0177]

[0178] The first term of the formula represents the base station f LThe unicast information received by terminal user k in the coverage area on subcarrier n, the second term of the formula represents the neighboring base station f on subcarrier n L' Transmit to The third item indicates the unicast information of the terminal user on the subcarrier The noise received on the Indicates that the noise satisfies the mean of 0 and the variance is N0Δf L A complex Gaussian random variable, N0 represents the unilateral power spectral density of the noise. It acts as interference at the end user k. The received unicast signal to interference and noise ratio can be expressed as:

[0179]

[0180] in Indicates that the subcarrier from the adjacent cell Interference from adjacent cells.

[0181]

[0182] The second term in the denominator represents the self-carrier interference caused by the high-speed movement of the terminal. Here, the influence of Doppler frequency shift on the receiving end is quantified. d,max Indicates the maximum Doppler generated by the high-speed movement at the receiving end. All subcarriers are traversed using the variable j, expressed as:

[0183]

[0184] Then the transmission rate of terminal user k can be expressed as:

[0185]

[0186] The sum rate of the system transmitting unicast services can be obtained by summing the unicast receiving rates of all terminal users in the system. The sum rate of the system transmitting unicast services can be expressed as:

[0187]

[0188] The optimization goal of the model in the cellular network is to maximize the system unicast transmission rate while meeting the broadcast service transmission rate and multicast service transmission rate. The optimization problem is written as follows:

[0189]

[0190] The maximum transmission rate of the unicast service of the cellular base station can be obtained by combining them.

[0191] By adopting the technical solution of this embodiment, the broadcast tower is divided into two carrier bandwidth parts in the frequency domain, each of which is configured with a different broadcast transmission physical layer parameter set, and respectively carries the broadcast services of fixed and low-speed terminal users in the entire area, and the broadcast services of high-speed mobile terminal users close to the broadcast tower. The cellular base station is divided into three carrier bandwidth parts, which are responsible for carrying the broadcast services of high-speed mobile terminal users far away from the broadcast tower, the multicast services of all terminal users in the area, and the unicast services of all terminal users in the area. By reasonably allocating resources in the service transmission system for multi-service transmission, the bit error rate of system transmission is reduced. In addition, the power optimization algorithm is used to maximize the unicast service transmission rate while ensuring the transmission rate of the broadcast service and the multicast service, thereby ensuring the optimal allocation of system resources and enhancing the user experience of the terminal users.

[0192] The second aspect of the present invention provides a multi-service transmission method based on heterogeneous network deployment, including:

[0193] Setting a broadcast tower, the broadcast tower is used to undertake the broadcast services of terminal users whose moving speed is less than or equal to a preset speed within the coverage area, and the broadcast services of terminal users whose moving speed is greater than the preset speed within a preset range from the broadcast tower;

[0194] A plurality of cellular base stations are set up, and the plurality of cellular base stations are all located within the coverage area, and the plurality of cellular base stations are used to undertake broadcast services for other terminal users within the coverage area.

[0195] By adopting the technical solution of the present invention, a service transmission system consisting of a broadcast tower and a cellular base station is established, and service transmission is carried out through collaboration between the broadcast tower and the cellular base station, which not only meets the coverage of terrestrial broadcast services, but also improves the service transmission quality for high-speed mobile terminal users in the area, thereby improving the user experience of the terminal users.

[0196] For example, the corresponding access criteria are set. The broadcast tower is set to work at a carrier frequency of 600 MHZ, and the bandwidth occupied by the broadcast tower is divided into the first carrier bandwidth BWP1 H With the second carrier bandwidth BWP2 H . Set BWP1 H The subcarrier spacing is Cyclic prefix Setting up BWP2 H The subcarrier spacing is Cyclic prefix The preset speed is 67.5km / h and the preset range is 10km. When the terminal user is within the coverage of the broadcast tower, its position remains unchanged or its speed is less than or equal to 67.5km / h, the terminal user is connected to the BWP1. HThe carrier bandwidth is used for broadcast service transmission. When the end user is less than 10 km from the broadcast tower and the moving speed is greater than 67.5 km / h and less than 250 km / h, the end user is connected to BWP2. H The carrier bandwidth is used for broadcast service transmission. The cellular base station is set to operate at a carrier frequency of 700 MHZ, and the carrier bandwidth of the cellular base station broadcast service is set to The subcarrier spacing is Δf L =15kHz, cyclic prefix is ​​cp L =15kHz. When the distance between the terminal user and the broadcast tower is greater than 10km and the moving speed is greater than 67.5km / h and less than 250km / h, the terminal user is connected to the cellular base station for broadcast service transmission.

[0197] According to some embodiments of the present invention, the plurality of cellular base stations are further configured to undertake multicast services for all terminal users within the coverage area.

[0198] For example, the cellular base station is set to operate at a carrier frequency of 700 MHz, and the carrier bandwidth of the cellular base station multicast service is set to The subcarrier spacing is Δf L =15kHz, cyclic prefix is ​​cp L =15kHz. For multicast services of terminal users within the coverage area, the terminal users are connected to The carrier bandwidth is used for multicast service transmission.

[0199] According to some embodiments of the present invention, the multiple cellular base stations are also used to undertake unicast services for all terminal users within the coverage area.

[0200] For example, the cellular base station is set to operate at a carrier frequency of 700 MHz, and the carrier bandwidth of the unicast service of the cellular base station is set to The subcarrier spacing is Δf L =15kHz, cyclic prefix is ​​cp L =15kHz. For unicast services of terminal users within the coverage area, the terminal users are connected to The carrier bandwidth is used for unicast service transmission.

[0201] According to some embodiments of the present invention, the method further comprises: controlling the transmission rates of the broadcast service and the multicast service to be minimum so as to maximize the transmission rate of the unicast service.

[0202] For example, a control system is provided in the service transmission system based on heterogeneous network deployment to control the transmission rates of the broadcast service and the multicast service to be minimum so as to maximize the transmission rate of the unicast service.

[0203] Specifically, in some embodiments of the present invention, controlling the transmission rates of the broadcast service and the multicast service to be minimum so as to maximize the transmission rate of the unicast service includes:

[0204] Calculating a minimum transmission rate corresponding to a first carrier bandwidth of the broadcast tower, where the first carrier bandwidth is used to bear broadcast services of terminal users within the coverage area whose moving speed is less than or equal to a preset speed;

[0205] Calculating a minimum transmission rate corresponding to a second carrier bandwidth of the broadcast tower, where the second carrier bandwidth is used to bear broadcast services of terminal users within a preset range from the broadcast tower and whose moving speed is greater than a preset speed;

[0206] Calculating a minimum transmission rate of the broadcast tower broadcast service based on a minimum transmission rate corresponding to the first carrier bandwidth and a minimum transmission rate corresponding to the second carrier bandwidth;

[0207] respectively calculating a minimum transmission rate corresponding to a broadcast service and a minimum transmission rate corresponding to a multicast service of the cellular base station;

[0208] Based on the minimum transmission rate of the broadcast tower broadcast service, the minimum transmission rate corresponding to the cellular base station broadcast service, and the minimum transmission rate corresponding to the cellular base station multicast service, the maximum value of the cellular base station unicast service transmission rate is calculated.

[0209] According to some embodiments of the present invention, controlling the transmission rates of the broadcast service and the multicast service to be minimum so as to maximize the transmission rate of the unicast service includes:

[0210] The bandwidth occupied by the broadcast tower is divided into subcarriers with a spacing of The cyclic prefix is The first carrier bandwidth BWP1 H With subcarrier spacing of The cyclic prefix is The second carrier bandwidth BWP2 H .

[0211] The bandwidth occupied by the cellular base station is divided into subcarriers with a spacing of Δf. L = 15kHz third carrier bandwidth Fourth carrier bandwidth and the fifth carrier bandwidth

[0212] When terminal user k receives broadcast services, he needs to k and speed v kSelectively access broadcast service resources from broadcast towers and cellular base stations. If the terminal user's mobile speed v k ≤67.5km / h, then connect to the broadcast tower BWP1 H Carrier bandwidth part. If the terminal user's moving speed is 67.5km / h<v k ≤250km / h, and in area l k ∈Cor near ,Cor near If the distance to the broadcast tower is less than or equal to 10 km, then access the broadcast tower BWP2 H Carrier bandwidth part. If the terminal user's moving speed is 67.5km / h<v k ≤250km / h, and in area l k ∈Cor edge ,Cor edge If the distance from the broadcast tower is greater than 10 km, then access Cor edge BWP1 for the cellular network broadcasting service portion within the region L Carrier bandwidth. For receiving multicast services, the terminal user determines the location l k and moving speed v k , select the multicast service carrier bandwidth portion BWP2 corresponding to the adjacent cellular base station L , realizing multi-base station joint transmission. For receiving unicast services, the terminal user selects the carrier bandwidth part BWP3 of the nearest cellular base station to access. L , and remove interference from adjacent base stations on the same subcarrier.

[0213] The first broadcast service signal of the broadcast tower received by the terminal user in the first carrier bandwidth is calculated based on the first carrier bandwidth occupied by the broadcast tower, the power allocated by the broadcast tower to the first carrier bandwidth, and the subcarrier spacing of the first carrier bandwidth occupied by the broadcast tower.

[0214] In this embodiment, the number of broadcast towers is F H , the broadcast tower set is represented as The number of terminal users in the service transmission system is K, and the terminal user set is expressed as The set of broadcast towers whose signals transmitted to end user k are within the multipath delay range of the broadcast towers is expressed as The set of end users accessing the broadcast tower BWP1 is represented as The set of end users accessing the broadcast tower BWP2 is represented as In Cor near The set of end users in scope is represented as The broadcast tower uses a single antenna to transmit broadcast services. The end user receiving end is a single antenna. The transmission bandwidth of the broadcast tower is w HThe bandwidth occupied by the first carrier bandwidth BWP1 is represented by α1w H , the subcarrier spacing is The number of subcarriers in the BWP1 part is The BWP1 partial subcarrier set can be The bandwidth occupied by the second carrier bandwidth BWP2 is represented by α2w H , the subcarrier spacing is The number of subcarriers in the BWP2 part is The BWP2 partial subcarrier set can be Indicates the broadcast tower f H and the channel parameters of end user k on subcarrier n, Indicates broadcasting Tata f H The BWP1 part carries the broadcast service information on subcarrier n. Indicates the broadcast tower f H The broadcast service information carried on subcarrier n in the BWP2 part, Indicates the broadcast tower f H The power allocated to the broadcast service on the first carrier bandwidth BWP1, Indicates that The power allocated to subcarrier n satisfies Similarly, Indicates the broadcast tower f H The power allocated to the broadcast service on the second carrier bandwidth BWP2, Indicates that The power allocated to subcarrier n satisfies Broadcast Tower H The power allocated to BWP1 and the power allocated to BWP2 need to be no greater than the total transmission power of the broadcast tower, that is, The broadcast towers in the system use the same power allocation scheme on each subcarrier.

[0215] The channel between broadcast tower f and end user k on subcarrier n can be expressed as:

[0216]

[0217] in represents the channel between base station f and end user k on subcarrier n, Is a scalar, indicating the channel Path loss and shadow fading, where PL represents the path loss, and its value is based on the spatial field strength distribution given in ITU-RP.1546-6 [6], σ sh Indicates channel The standard deviation of the shadow fading, σ sh =5.5dB[7]. It represents small-scale fading and conforms to a complex Gaussian distribution with a mean of 0 and a variance of 1.

[0218] In the system, N0 represents the unilateral power spectrum density of white noise.

[0219] N0=k×T×NF(W / Hz)

[0220] where k = 1.381*10 -23 J / K represents the Boltzmann constant, T represents the absolute temperature of noise, and here we assume that the temperature is T = 290K (16.85°C), and NF represents the noise factor, and here we take NF = 6dB[7].

[0221] Broadcast Tower H At the transmitting end, the same broadcast service information is carried in the two carrier bandwidth parts BWP1 and BWP2 respectively. The transmitting end can be:

[0222]

[0223]

[0224] in The main diagonal is Dimension, represents the signal power carried by each subcarrier in the BWP1 part, Indicates the broadcast service information carried on each subcarrier of the BWP1 part of the broadcast tower. The main diagonal is Dimension, represents the signal power carried by each subcarrier in the BWP2 part, Indicates the broadcast service information carried on each subcarrier of the BWP2 part of the broadcast tower.

[0225] Within the coverage area of ​​the broadcast tower, if the terminal user k has a speed v k ≤v1, v1=67.5km. Then access BWP1, the subcarrier spacing is Because the transmission power of the broadcast tower is large, the terminal user can receive the signals transmitted by multiple broadcast towers and perform signal diversity reception. The terminal user k is in the subcarrier The first broadcast service signal received on the

[0226]

[0227] The first term in the formula represents the end user k in the subcarrier The second term is the signal sent by the end user k in the subcarrier Signals received on the network that are not within the multipath delay range of the base station's transmitted signal are considered interference. Indicates that the subcarrier The noise received on

[0228] A signal to interference and noise ratio of the first broadcast service signal is calculated based on the first broadcast service signal.

[0229] End user k in subcarrier The signal-to-interference-to-noise ratio of the broadcast service received on the CAN bus can be expressed as:

[0230]

[0231] The first term in the denominator Indicates that the subcarrier from the adjacent cell The signal sent to the terminal user k that is not within the multi-path delay range of the transmitted signal is regarded as interference and is expressed as:

[0232]

[0233] The second term in the denominator It represents the inter-carrier interference caused by the high-speed movement of the terminal to the receiving end. Here, the influence of Doppler frequency shift on the receiving end is quantified. d,max Indicates the maximum Doppler generated by the high-speed movement at the receiving end. All subcarriers are traversed using the variable j, expressed as:

[0234]

[0235] The minimum value of the transmission rate of the first broadcast service signal is calculated based on the signal to interference and noise ratio of the first broadcast service signal.

[0236] The broadcast rate of the terminal users accessing BWP1 is expressed as the minimum value of the broadcast service receiving rate of all terminal users accessing BWP1:

[0237]

[0238] The second broadcast service signal received by the terminal user in the second carrier bandwidth is calculated based on the second carrier bandwidth occupied by the broadcast tower, the power allocated by the broadcast tower to the second carrier bandwidth, and the subcarrier spacing of the second carrier bandwidth occupied by the broadcast tower.

[0239] The speed of terminal user k satisfies v1<v k ≤v2, v2=250km / h, and the end user is in Cor near Within the range, terminal user k accesses BWP2, and the subcarrier spacing is configured as At this time, the radio tower H The coverage range of terminal user k in subcarrier The receiving of the second broadcast service signal can be expressed as:

[0240]

[0241] The first term of the formula represents the end user k in the subcarrier Receive base station f H The broadcast signal sent on the carrier bandwidth part BWP2, the second term of the formula represents the adjacent base station in the subcarrier Since the signal sent on the network exceeds the multi-path delay range, it is considered interference, noise.

[0242] A signal to interference and noise ratio of the second broadcast service signal is calculated based on the second broadcast service signal.

[0243] End user k in subcarrier The signal-to-interference-to-noise ratio at the receiver is expressed as:

[0244]

[0245] Among them, the first term of the denominator of the signal-to-interference-noise ratio at the receiving end is Indicates that the subcarrier from the adjacent cell The interference signal sent to the end user k is not within the multi-path delay range of the transmitted signal. At this time, the end user only receives the interference signal from the broadcast tower f. H signal, and all other base stations will The signal on is regarded as interference and can be expressed as:

[0246]

[0247] Item 2 It indicates the inter-subcarrier interference caused by the high-speed movement of the terminal, which is expressed as:

[0248]

[0249] The third term indicates the subcarrier The additive Gaussian white noise received by the receiving end satisfies Indicates that the noise has a mean of 0 and a variance of is a complex Gaussian random variable, and N0 represents the one-sided power spectral density of the noise.

[0250] The minimum value of the transmission rate of the second broadcast service signal is calculated based on the signal to interference and noise ratio of the second broadcast service signal.

[0251] End user k in subcarrier The rate of receiving broadcast services can be expressed as:

[0252]

[0253] It can be obtained that the rate at which terminal user k receives broadcast services in the BWP2 band can be expressed as:

[0254]

[0255] The broadcast rate of the terminal users accessing BWP2 is expressed as the minimum value of the broadcast service receiving rate of all terminal users accessing BWP2:

[0256]

[0257] A minimum value of the broadcast tower broadcast service signal transmission rate is calculated based on a minimum value of the first broadcast service signal transmission rate and a minimum value of the second broadcast service signal transmission rate.

[0258] It is necessary to optimize the broadcast service transmission for all terminal users accessing the broadcast tower. It is necessary to optimize the bandwidth allocation factors α1, α2, and the power carried on each subcarrier in the carrier bandwidth parts BWP1, BWP2, so as to maximize the minimum value of the broadcast service transmission rate received by the terminal users accessing the broadcast tower.

[0259] The optimization problem can be written as:

[0260]

[0261] The variables in this optimization problem are the power allocated on the subcarriers and bandwidth allocation factors a1 and a2. Due to the existence of variables α1 and α2, the number of subcarriers in the frequency domain will change for different values ​​of the variables α1 and α2, and the dimension of the power allocation matrix will also change. The convex optimization solution cannot be used directly for the solution. This embodiment proposes an algorithm based on a joint solution of a genetic algorithm and convex optimization. A genetic algorithm is used to iteratively solve the variables α1 and α2, and the global optimal solution of α1 and α2 is iterated through genetic algorithm population selection, chromosome crossover, and chromosome mutation. In order to maximize the minimum receiving rate of terminal users accessing the broadcast service, the system frequency band should be utilized as much as possible. The constraint condition α1+α2≤1 can be written as α1+α2=1, then α2=1-α1.

[0262] In the iterative update of the genetic algorithm, the corresponding α1 and α2 of each generation of population are certain. On this basis, the optimization problem is transformed into a convex optimization problem and solved using the cvx toolbox. When the SNR at the transmitting end is determined, if the total power allocated to the carrier bandwidth part BWP1 becomes larger, the broadcast service rate of the carrier bandwidth part BWP1 will increase accordingly, and the total power of the carrier bandwidth part BWP2 The broadcast service rate of the carrier bandwidth part BWP2 will become smaller accordingly. However, the optimization problem is to maximize the minimum value of all broadcast service rates in the system. Therefore, it can be analyzed that when the minimum value of the broadcast rate of all terminal users accessing the carrier bandwidth part BWP1 is equal to the minimum value of the broadcast rate of all terminal users accessing the carrier bandwidth part BWP2, that is, When , the minimum broadcast service rate of all terminal users in the system can be maximized. The minimum infimum t of the system broadcast service rate is introduced into the optimization problem, so that The original optimization problem is transformed into:

[0263]

[0264] Since the fifth and sixth constraints cannot be solved in cvx, constants c1, c2, c3, c4 are introduced and defined as follows:

[0265]

[0266] Then the fifth and sixth constraints can be changed to:

[0267]

[0268]

[0269] Transforming the convex optimization problem into standard form, we can obtain:

[0270]

[0271] st-t≤0

[0272]

[0273]

[0274]

[0275]

[0276]

[0277] Enter the problem into the cvx toolbox for solution. In order to run the program smoothly in the simulation, Mosek9.1.9 of cvx 2.2 is used to solve the minimum transmission rate of the broadcast tower broadcast service signal.

[0278] The cellular base station broadcast service signal received by the terminal user is calculated based on the bandwidth occupied by the cellular base station in the broadcast service, the power of the cellular base station in the broadcast service, and the subcarrier spacing of the cellular base station in the broadcast service.

[0279] Assume the number of cellular base stations is F L , the set of cellular base stations is represented as The set of cellular base stations whose signals transmitted to the terminal user k are within the multipath delay range of the cellular base stations is expressed as Assume that the number of terminal users is K, and the terminal user set is represented by K = {1, 2, ... k, ... K}, in Cor near The set of end users in a region is represented as In Cor edge The set of end users in a region is represented as Assume that the bandwidth of the cellular base station system is w L , the subcarrier spacing is configured as Δf L =15kHz, cyclic prefix is ​​cp L =16.67μs, the occupancy of the cellular system band by broadcast service, multicast service and unicast service is β1w respectively L ,β2w L ,β3w L , and β1+β2+β3≤1, the number of subcarriers occupied by the cellular base station is N L , the cellular base station subcarrier set is expressed as satisfy The number of subcarriers used to transmit broadcast services is The broadcast service subcarrier set is expressed as The number of subcarriers used to transmit multicast services is The multicast service subcarrier set is expressed as The number of subcarriers used to transmit unicast services is The unicast service subcarrier set is expressed as represents the cellular base station f L and the channel of end user k on subcarrier n, cellular base station f L The power of the transmitted broadcast is expressed as The power allocated to subcarrier n can be expressed as satisfy Similarly, the cellular base station f L The transmission power of multicast is expressed as The power allocated to subcarrier n can be expressed as satisfy Cellular base station L The power of transmitting unicast is expressed as The power allocated to subcarrier n can be expressed as satisfy Assume that the cellular base station f L The transmission power is satisfy

[0280] The broadcast, multicast, and unicast service information sent by the cellular base station transmitter can be expressed as:

[0281]

[0282]

[0283]

[0284] Among them, in Cor edge The cellular base stations in the area need to send broadcast, multicast and unicast service information. near Cellular base stations within the range need to send multicast and unicast service information, among which Indicates the signal power carried by each subcarrier in the broadcast service part of the cellular network. Indicates the broadcast service information carried on each subcarrier in the cellular network transmission broadcast service part. Similarly, Indicates the signal power carried by each subcarrier in the multicast service transmission part of the cellular network. Indicates the multicast service information carried by each subcarrier in the multicast service part of the cellular network. Indicates the signal power carried by each subcarrier in the unicast service part of the cellular network. Indicates the unicast service information carried by each subcarrier in the cellular network transmission unicast service part.

[0285] End user k is in Cor edge Edge area, and the end user moving speed v k ≥67.5km / h, that is When the end user chooses to access Cor edge β1w in cellular base station L frequency band, at this time, the end user k is in the subcarrier The broadcast service signal received on is expressed as:

[0286]

[0287] The first term of the formula is the subcarrier received by the end user k. The second term is the signal sent by the base station within the multipath delay range on the subcarrier The base station signal that is not within the multipath delay range of the transmitted signal is treated as interference. The third term of the formula indicates that the terminal user is on the subcarrier The received Gaussian white noise has a distribution Indicates that the noise satisfies the mean of 0 and the variance is N0Δf L is a complex Gaussian distributed random variable, and N0 represents the unilateral power spectral density of the noise.

[0288] The signal to interference and noise ratio of the cellular base station broadcast service signal is calculated based on the cellular base station broadcast service signal.

[0289] End user k in subcarrier The signal to noise ratio on can be expressed as:

[0290]

[0291] The first term in the denominator Indicates the subcarrier from the adjacent cellular base station The interference on is expressed as:

[0292]

[0293] The second term in the denominator represents the inter-subcarrier interference caused by the high-speed movement of the terminal to the receiving end. Here, the impact of Doppler frequency shift on the receiving end is quantified, f d,max Indicates the maximum Doppler generated by the high-speed movement at the receiving end. All subcarriers are traversed using the variable j, expressed as:

[0294]

[0295] The minimum value of the cellular base station broadcast service transmission rate is calculated based on the signal to interference and noise ratio of the cellular base station broadcast service signal, and the minimum value of the cellular base station broadcast service transmission rate is greater than or equal to the minimum value of the broadcast tower broadcast service transmission rate.

[0296] End user k in subcarrier The rate of receiving broadcast services can be expressed as:

[0297]

[0298] Therefore, we can get the terminal user k in the cellular base station β1w L The rate at which broadcast services are received within the carrier bandwidth portion can be expressed as:

[0299]

[0300] The minimum broadcast service rate of a cellular base station can be expressed as:

[0301]

[0302] and

[0303]

[0304] The cellular base station multicast service signal received by the terminal user is calculated based on the bandwidth occupied by the cellular base station in the multicast service, the power of the cellular base station in the multicast service, and the subcarrier spacing of the cellular base station in the multicast service.

[0305] In the service transmission system, multicast is a two-way communication with feedback between the base station and the end user, which is carried by the cellular base station. The bandwidth for transmitting multicast services is β2w L , the number of subcarriers is The multicast service subcarrier set is expressed as The minimum granularity for carrying multicast services is one RE, and the maximum number of multicast services carried is For a comprehensive analysis, a multicast service is carried by only one RE. Each cellular base station transmits the same multicast service, which is carried on the subcarrier. Multicast services on express, represents base station f L The signal carried on subcarrier n in the multicast service sent, assuming that the multicast service The set of receiving terminal users is expressed as For end users In subcarrier The multicast service signal received on can be expressed as:

[0306]

[0307] The first term of the formula represents the signal received by the terminal user k from the base station within the multipath delay range and carried on the subcarrier The multicast signal on the receiver is received by diversity. The second item indicates that the base station received by the terminal user k is not within the multipath delay range of the transmitted signal and is carried on the subcarrier The receiver regards this part of the signal as interference. The third item indicates that the terminal user The noise received meets Indicates that the noise satisfies the mean of 0 and the variance is N0Δf L is a complex Gaussian distributed random variable, and N0 represents the unilateral power spectral density of the noise.

[0308] The signal to interference and noise ratio of the cellular base station multicast service signal is calculated based on the cellular base station multicast service signal.

[0309] End User Receive broadcast services on subcarriers Receiving multicast services The signal-to-interference-noise ratio can be expressed as:

[0310]

[0311] in Indicates the interference on the same subcarrier from adjacent base stations.

[0312]

[0313] Indicates the inter-carrier interference caused by the high-speed movement of the terminal.

[0314]

[0315] The minimum value of the multicast service transmission rate of the cellular base station is calculated based on the signal to interference and noise ratio of the multicast service signal of the cellular base station.

[0316] End User In subcarrier Receiving multicast services The rate can be expressed as:

[0317]

[0318] Cellular base station transmission of multicast services The rate at which multicast traffic is received End users The minimum value in can be expressed as:

[0319]

[0320] The rate at which the service transmission system transmits multicast services can be expressed as:

[0321]

[0322] For the transmission of multicast services, the minimum transmission rate of the system multicast services can be set according to the actual terminal user service requirements. That is, there are the following constraints:

[0323]

[0324] The maximum value of the cellular base station unicast service transmission rate is calculated based on the minimum value of the broadcast tower broadcast service transmission rate and the minimum value of the cellular base station multicast service transmission rate.

[0325] Unicast in the service transmission system is a two-way feedback communication between the base station and the end user, which is carried by the cellular base station. The bandwidth for carrying unicast services is β3w L , the number of subcarriers used to transmit unicast services is The subcarrier set is represented as Here, considering the ideal application situation, each subcarrier uses OFDMA to carry one terminal user data. Suppose subcarrier n carries unicast service information. The terminal user receiving the unicast service on subcarrier n is denoted as k n , at base station f L Coverage, end users The received unicast signal on the subcarrier can be expressed as:

[0326]

[0327] The first term of the formula represents the base station f L The unicast information received by terminal user k in the coverage area on subcarrier n, the second term of the formula represents the neighboring base station f on subcarrier n L' Transmit to The third item indicates the unicast information of the terminal user on the subcarrier The noise received on the Indicates that the noise satisfies the mean of 0 and the variance is N0Δf L A complex Gaussian random variable, N0 represents the unilateral power spectral density of the noise. It acts as interference at the end user k. The received unicast signal to interference and noise ratio can be expressed as:

[0328]

[0329] in Indicates that the subcarrier from the adjacent cell Interference from adjacent cells.

[0330]

[0331] The second term in the denominator represents the self-carrier interference caused by the high-speed movement of the terminal. Here, the influence of Doppler frequency shift on the receiving end is quantified. d,max Indicates the maximum Doppler generated by the high-speed movement at the receiving end. All subcarriers are traversed using the variable j, expressed as:

[0332]

[0333] Then the transmission rate of terminal user k can be expressed as:

[0334]

[0335] The sum rate of the system transmitting unicast services can be obtained by summing the unicast receiving rates of all terminal users in the system. The sum rate of the system transmitting unicast services can be expressed as:

[0336]

[0337] The optimization goal of the model in the cellular network is to maximize the system unicast transmission rate while meeting the broadcast service transmission rate and multicast service transmission rate. The optimization problem is written as follows:

[0338]

[0339] The maximum transmission rate of the unicast service of the cellular base station can be obtained by combining them.

[0340] By adopting the technical solution of this embodiment, the broadcast tower is divided into two carrier bandwidth parts in the frequency domain, each of which is configured with a different broadcast transmission physical layer parameter set, and carries the broadcast services of fixed and low-speed terminal users in the entire area, and the broadcast services of high-speed mobile terminal users close to the broadcast tower. The cellular base station is divided into three carrier bandwidth parts, which are responsible for carrying the broadcast services of high-speed mobile terminal users far away from the broadcast tower, the multicast services of all terminal users in the area, and the unicast services of all terminal users in the area, respectively, reducing the bit error rate of system transmission. In addition, the power optimization algorithm is used to maximize the unicast service transmission rate while ensuring the transmission rate of the broadcast service and the multicast service, ensuring the reasonable allocation of system resources and enhancing the user experience of the terminal users.

[0341] The following is a detailed description of a multi-service transmission system based on heterogeneous network deployment constructed by a multi-service transmission method based on heterogeneous network deployment using a specific embodiment. It is worth noting that the following description is only an exemplary description and is not a specific limitation of the present invention. All similar structures and similar variations of the present invention should be included in the protection scope of the present invention.

[0342] In this embodiment, a square city with a side length of 128 km is taken as an example. Figure 2 ,The multi-service transmission system based on heterogeneous network deployment includes: a broadcast tower and a plurality of cellular base stations and a control system located within the coverage range of the broadcast tower. ,The plurality of cellular base stations are arranged around the broadcast tower.

[0343] Set the broadcast tower to work at a carrier frequency of 600 MHZ, and divide the bandwidth occupied by the broadcast tower into the first carrier bandwidth BWP1 H With the second carrier bandwidth BWP2 H . Set BWP1 H The subcarrier spacing is Cyclic prefix Setting up BWP2 H The subcarrier spacing is Cyclic prefix The preset speed is 67.5km / h and the preset range is 10km.

[0344] When the terminal user is within the coverage of the broadcast tower, its position remains unchanged or its speed is less than or equal to 67.5km / h, the terminal user is connected to the BWP1. H The carrier bandwidth is used for broadcast service transmission. When the end user is less than 10 km from the broadcast tower and the moving speed is greater than 67.5 km / h and less than 250 km / h, the end user is connected to BWP2. H The carrier bandwidth is used for broadcast service transmission.

[0345] The cellular base station is set to work at a carrier frequency of 700 MHz, and the bandwidth occupied by the cellular base station is divided into subcarriers with a spacing of Δf. L = 15kHz third carrier bandwidth Fourth carrier bandwidth and the fifth carrier bandwidth

[0346] When the distance between the terminal user and the broadcast tower is greater than 10 km and the moving speed is greater than 67.5 km / h and less than 250 km / h, the terminal user is connected to the cellular base station for broadcast service transmission. For multicast services of terminal users within the coverage area, the terminal user is connected to the cellular base station. The carrier bandwidth is used for multicast service transmission. For unicast services of terminal users within the coverage area, the terminal user is connected to The carrier bandwidth is used for unicast service transmission.

[0347] The control system will coordinate the signal transmission power allocation of broadcast towers and cellular base stations in the service transmission system for broadcast, multicast, and unicast services, and maximize the transmission rate of unicast services.

[0348] When receiving broadcast services, terminal user k needs to k and speed v k Selectively access broadcast service resources from broadcast towers and cellular base stations. If the terminal user's mobile speed v k ≤67.5km / h, then connect to the broadcast tower BWP1 H Carrier bandwidth part. If the terminal user's moving speed is 67.5km / h<v k ≤250km / h, and in area l k ∈Cor near ,Cor near If the distance to the broadcast tower is less than or equal to 10 km, then access the broadcast tower BWP2 H Carrier bandwidth part. If the terminal user's moving speed is 67.5km / h<v k ≤250km / h, and in area l k ∈Cor edge ,Coredge If the distance from the broadcast tower is greater than 10 km, then access Cor edge BWP1 for the cellular network broadcasting service portion within the region L Carrier bandwidth. For receiving multicast services, the terminal user determines the location l k and moving speed v k , select the multicast service carrier bandwidth portion BWP2 corresponding to the adjacent cellular base station L , realizing multi-base station joint transmission. For receiving unicast services, the terminal user selects the carrier bandwidth part BWP3 of the nearest cellular base station to access. L , and remove interference from adjacent base stations on the same subcarrier.

[0349] The first broadcast service signal of the broadcast tower received by the terminal user in the first carrier bandwidth is calculated based on the first carrier bandwidth occupied by the broadcast tower, the power allocated by the broadcast tower to the first carrier bandwidth, and the subcarrier spacing of the first carrier bandwidth occupied by the broadcast tower.

[0350] In this embodiment, the number of broadcast towers is F H , the broadcast tower set is represented as The number of terminal users in the service transmission system is K, and the terminal user set is expressed as The set of broadcast towers whose signals transmitted to end user k are within the multipath delay range of the broadcast towers is expressed as The set of end users accessing the broadcast tower BWP1 is represented as The set of end users accessing the broadcast tower BWP2 is represented as In Cor near The set of end users in scope is represented as The broadcast tower uses a single antenna to transmit broadcast services. The end user receiving end is a single antenna. The transmission bandwidth of the broadcast tower is w H The bandwidth occupied by the first carrier bandwidth BWP1 is represented by α1w H , the subcarrier spacing is The number of subcarriers in the BWP1 part is The BWP1 partial subcarrier set can be The bandwidth occupied by the second carrier bandwidth BWP2 is represented by α2w H , the subcarrier spacing is The number of subcarriers in the BWP2 part is The BWP2 partial subcarrier set can be Indicates the broadcast tower f H and the channel parameters of end user k on subcarrier n, Indicates broadcasting Tata f H The BWP1 part carries the broadcast service information on subcarrier n. Indicates the broadcast tower f H The broadcast service information carried on subcarrier n in the BWP2 part, Indicates the broadcast tower f H The power allocated to the broadcast service on the first carrier bandwidth BWP1, Indicates that The power allocated to subcarrier n satisfies Similarly, Indicates the broadcast tower f H The power allocated to the broadcast service on the second carrier bandwidth BWP2, Indicates that The power allocated to subcarrier n satisfies Broadcast Tower H The power allocated to BWP1 and the power allocated to BWP2 need to be no greater than the total transmission power of the broadcast tower, that is, The broadcast towers in the system use the same power allocation scheme on each subcarrier.

[0351] The channel between broadcast tower f and end user k on subcarrier n can be expressed as:

[0352]

[0353] in represents the channel between base station f and end user k on subcarrier n, Is a scalar, indicating the channel Path loss and shadow fading, where PL represents the path loss, and its value is based on the spatial field strength distribution given in ITU-RP.1546-6 [6], σ sh Indicates channel The standard deviation of the shadow fading, σ sh =5.5dB[7]. It represents small-scale fading and conforms to a complex Gaussian distribution with a mean of 0 and a variance of 1.

[0354] In the system, N0 represents the unilateral power spectrum density of white noise.

[0355] N0=k×T×NF(W / Hz)

[0356] where k = 1.381*10 -23 J / K represents the Boltzmann constant, T represents the absolute temperature of noise, and here we assume that the temperature is T = 290K (16.85°C), and NF represents the noise factor, and here we take NF = 6dB[7].

[0357] Broadcast Tower H At the transmitting end, the same broadcast service information is carried in the two carrier bandwidth parts BWP1 and BWP2 respectively. The transmitting end can be:

[0358]

[0359] in The main diagonal is Dimension, represents the signal power carried by each subcarrier in the BWP1 part, Indicates the broadcast service information carried on each subcarrier of the BWP1 part of the broadcast tower. The main diagonal is Dimension, represents the signal power carried by each subcarrier in the BWP2 part, Indicates the broadcast service information carried on each subcarrier of the BWP2 part of the broadcast tower.

[0360] Within the coverage area of ​​the broadcast tower, if the terminal user k has a speed v k ≤v1, v1=67.5km. Then access BWP1, the subcarrier spacing is Because the transmission power of the broadcast tower is large, the terminal user can receive the signals transmitted by multiple broadcast towers and perform signal diversity reception. The terminal user k is in the subcarrier The first broadcast service signal received on the

[0361]

[0362] The first term in the formula represents the end user k in the subcarrier The second term is the signal sent by the end user k in the subcarrier Signals received on the network that are not within the multipath delay range of the base station's transmitted signal are considered interference. Indicates that the subcarrier The noise received on

[0363] A signal to interference and noise ratio of the first broadcast service signal is calculated based on the first broadcast service signal.

[0364] End user k in subcarrier The signal-to-interference-noise ratio of the first broadcast service signal received on the UE can be expressed as:

[0365]

[0366] The first term in the denominator Indicates that the subcarrier from the adjacent cell The signal sent to the terminal user k that is not within the multi-path delay range of the transmitted signal is regarded as interference and is expressed as:

[0367]

[0368] The second term in the denominator It represents the inter-carrier interference caused by the high-speed movement of the terminal to the receiving end. Here, the influence of Doppler frequency shift on the receiving end is quantified. d,max Indicates the maximum Doppler generated by the high-speed movement at the receiving end. All subcarriers are traversed using the variable j, expressed as:

[0369]

[0370] The minimum value of the transmission rate of the first broadcast service signal is calculated based on the signal to interference and noise ratio of the first broadcast service signal.

[0371] The broadcast rate of the terminal users accessing BWP1 is expressed as the minimum value of the transmission rate of the first broadcast service signal received by all terminal users accessing BWP1:

[0372]

[0373] The second broadcast service signal received by the terminal user in the second carrier bandwidth is calculated based on the second carrier bandwidth occupied by the broadcast tower, the power allocated by the broadcast tower to the second carrier bandwidth, and the subcarrier spacing of the second carrier bandwidth occupied by the broadcast tower.

[0374] The speed of terminal user k satisfies v1<v k ≤v2, v2=250km / h, and the end user is in Cor near Within the range, terminal user k accesses BWP2, and the subcarrier spacing is configured as At this time, the radio tower H The coverage range of terminal user k in subcarrier The receiving of the second broadcast service signal can be expressed as:

[0375]

[0376] The first term of the formula represents the end user k in the subcarrier Receive base station f H The broadcast signal sent on the carrier bandwidth part BWP2, the second term of the formula represents the adjacent base station in the subcarrier Since the signal sent on the network exceeds the multi-path delay range, it is considered interference, noise.

[0377] A signal to interference and noise ratio of the second broadcast service signal is calculated based on the second broadcast service signal.

[0378] End user k in subcarrier The signal to interference and noise ratio of the second broadcast service signal on is expressed as:

[0379]

[0380] Among them, the first term of the denominator of the signal-to-interference-noise ratio at the receiving end is Indicates that the subcarrier from the adjacent cell The interference signal sent to the end user k is not within the multi-path delay range of the transmitted signal. At this time, the end user only receives the interference signal from the broadcast tower f. H signal, and all other base stations will The signal on is regarded as interference and can be expressed as:

[0381]

[0382] Item 2 It indicates the inter-subcarrier interference caused by the high-speed movement of the terminal, which is expressed as:

[0383]

[0384] The third term indicates the subcarrier The additive Gaussian white noise received by the receiving end satisfies Indicates that the noise has a mean of 0 and a variance of is a complex Gaussian random variable, and N0 represents the one-sided power spectral density of the noise.

[0385] The minimum value of the transmission rate of the second broadcast service signal is calculated based on the signal to interference and noise ratio of the second broadcast service signal.

[0386] End user k in subcarrier The rate at which the second broadcast service signal is received can be expressed as:

[0387]

[0388] It can be obtained that the rate at which terminal user k receives broadcast services in the BWP2 band can be expressed as:

[0389]

[0390] The broadcast rate of the terminal users accessing BWP2 is expressed as the minimum value of the second broadcast service signal transmission rate received by all terminal users accessing BWP2:

[0391]

[0392] A minimum value of the broadcast tower broadcast service signal transmission rate is calculated based on a minimum value of the first broadcast service signal transmission rate and a minimum value of the second broadcast service signal transmission rate.

[0393] It is necessary to optimize the broadcast service transmission for all terminal users accessing the broadcast tower. It is necessary to optimize the bandwidth allocation factors α1, α2, and the power carried on each subcarrier in the carrier bandwidth parts BWP1, BWP2, so as to maximize the minimum value of the broadcast service transmission rate received by the terminal users accessing the broadcast tower.

[0394] The optimization problem can be written as:

[0395]

[0396] The variables in this optimization problem are the power allocated on the subcarriers and bandwidth allocation factors a1 and a2. Due to the existence of variables α1 and α2, the number of subcarriers in the frequency domain will change for different values ​​of the variables α1 and α2, and the dimension of the power allocation matrix will also change. The convex optimization solution cannot be used directly for the solution. This embodiment proposes an algorithm based on a joint solution of a genetic algorithm and convex optimization. A genetic algorithm is used to iteratively solve the variables α1 and α2, and the global optimal solution of α1 and α2 is iterated through genetic algorithm population selection, chromosome crossover, and chromosome mutation. In order to maximize the minimum receiving rate of terminal users accessing the broadcast service, the system frequency band should be utilized as much as possible. The constraint condition α1+α2≤1 can be written as α1+α2=1, then α2=1-α1.

[0397] In the iterative update of the genetic algorithm, the corresponding α1 and α2 of each generation of population are certain. On this basis, the optimization problem is transformed into a convex optimization problem and solved using the cvx toolbox. When the SNR at the transmitting end is determined, if the total power allocated to the carrier bandwidth part BWP1 becomes larger, the broadcast service rate of the carrier bandwidth part BWP1 will increase accordingly, and the total power of the carrier bandwidth part BWP2 The broadcast service rate of the carrier bandwidth part BWP2 will become smaller accordingly. However, the optimization problem is to maximize the minimum value of all broadcast service rates in the system. Therefore, it can be analyzed that when the minimum value of the broadcast rate of all terminal users accessing the carrier bandwidth part BWP1 is equal to the minimum value of the broadcast rate of all terminal users accessing the carrier bandwidth part BWP2, that is, When , the minimum broadcast service rate of all terminal users in the system can be maximized. The minimum infimum t of the system broadcast service rate is introduced into the optimization problem, so that The original optimization problem is transformed into:

[0398]

[0399] Since the fifth and sixth constraints cannot be solved in cvx, constants c1, c2, c3, c4 are introduced and defined as follows:

[0400]

[0401] Then the fifth and sixth constraints can be changed to:

[0402]

[0403]

[0404] Transforming the convex optimization problem into standard form, we can obtain:

[0405] st-t≤0

[0406]

[0407]

[0408]

[0409]

[0410]

[0411] Enter the problem into the cvx toolbox for solution. In order to run the program smoothly in the simulation, Mosek9.1.9 of cvx 2.2 is used to solve the minimum transmission rate of the broadcast tower broadcast service signal.

[0412] The cellular base station broadcast service signal received by the terminal user is calculated based on the bandwidth occupied by the cellular base station in the broadcast service, the power of the cellular base station in the broadcast service, and the subcarrier spacing of the cellular base station in the broadcast service.

[0413] Assume the number of cellular base stations is F L , the cellular base station set is represented as The set of cellular base stations whose signals transmitted to the terminal user k are within the multipath delay range of the cellular base stations is expressed as Assume the number of terminal users is K, and the terminal user set is expressed as In Cor near The set of end users in a region is represented as In Cor edge The set of end users in a region is represented as Assume that the bandwidth of the cellular base station system is w L , the subcarrier spacing is configured as Δf L =15kHz, cyclic prefix is ​​cp L=16.67μs, the occupancy of the cellular system band by broadcast service, multicast service and unicast service is β1w respectively L ,β2w L ,β3w L , and β1+β2+β3≤1, the number of subcarriers occupied by the cellular base station is N L , the cellular base station subcarrier set is expressed as satisfy The number of subcarriers used to transmit broadcast services is The broadcast service subcarrier set is expressed as The number of subcarriers used to transmit multicast services is The multicast service subcarrier set is expressed as The number of subcarriers used to transmit unicast services is The unicast service subcarrier set is expressed as represents the cellular base station f L and the channel of end user k on subcarrier n, cellular base station f L The power of the transmitted broadcast is expressed as The power allocated to subcarrier n can be expressed as satisfy Similarly, the cellular base station f L The transmission power of multicast is expressed as The power allocated to subcarrier n can be expressed as satisfy Cellular base station L The power of transmitting unicast is expressed as The power allocated to subcarrier n can be expressed as satisfy Assume that the cellular base station f L The transmission power is satisfy

[0414] The broadcast, multicast, and unicast service information sent by the cellular base station transmitter can be expressed as:

[0415]

[0416]

[0417]

[0418] Among them, in Cor edge The cellular base stations in the area need to send broadcast, multicast and unicast service information. nearCellular base stations within the range need to send multicast and unicast service information, among which Indicates the signal power carried by each subcarrier in the broadcast service part of the cellular network. Indicates the broadcast service information carried on each subcarrier in the cellular network transmission broadcast service part. Similarly, Indicates the signal power carried by each subcarrier in the multicast service transmission part of the cellular network. Indicates the multicast service information carried by each subcarrier in the multicast service part of the cellular network. Indicates the signal power carried by each subcarrier in the unicast service part of the cellular network. Indicates the unicast service information carried by each subcarrier in the cellular network transmission unicast service part.

[0419] End user k is in Cor edge Edge area, and the end user moving speed v k ≥67.5km / h, that is When the end user chooses to access Cor edge β1w in cellular base station L frequency band, at this time, the end user k is in the subcarrier The cellular base station broadcast service signal received on is expressed as:

[0420]

[0421] The first term of the formula is the subcarrier received by the end user k. The second term is the signal sent by the base station within the multipath delay range on the subcarrier The base station signal that is not within the multipath delay range of the transmitted signal is treated as interference. The third term of the formula indicates that the terminal user is on the subcarrier The received Gaussian white noise has a distribution Indicates that the noise satisfies the mean of 0 and the variance is N0Δf L is a complex Gaussian distributed random variable, and N0 represents the unilateral power spectral density of the noise.

[0422] The signal to interference and noise ratio of the cellular base station broadcast service signal is calculated based on the cellular base station broadcast service signal.

[0423] End user k in subcarrier The signal-to-interference-to-noise ratio of the cellular base station broadcast service signal on can be expressed as:

[0424]

[0425] The first term in the denominator Indicates the subcarrier from the adjacent cellular base station The interference on is expressed as:

[0426]

[0427] The second term in the denominator represents the inter-subcarrier interference caused by the high-speed movement of the terminal to the receiving end. Here, the impact of Doppler frequency shift on the receiving end is quantified, f d,max Indicates the maximum Doppler generated by the high-speed movement at the receiving end. All subcarriers are traversed using the variable j, expressed as:

[0428]

[0429] The minimum value of the cellular base station broadcast service transmission rate is calculated based on the signal to interference and noise ratio of the cellular base station broadcast service signal, and the minimum value of the cellular base station broadcast service transmission rate is greater than or equal to the minimum value of the broadcast tower broadcast service transmission rate.

[0430] End user k in subcarrier The transmission rate of the received cellular base station broadcast service can be expressed as:

[0431]

[0432] Therefore, we can get the terminal user k in the cellular base station β1w L The transmission rate of the received cellular base station broadcast service within the carrier bandwidth portion can be expressed as:

[0433]

[0434] The minimum transmission rate of cellular base station broadcast services can be expressed as:

[0435]

[0436] and

[0437]

[0438] The cellular base station multicast service signal received by the terminal user is calculated based on the bandwidth occupied by the cellular base station in the multicast service, the power of the cellular base station in the multicast service, and the subcarrier spacing of the cellular base station in the multicast service.

[0439] In the service transmission system, multicast is a two-way communication with feedback between the base station and the end user, which is carried by the cellular base station. The bandwidth for transmitting multicast services is β2w L , the number of subcarriers is The multicast service subcarrier set is expressed as The minimum granularity for carrying multicast services is one RE, and the maximum number of multicast services carried is For a comprehensive analysis, a multicast service is carried by only one RE. Each cellular base station transmits the same multicast service, which is carried on the subcarrier. Multicast services on express, represents base station f L The signal carried on subcarrier n in the multicast service sent, assuming that the multicast service The set of receiving terminal users is expressed as For end users In subcarrier The multicast service signal of the cellular base station received on the cellular base station can be expressed as:

[0440]

[0441] The first term of the formula represents the signal received by the terminal user k from the base station within the multipath delay range and carried on the subcarrier The multicast signal on the receiver is received by diversity. The second item indicates that the base station received by the terminal user k is not within the multipath delay range of the transmitted signal and is carried on the subcarrier The receiver regards this part of the signal as interference. The third item indicates that the terminal user The noise received meets Indicates that the noise satisfies the mean of 0 and the variance is N0Δf L is a complex Gaussian distributed random variable, and N0 represents the one-sided power spectral density of the noise.

[0442] The signal to interference and noise ratio of the cellular base station multicast service signal is calculated based on the cellular base station multicast service signal.

[0443] End User Receive broadcast services on subcarriers Receive multicast services from cellular base stations The signal-to-interference-noise ratio can be expressed as:

[0444]

[0445] in Indicates the interference on the same subcarrier from adjacent base stations.

[0446]

[0447] Indicates the inter-carrier interference caused by the high-speed movement of the terminal.

[0448]

[0449] The minimum value of the multicast service transmission rate of the cellular base station is calculated based on the signal to interference and noise ratio of the multicast service signal of the cellular base station.

[0450] End User In subcarrier Receive multicast services from cellular base stations The rate can be expressed as:

[0451]

[0452] Cellular base station multicast service The transmission rate is the receiving multicast service End users The minimum value in can be expressed as:

[0453]

[0454] The transmission rate of the multicast service of the service transmission system can be expressed as:

[0455]

[0456] For the transmission of multicast services, the minimum transmission rate of the system multicast services can be set according to the actual terminal user service requirements. That is, there are the following constraints:

[0457]

[0458] The maximum value of the cellular base station unicast service transmission rate is calculated based on the minimum value of the broadcast tower broadcast service transmission rate and the minimum value of the cellular base station multicast service transmission rate.

[0459] Unicast in the service transmission system is a two-way feedback communication between the base station and the end user, which is carried by the cellular base station. The bandwidth for carrying unicast services is β3w L , the number of subcarriers used to transmit unicast services is The subcarrier set is represented as Here, considering the ideal application situation, each subcarrier uses OFDMA to carry one terminal user data. Suppose subcarrier n carries unicast service information. The terminal user receiving the unicast service on subcarrier n is denoted as k n , at base station f L Coverage, end users The received unicast signal on the subcarrier can be expressed as:

[0460]

[0461] The first term of the formula represents the base station f LThe unicast information received by terminal user k in the coverage area on subcarrier n, the second term of the formula represents the neighboring base station f on subcarrier n L' Transmit to The third item indicates the unicast information of the terminal user on the subcarrier The noise received on At the end user k, it acts as interference. The received unicast signal to interference and noise ratio can be expressed as:

[0462]

[0463] in Indicates that the subcarrier from the adjacent cell Interference from adjacent cells.

[0464]

[0465] The second term in the denominator represents the self-carrier interference caused by the high-speed movement of the terminal. Here, the influence of Doppler frequency shift on the receiving end is quantified. d,max Indicates the maximum Doppler generated by the high-speed movement at the receiving end. All subcarriers are traversed using the variable j, expressed as:

[0466]

[0467] Then the transmission rate of terminal user k can be expressed as:

[0468]

[0469] The sum rate of the system transmitting unicast services can be obtained by summing the unicast receiving rates of all terminal users in the system. The sum rate of the system transmitting unicast services can be expressed as:

[0470]

[0471] The optimization goal of the model in the cellular network is to maximize the system unicast transmission rate while meeting the broadcast service transmission rate and multicast service transmission rate. The optimization problem is written as follows:

[0472]

[0473] The maximum transmission rate of the unicast service of the cellular base station can be obtained by combining them.

[0474] By adopting the technical solution in this embodiment, a service transmission system capable of broadcasting, multicasting, and unicasting is formed by combining a broadcast tower and a cellular base station, which satisfies both a larger coverage area and service transmission for high-speed mobile terminal users within the coverage area. The broadcast tower and the cellular base station are divided into multiple frequency domains corresponding to different services in the frequency domain, which reduces the bit error rate of the transmission system and ensures reliable reception of the transmission signal by the terminal user. And by controlling the adjustment of the transmission rate of the broadcast and multicast services, the transmission rate of the unicast service is kept in the optimal state, which improves the user experience of the terminal user and ensures the reasonable allocation of the resources of the service transmission system.

[0475] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations, and the various embodiments may be freely combined in different ways. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0476] It should be noted that, in the description of this specification, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this specification.

Claims

1. A service transmission system based on heterogeneous network deployment, characterized in that: include: A broadcast tower and a plurality of cellular base stations and a control system located within the coverage area of ​​the broadcast tower; The broadcast tower is used to undertake the broadcast services of terminal users within the coverage area whose moving speed is less than or equal to the preset speed, and the broadcast services of terminal users within the preset range from the broadcast tower whose moving speed is greater than the preset speed; The multiple cellular base stations are used to undertake broadcast services for other terminal users within the coverage area; The control system is used to: Calculating a minimum transmission rate corresponding to a first carrier bandwidth of the broadcast tower, where the first carrier bandwidth is used to bear broadcast services of terminal users within the coverage area whose moving speed is less than or equal to a preset speed; Calculating a minimum transmission rate corresponding to a second carrier bandwidth of the broadcast tower, where the second carrier bandwidth is used to bear broadcast services of terminal users within a preset range from the broadcast tower and whose moving speed is greater than a preset speed; Calculating a minimum transmission rate of the broadcast tower broadcast service based on a minimum transmission rate corresponding to the first carrier bandwidth and a minimum transmission rate corresponding to the second carrier bandwidth; respectively calculating a minimum transmission rate corresponding to a broadcast service and a minimum transmission rate corresponding to a multicast service of the cellular base station; Based on the minimum transmission rate of the broadcast tower broadcast service, the minimum transmission rate corresponding to the cellular base station broadcast service, and the minimum transmission rate corresponding to the cellular base station multicast service, the maximum value of the cellular base station unicast service transmission rate is calculated.

2. The service transmission system based on heterogeneous network deployment according to claim 1, characterized in that: The multiple cellular base stations are also used to undertake multicast services for all terminal users within the coverage area.

3. The service transmission system based on heterogeneous network deployment according to claim 2, characterized in that: The multiple cellular base stations are also used to undertake unicast services for all terminal users within the coverage area.

4. A service transmission method based on heterogeneous network deployment, characterized in that: include: Setting a broadcast tower, the broadcast tower is used to undertake the broadcast services of terminal users whose moving speed is less than or equal to a preset speed within the coverage area, and the broadcast services of terminal users whose moving speed is greater than the preset speed within a preset range from the broadcast tower; Setting a plurality of cellular base stations, wherein the plurality of cellular base stations are all located within the coverage area, and the plurality of cellular base stations are used to undertake broadcast services for other terminal users within the coverage area; Controlling the transmission rates of the broadcast service and the multicast service to be minimum so as to maximize the transmission rate of the unicast service includes: Calculating a minimum transmission rate corresponding to a first carrier bandwidth of the broadcast tower, where the first carrier bandwidth is used to bear broadcast services of terminal users within the coverage area whose moving speed is less than or equal to a preset speed; Calculating a minimum transmission rate corresponding to a second carrier bandwidth of the broadcast tower, where the second carrier bandwidth is used to bear broadcast services of terminal users within a preset range from the broadcast tower and whose moving speed is greater than a preset speed; Calculating a minimum transmission rate of the broadcast tower broadcast service based on a minimum transmission rate corresponding to the first carrier bandwidth and a minimum transmission rate corresponding to the second carrier bandwidth; respectively calculating a minimum transmission rate corresponding to a broadcast service and a minimum transmission rate corresponding to a multicast service of the cellular base station; Based on the minimum transmission rate of the broadcast tower broadcast service, the minimum transmission rate corresponding to the cellular base station broadcast service, and the minimum transmission rate corresponding to the cellular base station multicast service, the maximum value of the cellular base station unicast service transmission rate is calculated.

5. The service transmission method based on heterogeneous network deployment according to claim 4, characterized in that: The multiple cellular base stations are also used to undertake multicast services for all terminal users within the coverage area.

6. The service transmission method based on heterogeneous network deployment according to claim 5, characterized in that: The multiple cellular base stations are also used to undertake unicast services for all terminal users within the coverage area.

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