Side-chain communication resource allocation method based on resource hopping

Abstract

The present invention discloses a side-chain communication resource allocation method based on resource hopping, which mainly solves the problems of resource conflict and communication failure caused by users independently selecting communication resources in existing distributed D2D networks. The implementation solution is as follows: store the security capability value of users during the establishment of a direct communication link; divide physical resources into time-frequency resource blocks through sub-channels and sub-frames; randomly select an initial time-frequency resource block and use the security capability value as a user feature; according to a given time-frequency hopping pattern, pre-configure communication resources for users based on the random initial resources and user features, and record them as an index set; when a user needs to send data, query the physical resource block to be used in the current period according to the index and send data on the specified physical resource block. The present invention reduces the number of resource conflicts, alleviates the resource conflict problem in a decentralized D2D network, improves the communication success rate, and avoids continuous blocking conflicts. It can be used for the communication resource allocation of a decentralized D2D network.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication, and further relates to a communication resource allocation method, which can be used for a centerless sidechain network under the 3GPP standard. Technical Background

[0002] In emergency communication scenarios, the application requirements for direct communication between devices and even flexible networking are increasing day by day. As an important stage in the evolution of the self-organizing network based on the 3rd Generation Partnership Project (3GPP) standard, the centerless device-to-device (D2D) network can achieve direct transmission between user equipments by adopting sidechain transmission technology, and thus has received extensive attention. In 2012, 3GPP Release 12 (Rel-12) began to support direct communication between user equipments (UEs), that is, UEs directly exchange data and signaling services using the sidechain protocol.

[0003] The sidechain-based D2D communication realizes the direct transmission of data between users by multiplexing the cellular network resources, which can effectively reduce the transmission power, improve the resource utilization rate, increase the system capacity, reduce the end-to-end transmission delay, and reduce the base station load. In addition, compared with traditional short-distance wireless communication technologies, the D2D communication under cellular network management can establish a more reliable transmission link in an environment with controllable interference. Therefore, the D2D communication technology under cellular network can not only improve the performance of the original cellular network, but also serve emerging applications such as massive machine-type communication, and is an emerging wireless communication technology with great application prospects.

[0004] Although the centerless D2D network has advantages such as fast networking and independence from infrastructure, the existing 3GPP standard is not designed for a distributed architecture. Therefore, in centerless D2D communication, the possibility of potential communication link establishment conflict problems and resource conflict problems in the data transmission stage increases greatly. Under the centerless D2D network based on sidechain, D2D users will completely independently implement the communication link establishment process and independently select time-frequency resource blocks for data transmission. Therefore, there are problems such as a high probability of communication link establishment conflict, low resource allocation efficiency, and poor performance.

[0005] The 3GPP standard TS 36.331 stipulates a resource allocation scheme in which UEs randomly obtain time-frequency resource blocks from a reserved resource pool [1]. However, the random resource allocation scheme has low resource utilization rate and weak scalability, and there will be relatively serious resource conflict problems as the number of nodes increases.

[0006] Most existing resource allocation schemes for D2D communication mainly consider relying on a centralized controller for resource scheduling. Such schemes usually assume that the channel state information is known. However, in a decentralized D2D network, the UEs lack physical layer feedback and centralized control, making it difficult to collect sufficient information to maximize the performance of the entire network system. Therefore, this assumption is not applicable to decentralized D2D networks. Secondly, the computing power of UEs is relatively weak and they are more sensitive to power consumption compared to base stations. Existing complex resource allocation schemes cannot be executed on UEs due to limitations in computing power and battery capacity. Therefore, to achieve communication in a decentralized D2D network, it is crucial to develop lightweight and distributed resource allocation schemes.

[0007] WANG et al. studied a set of distributed resource allocation schemes for out-of-coverage scenarios in "Distributed resource allocation schemes for out-of-coverage D2D communications". However, in this scheme, the UEs select time-frequency resources for communication based on random allocation or interference awareness, resulting in a relatively high probability of packet collisions and thus a low communication success rate. In addition, the signaling overhead of this scheme is relatively large, and it will also have a certain impact on security and reliability.

[0008] In summary, in existing decentralized D2D networks, due to the inherent interference phenomenon and the broadcast nature of the wireless channel, that is, interference will occur whenever multiple UEs send data in the same resource, there are two main challenges for distributed resource allocation schemes: half-duplex constraints and resource selection conflicts.

[0009] The so-called half-duplex constraint means that a device cannot send and receive data simultaneously. Since sending while receiving will introduce strong self-interference and the cost of eliminating interference is very high, 3GPP recommends that D2D communication adopt a half-duplex communication mode. However, if multiple UEs operating in the half-duplex mode select resource blocks in the same subframe in the resource pool to send data packets, they will not be able to receive the data packets sent by the other party.

[0010] The so-called resource selection conflict: when selecting communication resources using resource allocation mode 2 specified in 3GPP, since there is no feedback mechanism introduced for the D2D scenario in the 3GPP Rel-15 technical specification, the UEs in a decentralized D2D network cannot obtain the global information and resource allocation situation of the network. When different UEs select the same resource block to send data packets, interference will occur on this resource block, resulting in the receiving UE being unable to correctly decode the information and the message reception failing.

[0011] From this, it can be seen that there is an urgent need to design a reasonable resource allocation scheme for decentralized D2D networks. Summary of the Invention

[0012] The present invention aims at the deficiencies of the above-mentioned prior art and proposes a side-chain communication resource allocation method based on resource hopping to reduce the probability of resource conflicts in a decentralized D2D network, improve the probability of correct data reception by the UE, and avoid communication blockage caused by occasional conflicts.

[0013] To achieve the above object, the technical idea of the present invention is as follows: resource pre-configuration is realized through specific hopping patterns in the time domain and frequency domain of communication resources to solve the problem of resource conflicts in a decentralized D2D network. At the same time, by introducing the security mode capability value, the resource hopping scheme has deterministic user characteristics, and the hopping rules of different users are differentiated through random initialization and user characteristics to avoid continuous resource conflicts caused by different users adopting the same hopping pattern.

[0014] According to the above technical idea, the implementation steps of the present invention are as follows:

[0015] (1) Two users, UE1 and UE2, establish a side-chain direct communication link on the PC5 interface through the process defined in the standard TS 36.331, and extract and store the 2-byte security capability index k in the security mode setting during the link establishment process.

[0016] (2) Divide the communication cycle into N T sub-frames, divide the frequency band used by the decentralized D2D network into N F parallel channels, and form N T ×N F physical time-frequency resource blocks, denoted as the index pair (i, j), where i represents the frequency domain index of the physical resource block, ranging from 0 to N F -1, and j represents the time domain index of the physical resource block, ranging from 0 to N T -1.

[0017] (3) Select a logical resource from the available communication resource pool as the communication resource and establish a mapping association between it and N T ×N F time-frequency resource blocks.

[0018] (4) Select the physical resource block (i(0), j(0)) for initial communication by randomly selecting the initial frequency domain index i(0) and time domain index j(0).

[0019] (5) Set two hopping rules for the resource block indexes i(t) and j(t) used when sending data packets in the t-th communication cycle:

[0020] Hopping rule 1:

[0021] i(t) = (i(0) + kt) mod N F

[0022] j(t) = (j(0) + mod(t + k, N T ) i(0) ) mod N T

[0023] Hopping rule 2:

[0024] i(t) = (i(0) + kt) mod N F

[0025] j(t) = (j(0) + (c0, c1, …, c r-1 ) b(t) + mod(t + k, N T ) i(0) ) mod N T

[0026] where N T is an odd prime number and N T < N F , i ∈ {1, 2, …, N F - 1}, j ∈ {0, 1, …, N T - 1}, the value of k is the security capability value obtained during the link establishment process, and the maximum value is max(N F - 1, N T - 1), r is the smallest integer greater than or equal to , b(t) is N T a column vector in the r - order extended prime field (c0, c1, …, c r-1 ) represents a row vector, satisfying i(0) = c0 + c1N T + … + c r-1 N T r-1 ;

[0027] (6) Arbitrarily select Hopping rule 1 or Hopping rule 2 to construct the time - frequency index set {(i(t), j(t))} of the logical communication resources and physical communication resources in any subsequent communication cycle t∈Z ;

[0028] (7) Use the physical resources specified by the time - frequency index set {(i(t), j(t))} t∈Z for communication.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] First, based on the 3GPP protocol standard, the present invention provides a feasible solution for D2D communication resource allocation under the standard framework, enabling the allocated resources to achieve time-domain and frequency-domain hopping, reducing the probability of resource conflicts in distributed D2D network communication, and improving the communication success rate.

[0031] Second, the present invention uses the security mode identification k value in the 3GPP standard D2D communication link establishment process as the private feature of the user pair, saving the signaling overhead for the communication parties to communicate the resource hopping pattern.

[0032] Third, by introducing changes in the k value, the present invention makes the above resource hopping pattern have user characteristics, thus solving the continuous conflict problem when different users select the same time-frequency resource block to transmit data.

[0033] Fourth, the time-frequency hopping pattern given by the present invention has a relatively long period in terms of row periodicity and column periodicity compared with the prior art, which can not only avoid the influence caused by channel changes due to fast fading, but also avoid periodic resource conflicts. Description of the Drawings

[0034] Figure 1 is the implementation flowchart of Embodiment 1 of the present invention;

[0035] Figure 2 is the implementation flowchart of Embodiment 2 of the present invention;

[0036] Figure 3 is the probability simulation comparison diagram of at least one successful communication between the present invention and the existing method;

[0037] Figure 4 is the communication success probability simulation comparison diagram between the present invention and the existing method;

[0038] Figure 5 is the resource conflict times simulation comparison diagram between the present invention and the existing method. Detailed Embodiment

[0039] The following further elaborates on the embodiments and effects of the present invention in conjunction with the drawings.

[0040] To address the challenges brought by resource conflicts in the existing 3GPP sidelink standard, the present invention proposes two implementation methods for sidelink communication resource allocation based on resource hopping.

[0041] Embodiment 1:

[0042] Refer to Figure 1 , the implementation steps of this example are as follows:

[0043] Step 1, establish a direct communication link and store the 2-byte security capability indicator k in the security mode setting.

[0044] In this step, two users, UE1 and UE2, establish a direct communication link on the side chain over the PC5 interface through the process defined in the standard TS 36.331. The specific implementation is as follows:

[0045] A user UE1 sends a direct communication request message DCRq to another user UE2, which contains the security capability value k of UE1 itself;

[0046] After receiving the DCRq message, user UE2 sets its own security capability value to k, stores and records this k value, and feeds back this k value to user UE1 through the direct security mode message DSMCm;

[0047] After receiving the DSMCm message, UE1 confirms that the security capability values of both sides are the same, stores and records the current security capability value k, and sends a direct security mode completion message DSMCp to UE2;

[0048] After receiving the DSMCp message, UE2 replies to UE1 with a direct communication acceptance message DCA to complete the link establishment.

[0049] Step 2: Divide the physical resource blocks and establish the indexes of the physical resource blocks.

[0050] Divide the communication cycle into N T sub - frames, and divide the frequency band used by the ad - hoc D2D network into N F parallel channels, forming N T ×N F physical time - frequency resource blocks, denoted as the index pair (i, j), where i represents the frequency - domain index of the physical resource block, ranging from 0 to N F - 1, and j represents the time - domain index of the physical resource block, ranging from 0 to N T - 1.

[0051] Step 3: Select communication resources and physical resource blocks, and set the hopping rules for the frequency - domain index i(t) and time - domain index j(t) of the resource blocks.

[0052] 3.1) Select an arbitrary logical resource from the available communication resource pool as the communication resource;

[0053] 3.2) Randomly select the initial frequency - domain index i(0) and time - domain index j(0), and determine the physical resource block (i(0), j(0)) for initial communication according to the selected frequency - domain index i(0) and time - domain index j(0).

[0054] 3.3) Set the hopping rules for the frequency - domain index i(t) and time - domain j(t) of the resource blocks used for sending data packets in the t - th communication cycle:

[0055] i(t) = (i(0) + kt) mod N F

[0056] j(t) = (j(0) + mod(t + k, N T ) i(0) ) mod N T

[0057] where N T is the number of sub - frames in a communication period and is also an odd prime number, N F is the number of parallel channels, and N T < N F , i ∈ {1, 2, …, N F - 1}, j ∈ {0, 1, …, N T - 1}, the value of k is the security capability value obtained during the link - establishment process, and the maximum value is max(N F - 1, N T - 1).

[0058] Step 4, construct a time - frequency index set and use physical resources for communication.

[0059] 4.1) Construct the time - frequency index set {(i(t), j(t))} of logical communication resources and physical communication resources in any subsequent communication period according to the above hopping rules t∈Z ;

[0060] 4.2) Use the physical resources specified by the time - frequency index set {(i(t), j(t))} t∈Z for communication:

[0061] 4.3) Before sending information, first query the current communication period number t, and then query the t - th element (i(t), j(t)) in the time - frequency index set {(i(t), j(t))} t∈Z ;

[0062] 4.4) According to the (i(t), j(t)) index, use the physical resource block in the i(t) - th sub - channel and the j(t) - th sub - frame for communication, that is, send data on this physical resource block.

[0063] Embodiment 2

[0064] Referring to Figure 2 , the implementation steps of this example are as follows:

[0065] Step 1, establish a direct communication link and store the 2 - byte security capability index k in the security mode setting.

[0066] The specific implementation of this step is the same as step 1 of Embodiment 1.

[0067] Step 2: Divide the physical resource blocks and establish the index of the physical resource blocks.

[0068] The specific implementation of this step is the same as step 2 in Embodiment 1.

[0069] Step 3: Select communication resources and physical resource blocks, and set the hopping rules for the frequency-domain index i(t) and time-domain index j(t) of the resource blocks.

[0070] 3a) The specific implementation of this step is the same as step 3.1) in Embodiment 1.

[0071] 3b) The specific implementation of this step is the same as step 3.2) in Embodiment 1.

[0072] 3c) Set the hopping rules for the frequency-domain index i(t) and time-domain index j(t) of the resource blocks used to send data packets in the t-th communication cycle:

[0073] i(t) = (i(0) + kt) mod N F

[0074] j(t) = (j(0) + (c0, c1,..., c r-1 )b(t) + mod(t + k, N T ) i(0) ) mod N T

[0075] where N T is the number of subframes in the communication cycle and is also an odd prime number, N F is the number of parallel channels, and N T < N F , i ∈ {1, 2,..., N F - 1}, j ∈ {0, 1,..., N T - 1}, the value of k is the security capability value obtained during the link establishment process, and the maximum value is max(N F - 1, N T - 1), r is the smallest integer greater than or equal to , b(t) is a column vector in the r-th extended prime field T formed by N , (c0, c1,..., c r-1 ) represents a row vector, and satisfies i(0) = c0 + c1N T +... + c r-1 N T r-1 .

[0076] Step 4: Construct the time-frequency index set and use the physical resources for communication.

[0077] The specific implementation of this step is the same as step 4 in Embodiment 1.

[0078] The effects of the present invention can be further illustrated by simulation:

[0079] I. Simulation Conditions

[0080] Simulation scenario: The proposed scheme of the present invention is simulated and verified on the MATLAB tool.

[0081] Path loss model: The calculation of path loss uses the model designed for the D2D scenario in 3GPP standard TR 36.843. The path loss of this model is: PL_B1_tot(d) = max(PL freespace (d), PL_B1(d)), where d represents the distance between UEs, PL freespace (d) represents the free space path loss, and PL_B1(d) represents the path loss of the line-of-sight transmission scenario defined by the Winner+B1 model.

[0082] Settings of other parameters: The transmission power of the UE is set to 23 dBm; the time domain period of the sidelink is 11 ms; the number of available RBs in the frequency domain is 44; the simulation process lasts for 150 sidelink communication periods; there are 483 UE devices in the ad-hoc D2D network; the system carrier frequency is 1930 GHz; the UE height is set to 1.5 m; the radius of the ad-hoc D2D network is 100 m; the SINR threshold is taken as 1.0 dB.

[0083] Comparison schemes: The following two are selected:

[0084] Comparison scheme 1: Adopt the resource hopping scheme described in 3GPP technical standard R1-133600. The resource block indices i(t), j(t) used for communication in the t-th time slot change according to the following rules:

[0085] i(t) = (i(0) + 3t) mod N F

[0086]

[0087] Comparison scheme 2: Adopt the resource hopping scheme described by Zhang et al. in On the hopping pattern design for D2D discovery. The resource block indices i(t), j(t) used for communication in the t-th time slot change according to the following rules:

[0088] i(t) = (i(0) + 3t) mod N T

[0089] j(t) = (j(0) + (c0, c1,..., c r-1 )b(t)) mod NT

[0090] Among them, the definitions of the row vector (c0, c1, …, c r-1 ) and the column vector b(t) can be found in Resource Hopping Pattern II proposed in the present invention.

[0091] II. Simulation Content and Results

[0092] Simulation 1: Under the above simulation parameters, the communication resource allocation is performed using the four methods of Embodiment 1, Embodiment 2, Comparative Scheme 1, and Comparative Scheme 2 of the present invention respectively, and the probabilities of at least one successful communication among these four methods are compared. The results are as Figure 3 ,

[0093] It can be seen from Figure 3 that the communication success rates of Comparative Scheme 1 and Comparative Scheme 2 no longer change after three hopping periods. Although the comparative schemes optimize the half-duplex problem, they cannot effectively solve the resource conflict problem, resulting in their communication success rates being lower than those of Embodiment 1 and Embodiment 2 of the present invention.

[0094] In addition, as the communication cycle increases, the probabilities of at least one successful communication between Embodiment 1 and Embodiment 2 in the present invention approach 1. This is because the two resource hopping patterns proposed in the present invention introduce the change of the k value, making the resource hopping rules between different users different, thus solving the problem of periodic continuous conflicts caused by initial resource conflicts.

[0095] Simulation 2: Under the above simulation parameters, the communication resource allocation is performed using the four methods of Embodiment 1, Embodiment 2, Comparative Scheme 1, and Comparative Scheme 2 of the present invention respectively, and the communication success rates of these four methods are compared. The results are as Figure 4 ,

[0096] It can be seen from Figure 4 that the communication success rate curves of Comparative Scheme 1 and Comparative Scheme 2 no longer change after the 11th cycle and the 121st cycle respectively. Since the column period of Comparative Scheme 1 is 11, the time-domain resources of users show periodic changes after the 11th cycle. And the column period of Comparative Scheme 2 is 121, so the time-domain resources of users under this scheme show periodic changes after the 121st cycle. Therefore, the communication success rates of Comparative Scheme 1 and Scheme 2 reach their limits at the 11th cycle and the 121st cycle respectively, and then it is impossible to communicate with new users.

[0097] In the first embodiment of the present invention and Comparative Scheme 1, the column period is 11. Since the frequency-domain change is introduced in the first embodiment of the present invention, the time-frequency resource blocks of users can be changed more variably, and the communication success rate in this mode is improved compared with Comparative Scheme 1. Compared with the first embodiment of the present invention, in the second embodiment of the present invention, since the column period of the second embodiment is longer, the communication success rate of the second embodiment can be further improved after the 11th cycle until it is impossible to communicate with new users after the 121st communication cycle.

[0098] Simulation 3: Under the above simulation parameters, the communication resource allocation is performed using the four methods of the first embodiment, the second embodiment of the present invention, Comparative Scheme 1, and Comparative Scheme 2, respectively, and the number of resource conflicts of these four methods is compared. The results are as Figure 5 ,

[0099] As can be seen from Figure 5 , when the number of users is less than or equal to the total number of time-frequency resource blocks, there are resource conflict situations. This is because the users adopt a distributed resource allocation scheme. Due to the lack of centralized control, there are resource conflicts when independently selecting the time-frequency resource blocks for transmission. When the number of users is less than the number of time-frequency resource blocks, the resource conflict situations of Comparative Scheme 1 and Comparative Scheme 2 are not serious, so the advantages of the first embodiment and the second embodiment of the present invention are not obvious. However, as the number of users increases, the resource conflict situations of Comparative Scheme 1 and Comparative Scheme 2 become serious, while the first embodiment and the second embodiment of the present invention can effectively reduce the number of resource conflicts.

[0100] In summary, the present invention can reduce the number of resource conflicts, prevent blocking conflicts, and improve the communication success rate of the distributed D2D communication system.

Claims

1. A side-chain communication resource allocation method based on resource hopping, characterized in that It includes the following steps: (1) Two users, UE1 and UE2, establish a sidelink direct communication link on the PC5 interface through the process defined in standard TS 36.331, and extract and store the 2-byte security capability indicator k in the security mode setting during the link establishment process; (2) Divide the communication cycle into N T sub - frames, and divide the frequency band used by the ad - hoc D2D network into N F parallel channels, forming N T ×N F physical time - frequency resource blocks, denoted as index pairs (i, j), where i represents the frequency - domain index of the physical resource block, ranging from 0 to N F - 1, and j represents the time - domain index of the physical resource block, ranging from 0 to N T - 1; (3) Select an arbitrary logical resource from the available communication resource pool as the communication resource, and establish a mapping association between it and N T × N F time-frequency resource blocks; (4) By randomly selecting the initial frequency-domain frequency index i(0) and time-domain index j(0), select the physical resource block (i(0), j(0)) for initial communication; (5) Set two hopping rules for the resource block indices i(t) and j(t) used when sending data packets in the t-th communication cycle: Hopping rule 1: i(t) = (i(0) + kt) mod N F j(t) = (j(0)+mod(t + k,N T ) i(0) ) mod N T Hopping rule 2: i(t) = (i(0) + kt) mod N F j(t) = (j(0)+(c0,c1,…,c r-1 )b(t)+mod(t + k,N T ) i(0) )mod N T where N T is an odd prime number and N T < N F , i ∈ {1, 2, …, N F - 1}, j ∈ {0, 1, …, N T - 1}, the value of k is the security capability value obtained during the link establishment process, and the maximum value is max(N F - 1, N T - 1), r is the smallest integer greater than or equal to , b(t) is a column vector in the T r - order extended prime field formed by N , (c0, c1, …, c r-1 ) represents a row vector, satisfying i(0) = c0 + c1N T +... + c r-1 N T r-1 ; (6) Arbitrarily select hopping rule 1 or hopping rule 2 to construct the time-frequency index set {(i(t), j(t))} of logical communication resources and physical communication resources in any subsequent communication cycle t∈Z ; Use the time-frequency index set {(i(t), j(t))} t∈Z to communicate over the specified physical resources.

2. The method according to claim 1, characterized in that: The link establishment process described in step (1) is that one user, UE1, sends a direct communication request message DCRq to another user, UE2. After receiving the DCRq message, the UE2 user replies with a direct security mode message DSMCm to the UE1 user. After receiving the DSMCm message, UE1 sends a direct security mode completion message DSMCp to UE2. After receiving the DSMCp message, UE2 replies with a direct communication acceptance message DCA to complete the link establishment.

3. The method according to claim 1, wherein: The security capability identifier k is extracted during the link establishment process in step (1). The user UE1 notifies the user UE2 of its own security capability value k through the direct communication request message DCRq. After receiving the DCRq message, the user UE2 sets its own security capability value to k, stores and records this k value, and feeds back this k value to the user UE1 through the direct security mode message DSMCm. UE1 confirms that the security capability values of both parties are the same through the DSMCm message and stores and records the current security capability value k.

4. The method according to claim 1, characterized in that: The logical resource described in step (3) refers to a virtual resource with the same size as the physical resource block. The logical resource block VRB and the physical resource block PRB correspond to their respective resource block numbers nVRB and nPRB. The number nPRB of the physical resource block PRB is sequentially numbered according to the physical position in the frequency domain. The number nVRB of the logical resource block VRB is the logical number indicated during system resource allocation, and the actual physical resource position is determined through the mapping relationship between the logical number nVRB and the physical resource block number nPRB.

5. The method according to claim 1, characterized in that: The column vector b(t) in hopping rule 2 described in step (5) is defined as follows: Among them, B is any constant column vector in which is an r-order extended prime field formed by N T , and A is a matrix over the prime field , expressed as: where a i is the i-th element in the prime field 6. The method according to claim 1, wherein: When used in step (7), use the time-frequency index set {(i(t), j(t))} t∈Z Perform communication with the specified physical resources as follows: (7a) Before sending the information, first query the current communication cycle number t, and then query the t-th element (i(t), j(t)) in the time-frequency index set {(i(t), j(t))} t∈Z ; (7b) Locate the physical resource block at the i(t)-th subchannel and the j(t)-th subframe according to the (i(t), j(t)) index, and send data on this physical resource block.

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