On-demand rate segmentation assisted semi-unlicensed transmission method and device

Abstract

The invention discloses a semi-unlicensed transmission method and device assisted by on-demand rate segmentation, and belongs to the technical field of wireless communication, a base station selects an optimal one from unlicensed users as a target user under a corresponding frequency spectrum according to the relationship between the interference gain of the unlicensed users and the interference threshold value, and transmits the selected optimal one to the unlicensed users. According to the method, the GFU with various different target rate requirements can be better taken into account, the GFU is segmented and accessed according to the required rate after the conditions are met, and the GFU is embedded into the spectrum hole of the hole GBU, so that extra interference on the existing active GBU is avoided. In addition, if a target user selected in each frequency spectrum needs rate segmentation, the target user firstly carries out message segmentation and then carries out data transmission with the base station, that is, the GFU message is flexibly split into a plurality of data streams, and transmission power is optimally allocated to each data stream, so that the access interruption probability can be obviously reduced, and the access efficiency can be improved. And the achievable rate of the GFU is maximized.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication, and more specifically, relates to a semi-grant-free transmission method and apparatus assisted by rate splitting on demand. Background Art

[0002] The Internet of Everything (IoE) has become an important development direction in the communication industry, and most terminal devices will be connected to the network in the future. Facing a large number of Internet of Things devices, traditional grant-based (GB) transmission solutions will face major challenges. On the one hand, due to limited preamble sequence resources, for example, there are only 64 orthogonal preambles for random access (RA) in LTE, which is far less than the number of devices expected to be connected by the Internet of Things, and it is bound to cause serious user collision problems. On the other hand, the data packets generated by Internet of Things devices are very short, often showing strong fragmentation and sparsity. Traditional GB transmission is not applicable due to the signaling overhead and delay generated by the handshake process. To address the above challenges, 3GPP proposed a grant-free (GF) transmission scheme in 2016, which allows devices to access without a long handshake protocol, thus effectively reducing transmission delay and improving resource block utilization efficiency.

[0003] To achieve higher spectral efficiency, recently, the concept of GF RA in large-scale MIMO based on NOMA has been proposed in the literature. In traditional GF RA, pilots and data are time-division multiplexed, which means that pilot and data transmissions cannot occur simultaneously. NOMA-based GF RA utilizes the good propagation characteristics of large-scale MIMO and allows two different device groups to transmit pilots and data simultaneously in each time slot. This greatly improves the resource utilization rate of pilot and data transmissions.

[0004] Although a large amount of innovative work has been carried out and many NOMA-assisted SGF transmission schemes have been proposed, the existing SGF transmission schemes still have the technical problem of incompatibility between the total system capacity and the outage probability. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement requirements of the prior art, the present invention provides a semi-grant-free transmission method and apparatus assisted by rate splitting on demand, aiming to solve the technical problem of incompatibility between the total system capacity and the outage probability of the prior art.

[0006] To achieve the above object, according to one aspect of the present invention, a semi-grant-free transmission method assisted by rate splitting on demand is provided, including:

[0007] S1: The base station broadcasts a preamble;

[0008] S2: The authorized users and unauthorized users estimate their own channel state information using the preamble; and the authorized users feedback their communication state information to the base station, including: their own transmission power, channel state information, and spectrum state;

[0009] S3: The base station selects the communication state information of the authorized users with an idle spectrum state from the received communication state information to calculate the interference gain of each idle authorized user, and broadcasts it as a dynamic interference threshold to all unauthorized users;

[0010] S4: The base station selects one unauthorized user from each unauthorized user in each spectrum as the target user for the corresponding spectrum according to the relationship between the interference gain of each unauthorized user and the interference threshold in each spectrum;

[0011] S5: Perform rate splitting on the target users of each spectrum as needed to transmit data with the base station;

[0012] S6: After the base station receives the data transmissions from all users, it decodes the first several authorized users with the target rate sorted from large to small using the serial interference cancellation decoding method based on the channel state information until there is one remaining undecoded authorized user; then it decodes the last undecoded authorized user and all unauthorized users using the hybrid serial interference cancellation decoding scheme.

[0013] Further, the S4 includes: comparing the interference gain of each unauthorized user in each spectrum with the interference threshold, and calculating the cross-interference between the channel vectors of each unauthorized user with an interference gain lower than any interference threshold and the channel vectors of the authorized users in each occupancy state; selecting the unauthorized user corresponding to the minimum cross-interference calculation result as the target user for the corresponding spectrum. with the channel vectors of the authorized users in each occupancy state respectively perform cross-interference calculation; select the unauthorized user with the minimum cross-interference calculation result as the target user for the corresponding spectrum.

[0014] Further, the comparison between the interference gain of each unauthorized user and the interference threshold includes: using τ i =P|h i BI | 2 calculate the interference threshold corresponding to i idle authorized users, and use the formula to calculate the interference gain of the jth unauthorized user; then compare and the two; where P is the transmission power of the authorized user, is the transmission power of the unauthorized user, is the channel state information of the ith idle authorized user, is the channel state information of the j-th grant-free user; |.| represents modulo.

[0015] Further, the channel vectors of each grant-free user below the interference threshold and the channel vectors of the authorized users in each occupancy state are respectively subjected to mutual interference calculation, including: using to calculate the mutual interference calculation result of the channel vector of the j-th grant-free user below the interference threshold and the channel vector of the i-th authorized user in the occupancy state Identifies the j-th grant-free user below the interference threshold, T i BA The i-th authorized user in the occupancy state, MI represents mutual interference calculation, |.| represents modulo.

[0016] Further, the S5 includes: when the target rate of the target user is greater than the target rate of the authorized user, it is regarded as being in Scenario 1, and in Scenario 1, rate splitting is first performed and then data transmission is carried out with the base station; when the target rate of the target user is lower than the target rate of the authorized user, it is regarded as being in Scenario 2, and in Scenario 2, direct data transmission is carried out with the base station.

[0017] Further, the achievable rate R of the target user after embedding in Scenario 1 I,F is expressed as follows:

[0018]

[0019] where represents the communication situation of the target user after embedding in Scenario 1 as and when the achievable rate; represents the communication situation of the target user after embedding in Scenario 1 as when the achievable rate; represents the communication situation of the target user after embedding in Scenario 1 as c = 0, when the achievable rate; is the channel state information of the target user; is the channel state information of the i-th idle authorized user; is the power of the target user; P is the power of the authorized user; set threshold is the channel state information of the authorized user with the minimum channel gain; intermediate variable R B is the target rate of the authorized user.

[0020] Furthermore, the outage probability of the target user under Scenario I has the following expression:

[0021]

[0022] where the intermediate variables A, B, and C are respectively Intermediate variable R F is the target rate of the target user, and η B is the ratio of ν B to P, and η F is the ratio of ν F is the ratio of.

[0023] Furthermore, the achievable rate R of the target user after embedding under Scenario 2 II,F is expressed as follows:

[0024]

[0025] where represents the achievable rate when the communication situation of the target user after embedding under Scenario 2 is and ; represents the achievable rate when the communication situation of the target user after embedding under Scenario 2 is ; represents the achievable rate when the communication situation of the target user after embedding under Scenario 2 is c = 0; is the channel state information of the target user; is the channel state information of the i-th idle authorized user; is the power of the target user; P is the power of the authorized user; the set threshold is the channel state information of the authorized user with the minimum channel gain; intermediate variable R B is the target rate of the authorized user.

[0026] Furthermore, the outage probability of the target user under Scenario 2 has the following expression:

[0027]

[0028] where the intermediate variable Intermediate variable Intermediate variable Intermediate variable R Fis the target rate for the target user, η B is ν B the ratio of η to P F is ν F is the ratio of

[0029] According to another aspect of the present invention, there is provided a semi-persistent grant-free transmission system assisted by on-demand rate splitting, including: a base station and a user terminal, configured to execute the above-mentioned semi-persistent grant-free transmission method assisted by on-demand rate splitting.

[0030] Generally speaking, compared with the prior art by the above technical solution conceived by the present invention, the following beneficial effects can be achieved:

[0031] (1) The present invention provides a semi-persistent grant-free transmission method assisted by on-demand rate splitting. The base station selects one of the grant-free users in each spectrum as the target user under the corresponding spectrum according to the relationship between the interference gain of each grant-free user in each spectrum and the interference threshold, which can better take care of more GFUs that can meet the access conditions, and the GFU is embedded in the spectrum hole of the hole GBU without causing additional interference to the existing GBU. Perform rate splitting on the target user of each spectrum as needed for data transmission with the base station; the GFU message can be flexibly split into multiple data streams, and the transmission power is optimally allocated for each data stream, significantly reducing the access interruption probability and maximizing the achievable rate of the GFU.

[0032] (2) In this solution, the GB group selects grant-free users that meet the dynamic interference level in a broadcast form, while the grant-free users actively select the GB spectrum with the minimum mutual interference (MI) according to their own channel conditions.

[0033] (3) This solution can perform rate splitting on demand according to the differentiated rate requirements of GFUs. By flexibly splitting the GFU message into multiple data streams and optimally allocating the transmission power for each data stream to maximize the achievable rate of the GFU. Splitting the message of the GFU with high rate requirements is called scenario I, while the GFU without specific rate requirements is treated as a special case without RS, defined as scenario II. This method not only further improves the access fairness of the GFU, but also makes full use of the advantages of RSMA.

[0034] (4) This solution derives a closed-form solution for the access interruption probability of GFU based on embedded access and on-demand rate splitting, and verifies the correctness of the derived closed-form solution through Monte Carlo simulation. It has universality and can be flexibly applied to various wireless communication transmission schemes. Description of the Drawings

[0035] Figure 1It is the flowchart of the semi-persistent grant-free transmission method assisted by rate splitting on demand provided in Embodiment 1 of the present invention;

[0036] Figure 2 It is the flowchart of the semi-persistent grant-free transmission protocol based on EADS provided in Embodiment 1 of the present invention;

[0037] Figure 3 It is the flowchart of the composite successive interference cancellation decoding algorithm provided in Embodiment 1 of the present invention;

[0038] Figure 4a and Figure 4b It is the simulation diagram of the outage probability of the grant-free user under different methods in Scenario 1 provided in Embodiment 1 of the present invention;

[0039] Figure 5a and Figure 5b It is the simulation diagram of the outage probability of the grant-free user under different methods in Scenario 2 provided in Embodiment 1 of the present invention;

[0040] Figure 6a and Figure 6b It is the simulation diagram of the outage probability of the licensed user under different methods provided in Embodiment 1 of the present invention

[0041] Figure 7a and Figure 7b It is the simulation diagram of the system sum rate corresponding to Scenario 1 and Scenario 2 respectively provided in Embodiment 1 of the present invention;

[0042] Figure 8 It is the model diagram of the semi-persistent grant-free transmission system assisted by rate splitting on demand provided in Embodiment 2 of the present invention. Detailed implementation manners

[0043] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0044] Embodiment 1

[0045] This embodiment provides a semi-persistent grant-free transmission method assisted by rate splitting on demand, as Figure 1 and Figure 2 shown, including: S1 - S6.

[0046] S1: The base station broadcasts a preamble.

[0047] S2: The authorized users and unauthorized users estimate their own channel state information using preambles; and the authorized users feedback their communication state information to the base station, including: their own transmission power, channel state information, and spectrum state.

[0048] S3: The base station selects the communication state information of the authorized users with an idle spectrum state from the received communication state information to calculate the interference gain of each idle authorized user, and broadcasts it as a dynamic interference threshold to all unauthorized users.

[0049] S4: The base station selects one unauthorized user from each unauthorized user in each spectrum as the target user for the corresponding spectrum according to the relationship between the interference gain and the interference threshold of each unauthorized user in each spectrum.

[0050] S5: Perform rate splitting on the target users of each spectrum as needed for data transmission with the base station.

[0051] S6: After the base station receives the data transmissions of all users, it decodes the first several authorized users sorted from largest to smallest in target rate using the serial interference cancellation decoding method based on channel state information until there is one remaining undecoded authorized user; then it decodes the last undecoded authorized user and all unauthorized users using the hybrid serial interference cancellation decoding scheme.

[0052] The semi-unlicensed uplink transmission scenario provided by this embodiment is as follows: Among them, unauthorized users are allowed to access the GB channel through the semi-unlicensed protocol. Specifically, assume there are N users, denoted as: These users need to be served with high priority and adopt the GB transmission protocol. Are allocated dedicated orthogonal frequency bands, denoted as f c . Multiple authorized users share the licensed spectrum using NOMA technology. Since authorized users are usually idle most of the time, the semi-unlicensed protocol allows some unauthorized users to opportunistically access the idle authorized user channels, while the remaining unauthorized users continue to stay in their reserved resource blocks. In this way, the spectral efficiency of the GB channel is improved while reducing the conflicts among the remaining unauthorized users.

[0053] Since unauthorized users access the idle licensed spectrum in an opportunistic manner, considering that authorized users and unauthorized users have different QoS requirements (i.e., authorized users are usually users sensitive to delay and with low rate requirements, while unauthorized users are usually users tolerant to delay and with high rate requirements), there may be a situation where the spectrum holes of authorized users cannot meet the high rate requirements of unauthorized users. In this case, unauthorized users need to perform rate splitting. Therefore, we divide the user scenario into two categories, as Figure 1As shown. Scenario 1 includes unlicensed users with RS, whose rate requirements generally exceed those of a single idle licensed user and only need to access after RS. Scenario 2 consists of unlicensed users without specific rate requirements, and they do not need RS. Suppose there are M unlicensed users, denoted as They compete with each other in an opportunistic access manner to access the licensed spectrum. Suppose all users are equipped with a single antenna. is a licensed user accessing the licensed spectrum through the GB transmission protocol. Therefore, before communicates with the base station, traditional handshake signaling is performed.

[0054] Due to the signaling limitations of the unlicensed transmission protocol, the BS cannot obtain 's channel state information, while the NOMA-assisted semi-unlicensed transmission protocol allows selected to join the GB band and perform superimposed transmission with . Therefore, it can be assumed that the BS has a sufficient number of orthogonal preambles to obtain the channel state information of the transmitted , which is beneficial to multi-user detection. Suppose the channel of the licensed user is represented as showing independent and identically distributed Rayleigh fading. The channel gains of the licensed user and the unlicensed user are arranged in ascending order, denoted as

[0055] Since there may be multiple active licensed users sharing the licensed spectrum with multiple unlicensed users, in order to ensure the QoS performance of active licensed users and enhance transmission robustness, a composite successive interference cancellation algorithm is proposed. In this decoding scheme, first, the serial interference cancellation decoding method based on channel state information is used to decode the first N - 1 licensed users until there is one remaining undecoded licensed user (the Nth); then the Nth licensed user and all other unlicensed users are jointly applied with the hybrid serial interference cancellation decoding scheme. The flowchart of the decoding algorithm is as Figure 3 shown, Figure 3 which is the flowchart of the decoding algorithm for composite successive interference cancellation.

[0056] Table 1 shows the comparison between the semi-unlicensed protocol based on EADS proposed in the present invention and other existing classical protocols.

[0057] Table 1

[0058]

[0059] Furthermore, S4 includes: comparing the interference gain of each unlicensed user itself in each spectrum with the interference threshold, and for each unlicensed user whose interference gain is lower than any interference threshold, the channel vector with the channel vectors of the licensed users in each occupancy state Perform mutual interference calculations separately; the grant-free user corresponding to the minimum mutual interference calculation result is taken as the target user under the corresponding spectrum.

[0060] Further, compare the interference gain of each grant-free user with the interference threshold, including: using τ i = P|h i BI | 2 Calculate the interference threshold corresponding to i idle licensed users, and use the formula Calculate the self-interference gain of the j-th grant-free user; then compare and the two; where P is the transmit power of the licensed user, is the transmit power of the grant-free user, is the channel state information of the i-th idle licensed user, is the channel state information of the j-th grant-free user; |.| represents the modulus.

[0061] Further, perform mutual interference calculations on the channel vectors of each grant-free user below the interference threshold and the channel vectors of each licensed user in the occupied state separately, including: using Calculate the mutual interference calculation result of the channel vector of the j-th grant-free user below the interference threshold and the channel vector Identify the j-th grant-free user below the interference threshold, T i BA the i-th licensed user in the occupied state, MI represents the mutual interference calculation, and |.| represents the modulus.

[0062] Further, S5 includes: when the target rate of the target user is greater than the target rate of the licensed user, it is regarded as being in Scenario 1, and in Scenario 1, rate splitting is first performed and then data transmission is carried out with the base station; when the target rate of the target user is lower than the target rate of the licensed user, it is regarded as being in Scenario 2, and in Scenario 2, direct data transmission is carried out with the base station.

[0063] Further, the achievable rate R of the target user after embedding in Scenario 1 I,F is expressed as follows:

[0064] where represents the communication situation of the target user after embedding in Scenario 1 as and when the achievable rate; Indicates that the communication situation of the target user after embedding in Scenario 1 is The achievable rate when; Indicates that the communication situation of the target user after embedding in Scenario 1 is c = 0, The achievable rate when; Is the channel state information of the target user; Is the channel state information of the i-th idle licensed user; Is the power of the target user; P is the power of the licensed user; Set the threshold Is the channel state information of the licensed user with the minimum channel gain; Intermediate variable R B Is the target rate of the licensed user.

[0065] Furthermore, the outage probability of the target user in Scenario I The expression is as follows:

[0066]

[0067] Among them, the intermediate variables A, B, and C are respectively Intermediate variable R F Is the target rate of the target user, η B Is ν B The ratio of ν F Is ν F Is The ratio of.

[0068] Figure 4a And Figure 4b Is the simulation diagram of the design method of the present invention in Scenario 1 (the outage probability simulation diagram of the license-free user under different methods: Figure 4a Corresponding to Figure 4b Corresponding to The specific implementation process is as follows: The license-free user is a delay-tolerant, high-rate demand user. For the license-free user that conforms to the EADS protocol, in order to meet its own rate requirements and not cause performance degradation to the active licensed user, it is necessary to split the rate of the license-free user and then access.

[0069] Before communicating in each resource block, the BS sends the interference threshold of all spectrum holes to the license-free user. The access conditions that are met are expressed as follows: Where Is the channel coefficient of the hole licensed user Of Is the embedded license-free user Of the channel coefficient. Assuming that the power of all licensed users is P and the power of all license-free users is

[0070] Since the users sharing the spectrum use NOMA technology for superimposed transmission and eliminate interference through successive interference cancellation, it can be analyzed that the unlicensed users meeting the embedding conditions will not bring additional interference to other active licensed users in the same spectrum. Unlicensed users and active licensed users 's decoding order can be flexibly adjusted by applying successive interference cancellation according to the relationship between and R0, where is the channel coefficient of the active licensed user . Assume that the target rates of all licensed users are equal, all being R B .

[0071] First, define a threshold c, which is a function of the channel coefficient of the active licensed user . When the hole-licensed user is in its active state, to ensure 's normal decoding, according to the target rate R of B , there is So there is When the unlicensed user meets the condition: , to ensure the high-rate requirements of the unlicensed user itself, the communication message of the unlicensed user needs to be split into 2 data streams. Specifically, split the signal of the unlicensed user into and Therefore, the signal received at the base station within the frequency band can be expressed as: where is the transmission signal of , ω is the Gaussian white noise at the base station, following zero mean and unit variance. α is the power allocation factor, satisfying the formula: 0 ≤ α ≤ 1.

[0072] Assume that all signals {s1, s0, s 01 , s 02} are independently encoded using Gaussian codebooks, and each signal has unit power in expectation. The model in the above formula is also called RSMA. According to the RSMA principle, by adopting the successive interference cancellation decoding order s 01 →s1→s 02 at the BS side, the advantages of RSMA can be achieved. Therefore, the SINRs of decoding signals s 01 , s1, s 02 at the BS side can be respectively expressed as: Therefore, the achievable rate of the licensed user is expressed as: Unauthorized users The achievable rate is expressed as:

[0073]

[0074] Next, to facilitate the analysis of the decoding order between unauthorized users with high-rate requirements and existing active authorized users, the defined threshold c is used, which is a function of the channel gain of the hole authorized users of where According to the original and decoding order, it can be analyzed in two cases:

[0075] ① The original decoding order is To ensure normal decoding, the relationship between and c is: Therefore, the relationship with the threshold also has: c > 0. So, to maximize the achievable rate of the accessed unauthorized users, the decoding order of the accessed unauthorized users and the active authorized users is: Therefore, the rate splitting can set α = 0, s 02 = s0, that is, the unauthorized users do not need to split the transmission. Therefore, the achievable rate of the embedded unauthorized users is:

[0076] ② The original decoding order is: To ensure correct decoding, the relationship between

[0077] 1) c > 0; Given the relationship between the embedded unauthorized users and is: Therefore, for the relationship with c, there are the following two discussions:

[0078] A. c > 0: In this scenario and the decoding order is the same as in ①. The achievable rate of the embedded unauthorized users is expressed as:

[0079] B. c > 0: In this scenario, in order not to affect The QoS performance, while meeting the high-rate requirements of the unlicensed user itself, the unlicensed user needs rate splitting. To maximize the achievable rate, thus it is necessary to satisfy the constraint: γ 02 ≤ c, and the optimal power allocation factor can be calculated when γ 02 = c. To ensure is not affected, the decoding order of the unlicensed user after splitting is: s 01 → s1 → s 02 . After splitting, the rates of s 01 and s 02 can be calculated as follows:

[0080] Therefore, the achievable rate of the embedded unlicensed user is: Therefore, in this scenario, only rate splitting can guarantee the QoS requirements of both licensed and unlicensed users. Otherwise, the unlicensed user cannot access and remains silent.

[0081] 2) c = 0: Since c = 0. Since the transmission of always experiences outages, therefore, to effectively utilize the transmit power, 02 no power part is allocated to transmit s . To maximize 01 the achievable rate of c = 0, the power allocation is set to α = 1, that is, s

[0082] In summary, based on the above discussion, in Scenario 1, the achievable rate of the embedded unlicensed user is expressed as follows:

[0083] Analysis of the outage probability of the unlicensed user in Scenario 1: In Scenario 1, the outage probability of the unlicensed user can be expressed by the following formula:

[0084]

[0085] Where

[0086]

[0087] It can be seen that and in the case of

[0088] Therefore, in Scenario 1, the closed - form expression of the outage probability of the license - free user is derived as follows:

[0089]

[0090] Furthermore, in Scenario 2, the achievable rate \(R\) of the targeted user after embedding is II,F expressed as follows:

[0091]

[0092] where, represents the communication situation of the targeted user after embedding in Scenario 2 as and when the achievable rate; represents the communication situation of the targeted user after embedding in Scenario 2 as when the achievable rate; represents the communication situation of the targeted user after embedding in Scenario 2 as when \(c = 0\) the achievable rate; is the channel state information of the targeted user; is the channel state information of the \(i\) - th idle licensed user; is the power of the targeted user; \(P\) is the power of the licensed user; set the threshold is the channel state information of the licensed user with the minimum channel gain; intermediate variable \(R\) B is the target rate of the licensed user.

[0093] Furthermore, the outage probability of the targeted user in Scenario 2 is expressed as follows:

[0094]

[0095] where, intermediate variable intermediate variable intermediate variable intermediate variable \(R\) F is the target rate of the targeted user, \(\eta\) B is the ratio of \(\nu\) B to \(P\), \(\eta\) F is the ratio of \(\nu\) F is the ratio of.

[0096] Figure 5a and Figure 5b are the simulation diagrams of the design method of the present invention in Scenario 2 (the outage probability simulation diagrams of license - free users under different methods: Figure 5a corresponding to Figure 5b Corresponding to The specific implementation process is as follows: The unlicensed user is a user with sensitive delay and low rate requirements. The channel gain is usually smaller than that of a single licensed user in a hole and can be directly embedded.

[0097] The embedding condition is expressed as: To analyze that embedding unlicensed users will not cause additional interference to licensed users, according to and decoding order, the following two cases are discussed.

[0098] ① The original decoding order is In this scenario, to ensure correct decoding, The relationship with the threshold c is: And c > 0. Since the relationship between the embedded unlicensed user and the licensed user in the hole is: Therefore, The relationship with the threshold c is: c > 0. So, to maximize the achievable rate of the embedded unlicensed user, the decoding order of the embedded unlicensed user and the active licensed user is: Therefore, the achievable rate of the embedded unlicensed user can be expressed as: Note: In this scenario, The minimum interference threshold to be satisfied is Not c.

[0099] ② The original decoding order is To ensure correct decoding in this case of, The relationship with c is:

[0100] 1) c > 0; Since the embedding criterion is: Therefore, for the relationship with c, the following two cases need to be discussed:

[0101] A. c > 0: In this scenario and the decoding order is the same as in ①. However, the threshold conditions to be satisfied are different from those in ①. The interference threshold c needs to be satisfied. Therefore, the achievable rate of the embedded unlicensed user is expressed as:

[0102] B. c > 0; If transmits the signal at full power, the decoding order can only be Therefore, the achievable rate of the embedded unlicensed user is: In order to pursue a higher data rate, we apply the idea of dynamic power control and change the power of the unlicensed user to such that 0 < β < 1, then the signal of the unlicensed user can still be decoded in the second phase, and the achievable rate of the unlicensed user becomes: Therefore, generally speaking, when ...

[0103] 2) c = 0: Since the embedding condition is: When c = 0, because the transmission of... always experiences an outage, so it can only be decoded in the last phase. Therefore, the achievable rate of... is expressed as: c = 0.

[0104] In summary, based on the above discussion, under the proposed EADS protocol in Scenario 2, the achievable rate of the embedded unlicensed user is expressed as follows:

[0105] In Scenario 2, the outage probability of the unlicensed user can be expressed by the following formula:

[0106]

[0107] Where

[0108]

[0109] After derivation, the present invention has calculated the closed - form expression of the outage probability of the unlicensed user in Scenario 2, as follows:

[0110]

[0111] Figure 6a and Figure 6b Compare the proposed EADS - semi - unlicensed scheme with the existing schemes and examine its impact on the outage performance of active licensed users under different transmit power settings. We assume in Figure 6a and assume in In Figure 6b and assume in It can be seen that the proposed scheme has the least impact on the outage probability of active licensed users. This is mainly because the proposed scheme adopts an embedded access method, avoiding additional interference to active licensed users. In contrast, the existing schemes superimpose unlicensed users on orthogonal licensed users within a given threshold range, inevitably introducing additional interference to licensed users.

[0112] Figure 7a and Figure 7b shows the simulation diagrams of the relationship between the system sum rate and the SNR of the unlicensed users in two scenarios, Scenario 1 and Scenario 2. It can be seen that the proposed scheme is significantly superior to the existing MDR-semi-unlicensed and OL-semi-unlicensed schemes in terms of the system sum rate. This improvement can be attributed to three main factors: on the one hand, the proposed protocol adopts an embedded access method to ensure that the embedded unlicensed users do not introduce additional interference to the active licensed users. On the other hand, based on the EADS protocol, the unlicensed users select the licensed spectrum with the minimum MI, thus reducing the multi-user interference (MUI) between users on the same subband. In addition, in Scenario 1, since the unlicensed users access after the RS and utilize RSMA, a greater rate can be achieved compared with the case without RS.

[0113] Embodiment 2

[0114] This embodiment provides a semi-unlicensed transmission system assisted by on-demand rate splitting, as Figure 8 shown, including: a base station and a user terminal, which are used to execute the above-mentioned semi-unlicensed transmission method assisted by on-demand rate splitting.

[0115] Based on the above analysis, the specific implementation of the system sum rate analysis is as follows:

[0116] In Scenario 1, applying the composite successive interference cancellation decoding, the achievable rate of the users under a single frequency band is expressed as follows:

[0117]

[0118] In Scenario 2, the unlicensed users are selected according to the EADS protocol, that is, the unlicensed users with the minimum mutual interference among the active users in the GB subband are selected for access, and the mutual interference value between the unlicensed users and the active licensed users in a single frequency band is expressed as: Therefore, the selection principle of the unlicensed users is the minimum mutual interference with the active licensed users in the same frequency band, which is expressed as follows: Among them, represents the j-th unlicensed user and the i-th active licensed user in the subband The mutual interference value between them, B is the policy set for selecting N F unlicensed users from M. And is the best unlicensed user selection policy after algorithm decision.

[0119] Since there may be multiple authorized users and multiple unauthorized users in the shared GB band, the MUI algorithm adopts a composite serial interference cancellation decoding algorithm. Its decoding idea is to give priority to decoding authorized users based on QoS-Based serial interference cancellation. The last remaining authorized user and the unauthorized users are embedded together to use Hybrid serial interference cancellation, as Figure 3 shown.

[0120] Therefore, in scenario 2, the sum rate within a single band is expressed as follows:

[0121]

[0122] It is easy for those skilled in the art to understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention. What the present invention studies is how to select 1 optimal unauthorized user (target user) in each authorized spectrum to access the authorized spectrum for semi-unauthorized transmission. However, it is not limited to protection. According to the protocol and transmission scheme proposed by the present invention, multiple target unauthorized users can be selected for each band.

Claims

1. A semi-persistent grant-free transmission method assisted by rate splitting on demand, characterized in that Including: S1: The base station broadcasts a preamble; S2: Authorized users and unauthorized users estimate their own channel state information using the preamble; And the authorized users feedback their own communication state information to the base station, including: their own transmit power, channel state information, and spectrum state; S3: The base station selects the communication state information of the authorized users with an idle spectrum state from the received communication state information to calculate the interference gain of each idle authorized user, and broadcasts it as a dynamic interference threshold to all unauthorized users; S4: The base station selects an optimal unauthorized user for each spectrum as the target user under the corresponding spectrum according to the relationship between the interference gain of all unauthorized users and the interference threshold; S5: Perform rate splitting on the target users of each spectrum as needed for data transmission with the base station; S6: After the base station receives the data transmissions from all users, it decodes the first several authorized users sorted from large to small in terms of target rate using the serial interference cancellation decoding method based on channel state information until there is one remaining undecoded authorized user; then it decodes the last undecoded authorized user and all unauthorized users using the hybrid serial interference cancellation decoding scheme.

2. The on-demand rate splitting assisted semi-persistent grant transmission method according to claim 1, wherein S4 includes: comparing the interference gain of the unlicensed user itself with the interference threshold in each spectrum, and calculating the mutual interference between the channel vectors of the unlicensed users below any of the interference thresholds and the channel vectors of the licensed users in each occupied state respectively; taking the unlicensed user corresponding to the minimum mutual interference calculation result as the target user under the corresponding spectrum.

3. The method for grant-free transmission assisted by on-demand rate splitting according to claim 2, wherein Comparing the interference gain of each of the license-free users with the interference threshold includes: using to calculate the interference threshold corresponding to i idle licensed users, and using the formula to calculate the self-interference gain of the jth license-free user; then comparing and ; where P is the transmit power of the licensed user, is the transmit power of the license-free user, is the channel state information of the ith idle licensed user, is the channel state information of the jth license-free user; |.| represents the modulus.

4. The semi-persistent scheduling transmission method assisted by on-demand rate splitting according to claim 2, wherein The channel vectors of the unlicensed users below the interference threshold and the channel vectors of the licensed users in each occupancy state are respectively subjected to mutual interference calculation, including: using to calculate the mutual interference calculation result of the channel vector of the j-th unlicensed user below the interference threshold and the channel vector of the i-th licensed user in the occupancy state ; Identify the j-th unlicensed user below the interference threshold, T i BA The i-th licensed user in the occupancy state, MI denotes mutual interference calculation, and |.| denotes modulus.

5. The semi-persistent grant-free transmission method assisted by on-demand rate splitting according to claim 1, wherein The S5 includes: When the target rate of the target user is greater than the target rate of the authorized user, it is regarded as in Scenario 1, and in Scenario 1, rate splitting is first performed and then data transmission is carried out with the base station; when the target rate of the target user is lower than the target rate of the authorized user, it is regarded as in Scenario 2, and in Scenario 2, direct data transmission is carried out with the base station.

6. The semi-persistent scheduling assisted by rate splitting on demand according to claim 5, wherein The achievable rate R of the target user after embedding in the scenario 1 I,F is expressed as follows: Among them, represents the communication situation of the target user after embedding in the scenario 1 as and the achievable rate when; represents the communication situation of the target user after embedding in the scenario 1 as the achievable rate when; represents the communication situation of the target user after embedding in the scenario 1 as c = 0, the achievable rate when; is the channel state information of the target user; is the channel state information of the i-th idle authorized user; is the power of the target user; P is the power of the authorized user; set the threshold is the channel state information of the authorized user with the minimum channel gain; intermediate variable ν B = 2 RB -1, R B is the target rate of the authorized user.

7. The method for grant-free transmission assisted by on-demand rate splitting according to claim 6, characterized in that The interruption probability of the target user under the scenario I The expression is as follows: Among them, the intermediate variables A, B, and C are respectively Intermediate variable R F is the target rate of the target user, η B is the ratio of ν B to P, η F is the ratio of ν F is the ratio of.

8. The semi-persistent scheduling assisted by on-demand rate splitting according to claim 5, wherein The achievable rate R of the target user after embedding in the scenario 2 II,F is expressed as follows: Among them, represents the communication situation of the target user after embedding under the said scenario 2 as and the achievable rate when; represents the communication situation of the target user after embedding under the said scenario 2 as the achievable rate when; represents the communication situation of the target user after embedding under the said scenario 2 as the achievable rate when; is the channel state information of the target user; is the channel state information of the i-th idle licensed user; is the power of the target user; P is the power of the licensed user; set the threshold is the channel state information of the licensed user with the minimum channel gain; intermediate variable R B is the target rate of the licensed user.

9. The rate-splitting-aided semi-persistent scheduling transmission method according to claim 8, wherein The interruption probability of the target user in Scenario 2 The expression is as follows: Among them, the intermediate variable intermediate variable intermediate variable intermediate variable R F is the target rate of the target user, η B is ν B the ratio of ν F is ν F is the ratio of...

10. A semi-persistent grant-free transmission system assisted by rate splitting on demand, characterized in that Including: A base station and a user terminal for performing the semi-unlicensed transmission method assisted by on-demand rate splitting according to any one of claims 1-9.

Images