Low-complexity interference management method under non-orthogonal multiple access mechanism

Abstract

The invention discloses a low-complexity interference management method under a non-orthogonal multiple access mechanism. Only a NOMA cluster interference minimum value set # imgabs0 # and a minimum threshold value # imgabs1 # of the total downlink power of the base station under the activation state of the first N-1 users need to be calculated, and whether the low-complexity interference management method provided by the invention is started or not is judged by matching two parameters calculated by an interference threshold value theta in the NOMA cluster and the total downlink power Pmax of the base station with the two parameters calculated by the NOMA cluster interference minimum value set # imgabs0 # and the minimum threshold value # imgabs1 #. And if the NOMA system is started, the optimal user power distribution value can be directly obtained by calculating the # imgabs2 # so as to meet effective interference control in the NOMA cluster, and the method is a low-complexity interference management scheme suitable for the NOMA system.

Description

Technical Field

[0001] The present invention relates to the technical field of interference management of non-orthogonal multiple access, and in particular to a low-complexity interference management method under a non-orthogonal multiple access mechanism. Background Art

[0002] In wireless networks, intra-cluster interference (ICI) of non-orthogonal multiple access (NOMA) technology is a very important concept. This is because the core concept of NOMA technology is to allow multiple users to perform non-orthogonal transmission on the same spectrum resources to improve spectrum efficiency and system capacity. However, this non-orthogonal transmission method will inevitably lead to mutual interference between users' signals, of which intra-cluster interference is one of the main aspects. First, intra-cluster interference will directly affect the performance of NOMA system. That is, if the intra-cluster interference is too large, it will cause the receiver to face greater difficulties in demodulating user signals, thereby reducing the system's bit error rate performance, throughput and spectrum efficiency. Secondly, in NOMA system, different users may be subject to different degrees of intra-cluster interference due to differences in channel conditions, transmission power and other factors. If the intra-cluster interference is too large and is not effectively managed, it may cause some users to suffer a large performance loss, thus affecting fairness among users. Then, the size and distribution of intra-cluster interference have an important impact on the resource allocation strategy of NOMA system. However, in the scenario of non-orthogonal multiple access technology application, the increase in the number of users on a single subcarrier will lead to a surge in the computational complexity of the interference management method, which affects the timeliness of the algorithm and increases the waste of system computing resources. Since intra-cluster interference is an inherent problem in the NOMA system, how to manage and mitigate intra-cluster interference with low complexity has become an important direction of NOMA technology research. Summary of the invention

[0003] Purpose of the invention: The present invention provides a low-complexity interference management method under a non-orthogonal multiple access mechanism, which dynamically adjusts the user's downlink data transmission power according to the NOMA cluster interference threshold set by the base station, thereby achieving effective management of NOMA cluster interference.

[0004] Technical solution: The low-complexity interference management method under a non-orthogonal multiple access mechanism described in the present invention comprises the following steps:

[0005] Step 1: The base station monitors the channel gain information of N users, the minimum intra-cluster interference threshold θ of the NOMA cluster allowed by the base station, and the total downlink power value p of the base station max , if the channel gain information of a user changes, go to step 2; otherwise, if the minimum threshold value Θ of the NOMA cluster allowed by the base station changes, go to step 3; otherwise, if the total downlink power value p of the base station changes, go to step 3;max When a change occurs, go to step 4;

[0006] Step 2: For the first N-1 users, calculate the lowest NOMA cluster interference value in the activation state of each user. If the interference threshold value θ of the base station is greater than or equal to the maximum value in the set of the lowest NOMA cluster interference values ​​in the user activation state of the first N-1 users, proceed to step 3;

[0007] Step 3: Calculate the minimum threshold value of the base station downlink total power. If the base station downlink total power value is greater than or equal to the minimum threshold value of the base station downlink total power, proceed to step 4.

[0008] Step 4: Based on the channel gains of N users, the minimum intra-cluster interference threshold θ of the NOMA cluster allowed by the base station, and the total downlink power value p of the base station max , calculate the optimal power allocation value of the N users that make up the NOMA cluster.

[0009] Furthermore, in step 1, if the minimum threshold value Θ of the intra-cluster interference of the NOMA cluster allowed by the base station changes, that is, whether the minimum threshold value Θ of the intra-cluster interference of the NOMA cluster allowed by the base station satisfies Θ≥max{I1,I2,…,I n ,…,I N-1}condition.

[0010] Furthermore, in step 1, if the total downlink power value of the base station is p max When the change occurs, the total downlink power value of the base station p max Is it satisfied? condition.

[0011] Furthermore, in step 2, the lowest NOMA cluster interference value in the user activation state of the first N-1 users is calculated in two ways, namely, the calculation method for user 1 is:

[0012] Furthermore, for user n, The calculation method is in, σ 2 is the noise value at the user receiver.

[0013] Furthermore, in step 3, the power value of each user in the NOMA cluster is given: for user 1,

[0014]

[0015] Furthermore, the power value of each user in the NOMA cluster is given: for user n, have

[0016]

[0017] Furthermore, the power value of each user in the NOMA cluster is given: for user N, there is

[0018]

[0019] Furthermore, in step 4, the channel gains {h1,…,h N}, the minimum intra-cluster interference threshold Θ of the NOMA cluster allowed by the base station and the total downlink power value p of the base station max The optimal power allocation value of all users based on NOMA intra-cluster interference management can be directly calculated with low computational complexity.

[0020] Furthermore, if only the total downlink power value of the base station is changed in the network, and If the condition is still satisfied, only the power value of the Nth user needs to be updated, and the power values ​​of the other users remain unchanged.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The present invention provides a low-complexity NOMA intra-cluster interference management method suitable for non-orthogonal multiple access technology, which solves the problem of increased computational complexity of interference management caused by a large number of coexisting users on a single subcarrier in the NOMA system; the base station monitors the channel gain information of N users, the minimum intra-cluster interference threshold value Θ of the NOMA cluster allowed by the base station, and the base station downlink total power value p max , the optimal power value is allocated to each user, thereby completing the effective management of interference within the NOMA cluster, which physically conforms to the scenario of real applications and can be effectively applied in engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0023] like Figure 1 As shown, a low-complexity interference management method under a non-orthogonal multiple access mechanism includes the following steps:

[0024] Step 1: The base station monitors the channel gain information of N users, the minimum intra-cluster interference threshold θ of the NOMA cluster allowed by the base station, and the total downlink power value p of the base station max If the channel gain information of a user changes, go to step 2; otherwise, if the minimum threshold value Θ of the NOMA cluster allowed by the base station changes, go to step 3; otherwise, if the total downlink power value p of the base station changes, go to step 3. max If a change occurs, go to step 4.

[0025] Step 2: For the first N-1 users, calculate the minimum interference value of the NOMA cluster in the activation state of each user. If the interference threshold value Θ of the base station is greater than or equal to the maximum value in the set of the minimum interference values ​​of the NOMA cluster in the user activation state of the first N-1 users, proceed to step 3; otherwise, the method proposed in the present patent is not applicable.

[0026] Step 3: Calculate the minimum threshold value of the base station downlink total power. If the base station downlink total power value is greater than or equal to the minimum threshold value of the base station downlink total power, proceed to step 4; otherwise, the method proposed in the present invention is not applicable.

[0027] Step 4: Based on the channel gains of N users, the minimum intra-cluster interference threshold θ of the NOMA cluster allowed by the base station, and the total downlink power value p of the base station max , calculate the optimal power allocation value of the N users that make up the NOMA cluster.

[0028] In step 1, the low-complexity interference management method is based on the channel gain information of N users, the minimum intra-cluster interference threshold θ of the NOMA cluster allowed by the base station, and the total downlink power value p of the base station. max Different changes in the three parameters go into step 2, step 3 and step 4 respectively.

[0029] The first judgment criterion is whether the channel gain information of N users has changed; the second judgment criterion is whether the minimum threshold value Θ of the NOMA cluster allowed by the base station satisfies Θ≥max{I1,I2,…,I n ,…,I N-1 The third criterion is the total downlink power value p of the base station. max Whether the total downlink power value of the base station is met condition.

[0030] The lowest value of NOMA cluster interference in the user activation state of the first N-1 users is calculated in two ways: the calculation method for user 1 is: And for user n, The calculation method is

[0031] The optimal power allocation value of N users is calculated in three ways, which are as follows for user 1: For user n, The calculation method is And the calculation method for user N is:

[0032] The channel gains of the first N users {h1,…,h N}, the minimum intra-cluster interference threshold Θ of the NOMA cluster allowed by the base station and the total downlink power value p of the base station max The optimal power allocation value of all users based on NOMA intra-cluster interference management can be directly calculated with low computational complexity.

[0033] If only the total downlink power value of the base station is changed in the network, and If the condition is still satisfied, only the power value of the Nth user needs to be updated, and the power values ​​of the other users remain unchanged.

[0034] The base station dynamically adjusts the power values ​​allocated to N users by adjusting the interference threshold value Θ within the NOMA cluster, so that the total interference value within the NOMA cluster does not exceed the threshold value Θ, thus completing the effective management of the interference within the NOMA cluster.

[0035] Next, the design of the present invention is further analyzed and described in detail.

[0036] In the network based on non-orthogonal multiple access technology designed by the solution of the present invention, it is assumed that there are N user terminals in total, and the base station uses non-orthogonal multiple access technology to provide service support for these N user terminals on the same subcarrier. Without loss of generality, it is assumed that the N users are arranged in descending order of the base station to user channel gain, that is, h1>…>h n >…>h N .

[0037] In the non-orthogonal multiple access mechanism, each user terminal will receive the signal superposition sent by the base station to all user information. The received superposition signal can be processed by the serial interference cancellation SIC technology at the receiver. Users with lower channel gain will only receive NOMA cluster interference from users with higher channel gain than theirs, which makes the NOMA cluster interference problem more difficult. Therefore, in a network based on non-orthogonal multiple access, in order to effectively improve the data transmission rate in the network, it is necessary to manage the above-mentioned NOMA cluster interference. However, with the increase in the dimension of the network, computational complexity has now become a standard for measuring the efficiency of an algorithm execution and the computing resources occupied, so how to provide a simple, effective and low-complexity interference management algorithm is the key problem studied and solved by the present invention.

[0038] First, for each user in the NOMA cluster, the lowest interference value of the NOMA cluster in its activated state is calculated:

[0039] For user 1, there is

[0040]

[0041] in, σ 2 is the noise value at the user receiver.

[0042] For user n, have

[0043]

[0044] If the NOMA cluster interference threshold Θ≥max{I1,I2,…,I n ,…,I N-1}, and the total downlink power value of the base station in is the minimum threshold of the total downlink power of the base station, Then the low-complexity interference management method under a non-orthogonal multiple access mechanism proposed in the present invention is applicable.

[0045] Then, the power value of each user in the NOMA cluster is given:

[0046] For user 1, there is

[0047]

[0048] For user n, have

[0049]

[0050] For user N, we have

[0051]

[0052] The base station dynamically adjusts the power values ​​allocated to N users by adjusting the threshold value Θ of the interference within the NOMA cluster, so that the total interference value within the NOMA cluster does not exceed the threshold value Θ, thus completing the management of the interference within the NOMA cluster.

[0053] The present invention only needs to calculate the lowest NOMA cluster interference value set {I n}, and the minimum threshold of the total downlink power of the base station And by comparing the NOMA cluster interference threshold Θ and the base station downlink total power P max The two parameters calculated above are matched to determine whether to start the low-complexity interference management method proposed by the present invention. If started, by calculating p n , The optimal user power allocation value can be directly obtained to meet the effective interference control within the NOMA cluster. It is a low-complexity interference management solution suitable for the NOMA system.

Claims

1. A low-complexity interference management method under a non-orthogonal multiple access mechanism, characterized in that: The steps include: Step 1: The base station monitors the channel gain information of N users, the minimum intra-cluster interference threshold θ of the NOMA cluster allowed by the base station, and the total downlink power value p of the base station max , if the channel gain information of any user changes, go to step 2; Otherwise, if the minimum intra-cluster interference threshold θ of the NOMA cluster allowed by the base station changes, go to step 3; Otherwise, if the total downlink power value of the base station is p max When a change occurs, go to step 4; Step 2: For the first N-1 users, calculate the lowest NOMA cluster interference value in the activation state of each user. If the interference threshold value θ of the base station is greater than or equal to the maximum value in the set of the lowest NOMA cluster interference values ​​in the user activation state of the first N-1 users, proceed to step 3; Step 3: Calculate the minimum threshold value of the base station downlink total power. If the base station downlink total power value is greater than or equal to the minimum threshold value of the base station downlink total power, proceed to step 4. Step 4: Based on the channel gains of N users, the minimum intra-cluster interference threshold θ of the NOMA cluster allowed by the base station, and the total downlink power value p of the base station max , calculate the optimal power allocation value of the N users that make up the NOMA cluster.

2. The low complexity interference management method under the non-orthogonal multiple access mechanism according to claim 1, characterized in that: In step 1, if the minimum threshold value Θ of the NOMA cluster intra-cluster interference allowed by the base station changes, that is, whether the minimum threshold value Θ of the NOMA cluster intra-cluster interference allowed by the base station satisfies Θ≥max{I1,I2,…,I n ,…,I N-1 }condition.

3. The low complexity interference management method under the non-orthogonal multiple access mechanism according to claim 1, characterized in that: In step 1, if the total downlink power value of the base station is p max When the change occurs, the total downlink power value of the base station p max Is it satisfied? condition.

4. The low complexity interference management method under the non-orthogonal multiple access mechanism according to claim 1, characterized in that: In step 2, the minimum interference value of the NOMA cluster in the user activation state of the first N-1 users is calculated in two ways. The calculation method for user 1 is: in, σ 2 is the noise value at the user receiver, h i is the channel gain.

5. The low complexity interference management method under the non-orthogonal multiple access mechanism according to claim 4, characterized in that: For user n, The calculation method is 6. The low complexity interference management method under the non-orthogonal multiple access mechanism according to claim 1, characterized in that: In step 3, the power value of each user in the NOMA cluster is given: for user 1, 7. The low complexity interference management method under the non-orthogonal multiple access mechanism according to claim 1, characterized in that: In step 3, the power value of each user in the NOMA cluster is given: for user n, have 8. The low complexity interference management method under the non-orthogonal multiple access mechanism according to claim 1, characterized in that: In step 3, the power value of each user in the NOMA cluster is given: for user N, 9. The low complexity interference management method under the non-orthogonal multiple access mechanism according to claim 1, characterized in that: In step 4, the channel gains {h1,…,h N }, the minimum intra-cluster interference threshold Θ of the NOMA cluster allowed by the base station and the total downlink power value p of the base station max The optimal power allocation value of all users based on NOMA intra-cluster interference management can be directly calculated with low computational complexity.

10. The low complexity interference management method under the non-orthogonal multiple access mechanism according to claim 9, characterized in that: If only the total downlink power value of the base station is changed in the network, and If the condition is still satisfied, only the power value of the Nth user needs to be updated, and the power values ​​of the other users remain unchanged.

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