User scheduling method for multiple intelligent reflection surface auxiliary communication systems

Abstract

The invention discloses a user scheduling method for multiple intelligent reflection surface auxiliary communication systems, which aims at the multiple intelligent reflection surface auxiliary communication systems composed of a base station, n IRSs and m users and is determined from three aspects of system capacity priority, user transmission frequency fairness and user transmission capacity fairness. According to the method, users in the system can be reasonably scheduled according to actual needs, and proper users are selected for transmission, so that the system meets different communication requirements of capacity maximization, user fairness and the like.

Description

Technical Field

[0001] The invention relates to a user selection method for a multi-intelligent reflective surface cooperative transmission system, which is characterized in selecting a suitable user for transmission according to the transmission characteristics of the multi-intelligent reflective surfaces. Background Art

[0002] Intelligent Reflecting Surface (IRS) has become one of the key technologies of 6G due to its low cost, high energy efficiency and intelligent control of wireless propagation environment. IRS adjusts the phase and amplitude of the incident signal through a controller (such as a programmable gate array), has the characteristic of reconfiguring the wireless propagation environment, and opens up a new degree of freedom for improving the performance of the communication system. IRS technology includes passive IRS and active IRS. Passive IRS can change the signal phase and enhance the received signal strength, but is limited by the multiplicative fading effect, making it impossible for the system to achieve the expected gain. Active IRS expands the function based on passive IRS, which can adjust the signal phase and amplify the signal to normal strength. Collaborative transmission of multiple intelligent reflecting surfaces makes it possible to achieve longer distance transmission with lower power consumption. The present invention designs a user selection method for a multi-intelligent reflecting surface collaborative transmission system. According to the transmission characteristics of multiple intelligent reflecting surfaces, suitable users are selected for transmission, which can realize user scheduling under different system requirements. Summary of the invention

[0003] The purpose of the present invention is to improve the performance and fairness of wireless communication systems. The technical problem to be solved by the present invention is: how to reasonably schedule users and select appropriate users for transmission in a multi-intelligent reflective surface assisted transmission system. Compared with the traditional random selection method, this method can achieve better system performance or better user fairness.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] The multiple intelligent reflective surface assisted communication system is a wireless communication system consisting of a base station, n IRSs and m users. The n IRSs are deployed at different locations between the base station and the user. The base station and the user are both single-antenna devices. When non-adjacent base stations and users cannot communicate directly due to distance or obstacles, the base station signal needs to be transmitted to the user through a multiple intelligent reflective surface cooperative transmission method. The n IRSs are named IRS1 to IRS1 in the order of transmission. n , on which there are L1, L2, ..., L n A reflective unit.

[0006] represents the equivalent channel from the base station to user j, where represents the channel from the base station to the l1th reflection unit on IRS1, IRS n Previous n Channels from reflection units to users, l1 to l n They all represent the corresponding cumulative variables.

[0007] A user scheduling method for a multiple intelligent reflective surface assisted communication system based on system capacity priority is implemented by the following steps:

[0008] Step 1: performing channel estimation between two adjacent nodes, wherein the two adjacent nodes refer to between a base station and a nearest IRS, between adjacent IRSs, and between a user and a nearest IRS;

[0009] Step 2: The controller selects the transmission user based on the channel state information determined in step 1 and based on the system capacity. Since the user capacity is positively correlated with the user equivalent channel, Select the transmission user, where argmax means that the function The value of the independent variable j when it reaches the maximum value;

[0010] Step 3: Adjust the phase of the reflection unit on each IRS so that the equivalent channel satisfies the form of step 2.

[0011] Step 4: The base station and the selected user j * Start the transfer;

[0012] Step 5: The base station and the selected user j * When the transmission is finished or the channel in the system changes, reselect the user according to the above steps.

[0013] The user scheduling method of multiple intelligent reflective surface assisted communication systems based on fairness of user transmission times is implemented by the following steps:

[0014] Step 1: Initialize the non-transmitting user set S = {1, 2, ..., m};

[0015] Step 2: performing channel estimation between two adjacent nodes, wherein the two adjacent nodes refer to between a base station and a nearest IRS, between adjacent IRSs, and between a user and a nearest IRS;

[0016] Step 3: The controller selects a transmission user based on the fairness of the number of user transmissions according to the channel state information determined in step 1, thereby selecting a suitable transmission user from the set of non-transmitting users S, that is, based on Select the transmission user, where argmax represents the value of the independent variable when the function takes the maximum value;

[0017] Step 4: Adjust the phase of the reflection unit on each IRS so that the equivalent channel satisfies the form of step 3;

[0018] Step 5: Remove the selected user j from the set S * , update the set S = S / {j *}, if the updated S is an empty set, reset the set S = {1,2,...,m}, and then the base station and the selected user j * Start the transfer;

[0019] Step 6: The base station and the selected user j * When the transmission is finished or the channel in the system changes, reselect the user according to the above steps.

[0020] The user scheduling method of multiple intelligent reflecting surface assisted communication system based on user transmission capacity fairness is implemented by the following steps:

[0021] Step 1: Initialize the user's cumulative transmission capacity c1=c2=...=c m =0, the fairness factor τ is determined according to demand, where τ represents the transmission capacity difference when fairness needs to be considered;

[0022] Step 2: performing channel estimation between two adjacent nodes, wherein the two adjacent nodes refer to between a base station and a nearest IRS, between adjacent IRSs, and between a user and a nearest IRS;

[0023] Step 3: The controller selects a suitable user according to the channel state information determined in step 1.

[0024] if based on Select the transmission user, where argmax represents the value of the independent variable when the function takes the maximum value;

[0025] if and When there is a result, based on Select the transfer user;

[0026] if and When there are multiple results, based on Select the user;

[0027] Step 4: Adjust the phase of the reflection unit on each IRS so that the equivalent channel satisfies the form of step 3;

[0028] Step 5: Update the cumulative transmission capacity of user j* Where P represents the base station transmission power, represents the receiver noise power at the j*th user, the base station and the selected user j *Start the transfer;

[0029] Step 6: The base station and the selected user j * When the transmission is finished or the channel in the system changes, reselect the user according to the above steps.

[0030] Compared with the prior art, the present invention fully selects appropriate users for transmission according to the system maximization performance requirement or the user fairness requirement, thereby achieving better system performance or better user fairness. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of the intelligent reflective surface assisted communication system of the present invention.

[0032] Figure 2 This is a schematic diagram of the process of Example 1 of the present invention.

[0033] Figure 3 This is a schematic diagram of the process of Example 2 of the present invention.

[0034] Figure 4 This is a schematic diagram of the process of Example 3 of the present invention.

[0035] Figure 5 The figure shows the system capacity comparison between the embodiments 1, 2, 3 and the random selection scheme of the present invention.

[0036] Figure 6 It is the ratio of service times of different users in embodiments 1, 2, 3 and the random selection scheme of the present invention.

[0037] Figure 7 It is the ratio of the total transmission capacity of different user services in embodiments 1, 2, 3 of the present invention and the random selection scheme. DETAILED DESCRIPTION

[0038] The invention is further described below with reference to the accompanying drawings and specific embodiments.

[0039] like Figure 1 As shown in FIG. 1 , a multiple intelligent reflective surface assisted communication system is a wireless communication system composed of a base station (BS), n IRSs and m users. The IRSs are deployed at different positions between the base station and the user. Both the base station and the user are single-antenna devices. When non-adjacent base stations and users cannot communicate directly due to distance or obstacles, a multiple intelligent reflective surface cooperative transmission method is required to transmit the base station signal to the user. The n IRSs are named IRS1 to IRS2 in the order of transmission. n , on which there are L1, L2, ..., L n A reflective unit.

[0040] Assuming that the channels between different IRSs are stable and the influence of small-scale fading amplitude is ignored, and the channel phases between the reflection units of adjacent IRSs are the same, after using IRS to offset the phases of the channels on both sides, it can be used represents the equivalent channel from the base station to user j, where represents the channel from the base station to the l1th reflection unit on IRS1, IRS n Previous n Channels from reflection units to users, l1 to l n They all represent corresponding cumulative variables, such as l1 represents a positive integer between 1 and L1, l n Indicates 1 to L n The following is a positive integer between . The user scheduling method is determined from three perspectives: system capacity priority, user transmission number fairness, and user transmission capacity fairness.

[0041] Example 1

[0042] like Figure 2 As shown, the user scheduling method of multiple intelligent reflective surface assisted communication systems based on system capacity priority is implemented by the following steps:

[0043] Step 1: performing channel estimation between two adjacent nodes, wherein the two adjacent nodes refer to between a base station and a nearest IRS, between adjacent IRSs, and between a user and a nearest IRS;

[0044] Step 2: The controller selects the transmission user based on the channel state information determined in step 1 and based on the system capacity. Since the user capacity is positively correlated with the user equivalent channel, Select the transmission user, where argmax means that the function The value of the independent variable j when it reaches the maximum value;

[0045] Step 3: Adjust the phase of the reflection unit on each IRS so that the equivalent channel satisfies the form of step 2.

[0046] Step 4: The base station and the selected user j * Start the transfer;

[0047] Step 5: The base station and the selected user j * When the transmission is finished or the channel in the system changes, reselect the user according to steps 1 to 4.

[0048] As an implementation method, the phase adjustment method of the reflector units on the m IRSs in step 3 is as follows: the phase of the l1th reflector unit on the first IRS is Where arg represents the argument of the complex number, -θ (k)-(k+1)It represents the phase of the channel between any reflection unit on the kth IRS and any reflection unit on the k+1th IRS. The phase of the reflection unit on the i-th (i=2,…,n-1)th IRS is -θ (i)-(i+1) , the nth IRS on the lth n The phase adjustment of each reflector unit is

[0049] Example 2

[0050] like Figure 3 As shown, the user scheduling method of multiple intelligent reflective surface assisted communication systems based on fairness of user transmission times is implemented by the following steps:

[0051] Step 1: Initialize the non-transmitting user set S = {1, 2, ..., m};

[0052] Step 2: performing channel estimation between two adjacent nodes, wherein the two adjacent nodes refer to between a base station and a nearest IRS, between adjacent IRSs, and between a user and a nearest IRS;

[0053] Step 3: The controller selects a transmission user based on the fairness of the number of user transmissions according to the channel state information determined in step 1, thereby selecting a suitable transmission user from the set of non-transmitting users S, that is, based on Select the transmission user, where argmax represents the value of the independent variable when the function takes the maximum value;

[0054] Step 4: Adjust the phase of the reflection unit on each IRS so that the equivalent channel satisfies the form of step 3;

[0055] Step 5: Remove the selected user j from the set S * , update the set S = S / {j *}, if the updated S is an empty set, it means that all current users have been served, then reset the set S = {1,2,...,m}, and then the base station and the selected user j * Start the transfer;

[0056] Step 6: The base station and the selected user j * When the transmission is finished or the channel in the system changes, reselect the user according to steps 1 to 5.

[0057] Example 3

[0058] like Figure 4 As shown, the user scheduling method of multiple intelligent reflective surface assisted communication system based on user transmission capacity fairness is implemented by the following steps:

[0059] Step 1: Initialize the user's cumulative transmission capacity c1=c2=...=c m=0, the fairness factor τ is determined according to demand, where τ represents the transmission capacity difference when fairness needs to be considered;

[0060] Step 2: performing channel estimation between two adjacent nodes, wherein the two adjacent nodes refer to between a base station and a nearest IRS, between adjacent IRSs, and between a user and a nearest IRS;

[0061] Step 3: The controller selects a suitable user based on the channel state information determined in step 1. This means that the difference in the cumulative transmission capacity between the current users is not less than the fairness factor and is in the fair transmission range. Select the transmission user, where argmax represents the value of the independent variable when the function takes the maximum value; if This means that the difference in the cumulative transmission capacity between users exceeds the fairness factor. The transmission capacity of some users is too low, which causes unfairness. Therefore, users with smaller cumulative transmission capacity need to be compensated. Select Transfer User, when When there are multiple results, select the user with the larger capacity in the current state, that is, based on Select Users.

[0062] Step 4: Adjust the phase of the reflection unit on each IRS so that the equivalent channel satisfies the form of step 3;

[0063] Step 5: Update the cumulative transmission capacity of user j* Where P represents the base station transmission power, represents the receiver noise power at the j*th user, the base station and the selected user j * Start the transfer;

[0064] Step 6: The base station and the selected user j * When the transmission is finished or the channel in the system changes, reselect the user according to steps 1 to 5.

[0065] Figure 5 , Figure 6 and Figure 7 The performance differences between the above three methods and the random user selection method are compared respectively. There are three users in the comparison system, user 1 has the best channel condition, user 2 has the second best channel condition, and user 3 has the worst channel condition.

[0066] Figure 5 A comparison chart of the total system capacity obtained by using Matlab for the three user selection methods involved in this patent and the random user selection method is given. It can be seen that the user selection algorithm based on system capacity priority can achieve a better total system capacity, but combined with Figure 6 , 7It can be seen that its user fairness is slightly worse; the total system capacity corresponding to the fairness based on user transmission times, the fairness based on user transmission capacity and the random user selection method is relatively close.

[0067] Figure 6 A comparison chart of the user service times obtained by using Matlab for the three user selection methods involved in this patent and the random user selection method is given. It can be seen that the user selection algorithm based on the fairness of user transmission times can achieve the average proportion of user service times, and the effect is close to that of the random user selection method, but combined with Figure 5 It can be seen that the performance of the user selection algorithm based on the fairness of user transmission times is slightly better than the random user selection method.

[0068] Figure 7 A comparison chart of the capacity of each user obtained by using Matlab for the three user selection methods involved in this patent and the random user selection method is given. It can be seen that the user selection algorithm based on the fairness of user transmission capacity can achieve the averaging of the capacity of each user.

Claims

1. A user scheduling method for a communication system assisted by multiple intelligent reflective surfaces, characterized in that: The multiple intelligent reflective surface assisted communication system is a wireless communication system consisting of a base station, n IRSs and m users. The n IRSs are deployed at different locations between the base station and the user. Both the base station and the user are single-antenna devices. The base station signal is transmitted to the user through a multiple intelligent reflective surface cooperative transmission method between non-adjacent base stations and users. The n IRSs are named IRS1 to IRS1 according to the transmission order. n , on which there are L1, L2, ..., L n Reflection unit; represents the equivalent channel from the base station to user j, where represents the channel from the base station to the l1th reflection unit on IRS1, IRS n Previous n Channels from reflection units to users, l1 to l n All represent corresponding cumulative variables; A user scheduling method for a multiple intelligent reflective surface assisted communication system based on system capacity priority is implemented by the following steps: Step 1: performing channel estimation between two adjacent nodes, wherein the two adjacent nodes refer to between a base station and a nearest IRS, between adjacent IRSs, and between a user and a nearest IRS; Step 2: The controller selects the transmission user based on the channel state information determined in step 1 and based on the system capacity. Since the user capacity is positively correlated with the user equivalent channel, Select the transmission user, where argmax means that the function The value of the independent variable j when it reaches the maximum value; Step 3: Adjust the phase of the reflection unit on each IRS so that the equivalent channel satisfies the form of step 2. Step 4: The base station and the selected user j * Start the transfer; Step 5: The base station and the selected user j * When the transmission is finished or the channel in the system changes, reselect the user according to the above steps.

2. A user scheduling method for a communication system assisted by multiple intelligent reflective surfaces, characterized in that: The multiple intelligent reflective surface assisted communication system is a wireless communication system consisting of a base station, n IRSs and m users. The n IRSs are deployed at different locations between the base station and the user. Both the base station and the user are single-antenna devices. The base station signal is transmitted to the user through a multiple intelligent reflective surface cooperative transmission method between non-adjacent base stations and users. The n IRSs are named IRS1 to IRS1 according to the transmission order. n , on which there are L1, L2, ..., L n Reflection unit; represents the equivalent channel from the base station to user j, where represents the channel from the base station to the l1th reflection unit on IRS1, IRS n Previous n Channels from reflection units to users, l1 to l n All represent corresponding cumulative variables; The user scheduling method of multiple intelligent reflective surface assisted communication systems based on fairness of user transmission times is implemented by the following steps: Step 1: Initialize the non-transmitting user set S = {1, 2, ..., m}; Step 2: performing channel estimation between two adjacent nodes, wherein the two adjacent nodes refer to between a base station and a nearest IRS, between adjacent IRSs, and between a user and a nearest IRS; Step 3: The controller selects a transmission user based on the fairness of the number of user transmissions according to the channel state information determined in step 1, thereby selecting a suitable transmission user from the set of non-transmitting users S, that is, based on Select the transmission user, where argmax represents the value of the independent variable when the function takes the maximum value; Step 4: Adjust the phase of the reflection unit on each IRS so that the equivalent channel satisfies the form of step 3; Step 5: Remove the selected user j* from the set S and update the set S = S / {j * }, if the updated S is an empty set, it means that all current users have been served, then reset the set S = {1,2,...,m}, and then the base station and the selected user j * Start the transfer; Step 6: The base station and the selected user j * When the transmission is finished or the channel in the system changes, reselect the user according to the above steps.

3. A user scheduling method for a communication system assisted by multiple intelligent reflective surfaces, characterized in that: The multiple intelligent reflective surface assisted communication system is a wireless communication system consisting of a base station, n IRSs and m users. The n IRSs are deployed at different locations between the base station and the user. Both the base station and the user are single-antenna devices. The base station signal is transmitted to the user through a multiple intelligent reflective surface cooperative transmission method between non-adjacent base stations and users. The n IRSs are named IRS1 to IRS1 according to the transmission order. n , on which there are L1, L2, ..., L n Reflection unit; represents the equivalent channel from the base station to user j, where represents the channel from the base station to the l1th reflection unit on IRS1, IRS n Previous n Channels from reflection units to users, l1 to l n All represent corresponding cumulative variables; The user scheduling method of multiple intelligent reflecting surface assisted communication system based on user transmission capacity fairness is implemented by the following steps: Step 1: Initialize the user's cumulative transmission capacity c1=c2=...=c m =0, the fairness factor τ is determined according to demand, where τ represents the transmission capacity difference when fairness needs to be considered; Step 2: performing channel estimation between two adjacent nodes, wherein the two adjacent nodes refer to between a base station and a nearest IRS, between adjacent IRSs, and between a user and a nearest IRS; Step 3: The controller selects a suitable user according to the channel state information determined in step 1. if based on Select the transmission user, where argmax represents the value of the independent variable when the function takes the maximum value; if and When there is a result, based on Select the transfer user; if and When there are multiple results, based on Select the user; Step 4: Adjust the phase of the reflection unit on each IRS so that the equivalent channel satisfies the form of step 3; Step 5: Update the cumulative transmission capacity of user j* Where P represents the base station transmission power, represents the receiver noise power at the j*th user, the base station and the selected user j * Start the transfer; Step 6: The base station and the selected user j * When the transmission is finished or the channel in the system changes, reselect the user according to the above steps.

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