[0053] 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.
[0054] image 3 It is the flow chart of the user selection method provided by the present invention, such as image 3 As shown, the method includes:
[0055] Step 301: Store the codebook grouped according to the orthogonality principle on the base station side and the user terminal side respectively.
[0056] Step 302: The user terminal estimates the channel, selects a codebook according to the channel estimation information, and feeds back the channel estimation information and the selected codebook information to the base station.
[0057] In this step, the user terminal calculates the SINR value or CQI value corresponding to each codebook according to the channel estimation information, and selects the codebook corresponding to the maximum SINR value or the maximum CQI value. The quantized value of the modulus square of the channel vector is calculated according to the channel estimation information, and the calculated quantized value and the number (PVI) of the selected codebook are fed back to the base station.
[0058] Step 303: The base station groups the user terminals according to the grouping status of the codebook and the codebook information fed back by the user terminal, selects a user group according to the channel estimation information fed back by the user terminal, and in the selected user group according to each user in the user group The channel estimation information selects the user.
[0059] In this step, the base station takes the user with the largest modulus of the channel vector among the users as the selected first user, and sets the user group where the first user is located as the selected user group, and traverses the selected user For all unselected users in the group, calculate the SINR of each unselected user according to the channel estimation information, select the user with the largest SINR, and return to all unselected users in the selected user group by traversing User steps until a predetermined number of users are selected. The predetermined number is predetermined according to the network planning of the communication system, and generally the predetermined number is equal to the number of antennas of the base station.
[0060] Let’s take the base station multi-antenna user-single-antenna TDD system as an example. image 3 Provide examples for user selection methods.
[0061] Table 1 is a codebook table pre-stored on the user terminal side and the base station side.
[0062]
[0063] Table I
[0064] Figure 4 It is a schematic diagram of the codebook group after grouping the codebooks in Table 1.
[0065] by Figure 4 It can be seen that the 16 codebooks in Table 1 are divided into 4 groups, each with 4 codebook vectors, and the 4 codebook vectors in each codebook group are orthogonal to each other.
[0066] On the user terminal side and the base station side, follow Figure 4 The codebook group of, each codebook group is pre-stored.
[0067] In the communication process between the user terminal and the base station, the user terminal first estimates the downlink channel, selects the codebook based on the estimated downlink channel information, and calculates the modulus of the downlink channel vector modulus (‖h‖) according to the estimated downlink channel information 2 ), the calculated quantized value and the PVI of the selected codebook are fed back to the base station, and then the base station obtains the uplink channel information of all users according to the reciprocity of the uplink and downlink channels and the downlink channel information fed back by the users, Group users according to codebook grouping and PVI feedback from users, and find out ‖h‖ 2 The user with the largest value is the first user selected, and the user group of the first user is the selected user group. In this user group, according to certain optimization criteria, such as the maximum capacity criteria, according to the user The uplink channel information polls a group of optimal users to complete the communication.
[0068] Figure 5 It is a flow chart of a method for user selection in a TDD system with multiple antennas and a single antenna for a base station provided by the present invention. Such as Figure 5 As shown, the method includes:
[0069] Step 501, follow Figure 4 The codebooks shown in Table 1 are grouped, and the grouped codebooks are stored in the user terminal and the base station according to the codebook group.
[0070] Step 502: The user terminal estimates the downlink channel, and calculates the modulus of the channel vector ‖h‖ according to the estimated downlink channel information. 2 And the corresponding SINR value or CQI value of each codebook in the channel state, determine the codebook PVI corresponding to the maximum SINR value or the maximum CQI value, and set ‖h‖ 2 The quantized value of and the determined PVI are fed back to the base station.
[0071] Step 503: The base station obtains the uplink channel vector of each user according to the reciprocity of the uplink and downlink channels and the downlink channel information fed back by the user, and allocates the users to different user groups according to the PVI fed back by the user.
[0072] In this step, users whose codebooks represented by the feedback PVI belong to the same codebook group are allocated to the same user group.
[0073] Step 504, the base station modulates the channel vector modulus ‖h‖ 2 The largest user is selected as the first user, and from the user group where the first user belongs, according to predetermined criteria, such as the maximum capacity criteria, poll other users that need to be selected.
[0074] According to the maximum capacity criterion, the method of polling other users from the user group is the same as figure 1 The methods shown are the same, including:
[0075] Step 1: According to the selected first user k 1 Channel state information h 1 , Using Gram-Schmidt orthogonalization to find the first user k 1 Channel state information h 1 Corresponding set of orthogonal basis W, where W is composed of W(i), i=1...M, M is the number of antennas at the base station, W(1)=h 1 =h 1 /‖H 1 ‖.
[0076] Step 2: Traverse all unselected users in the selected user group, and select a group of users from the selected user group to ensure system performance.
[0077] In this step, the number of users to be selected is M-1, and M is the number of antennas on the base station side.
[0078] Specifically, traverse all unselected users in the selected user group, calculate the signal-to-noise ratio of each user, select the user with the largest signal-to-noise ratio, and then return to the operation of traversing all unselected users , Until M-1 users are selected, the following procedures can be used to select users:
[0079] i=2,...,M
[0080] set SINR max i = 0
[0081] loop
[0082] for j=1,...,J,j∈Θ
[0083] SINR ′ j = | | h j ′ | | 2 ρ ′ j 2 | | h j ′ | | 2 ( 1 - ρ ′ j 2 ) + P / M , ρ′ j =|h′ j W(i)|
[0084] if SINR ′ j SINR max i
[0085] SINR ′ j → SINR max i , and, k i =j
[0086] k i →Ψ
[0087] Among them, Θ is the set of users who are not selected in the selected user group, h′ j Is the channel state information of the jth user in the set Θ, h′ j =h′ j /‖H′ j ‖.
[0088] The user selection method provided by the present invention groups users in advance according to the orthogonality of the codebook, thereby reducing the range of user selection. Compared with the prior art method one that needs to poll all users, the present invention The number of users that need to be polled is only about 1/4 of the number of users that need to be polled in the prior art method. In addition, the present invention obtains the uplink channel state information according to the reciprocity of the uplink and downlink channels, and selects users according to the uplink channel state information. Compared with selecting users based on the PVI feedback from the users in the second method of the prior art, the quantization of PVI can be avoided. System performance degradation caused by errors. In general, the present invention groups users in advance, and then selects users in the selected user group by using the information fed back by the users, so that the computational complexity is greatly reduced with less system overhead.
[0089] The inventor of the present application also simulated the performance of the method of the present invention and the existing method 1 and method 2. For details, please see Figure 6.
[0090] Figure 6 It is a simulation effect diagram of the method of the present invention and existing methods one and two.
[0091] Figure 6 The simulation conditions are shown in Table 2:
[0092] Parameter
[0093] Table II
[0094] Figure 6 It is a simulation effect graph obtained by using the sum capacity as the measurement criterion of the system performance. The abscissa is dB and the ordinate is bit/s/Hz. Among them, curve 1 is the system and capacity curve obtained by using existing method 1, and curve 3 is using The system and capacity curve obtained by the existing method 2, and curve 2 is the system and capacity curve obtained by the method of the present invention.
[0095] by Figure 6 It can be seen that at 30dB, the sum capacity of the existing method 1 is 14 bit/s/Hz, the sum capacity of the existing method 2 is 8.5 bit/s/Hz, and the sum capacity of the present invention is 12.5 bit/s/Hz. It can be seen that Compared with the existing method two, the system performance of the present invention is greatly improved.
[0096] In addition, from the perspective of algorithm complexity, in the existing method 1, after the first user is selected, the selection of the second user requires polling to calculate the projection value of the orthogonal vector corresponding to the channel vector of the 199 users. The selection of the fourth user requires the calculation of the projection values of the orthogonal vectors corresponding to 198 users and 197 users, respectively. The present invention groups users according to the codebook information fed back by the users. In a statistical sense, each user in the divided user group obeys a uniform distribution. By dividing users into four groups, after selecting the first user, the number of users that need to be polled is reduced to 1/4 of the number of users that need to be polled in the existing method 1, because the number of users that need to be polled is reduced Therefore, the complexity of the algorithm of the present invention is greatly reduced compared with the existing method.
[0097] It can be said that the present invention is proposed on the basis of obtaining channel state information through uplink and downlink channel reciprocity and combining codebook orthogonality, and is a compromise solution for achieving complexity and system performance indicators.
[0098] In the following, based on the above method embodiments, the device embodiments and system embodiments of the present invention are given.
[0099] Figure 7 Is the structure diagram of the base station provided by the present invention, such as Figure 7 As shown, the base station includes a storage module 701, a user grouping module 702, a user group selection module 703, and a user selection module 704.
[0100] The storage module 701 stores the codebook grouped according to the orthogonality principle, the channel estimation information fed back by the user terminal, and the codebook information selected according to the channel estimation information.
[0101] The user grouping module 702 groups the user terminals according to the grouping situation of the codebook and the codebook information.
[0102] The user group selection module 703 selects a user group according to the channel estimation information.
[0103] The user selection module 704 selects users from the user group selected by the user group selection module according to the channel estimation information of each user in the user group.
[0104] The user group selection module 702 takes the user with the largest channel vector modulus square value among the users as the selected user group.
[0105] The user selection module 704 traverses all unselected users in the selected user group, calculates the signal-to-noise ratio of each unselected user according to the channel estimation information, and selects the user with the largest signal-to-noise ratio.
[0106] Figure 8 It is the structure diagram of the multiple input multiple output system provided by the present invention, such as Figure 8 As shown, the system includes a user terminal 801 and a base station 802.
[0107] The user terminal 801 stores the codebook grouped according to the orthogonality principle, estimates the channel, selects the codebook according to the channel estimation information, and feeds back the channel estimation information and the selected codebook information to the base station 802.
[0108] The base station 802 groups the user terminals according to the grouping status of the codebook and the codebook information fed back by the user terminal, selects a user group according to the channel estimation information fed back by the user terminal, and selects the user group according to the information of each user in the user group. Channel estimation information selects users.
[0109] The user terminal 801 calculates the signal-to-noise ratio SINR value or the channel quality indicator CQI value corresponding to each codebook according to the channel estimation information, selects the codebook corresponding to the maximum SINR value or the maximum CQI value, and modulates the quantized value of the channel vector modulus And the number PVI of the selected codebook is fed back to the base station 802.
[0110] The base station 802 takes the user with the largest modulus of the channel vector among the users as the selected user, and sets the user group of the user with the largest modulus of the channel vector as the selected user group, and traverses all unselected users Calculate the signal-to-noise ratio of each unselected user based on the channel estimation information, and select the user with the largest signal-to-noise ratio.
[0111] The above are only the preferred embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall include Within the protection scope of the present invention.
