Cellular system uplink multiple access enhancement method based on signal spatial gain adjustment and cancellation

Abstract

The application discloses a cellular system uplink multiple access enhancement method based on signal space gain adjustment and cancellation, relates to the field of mobile communication, and aims to solve the problem that the existing space division multiple access technology cannot effectively utilize space resources due to interference among multiple users. The application discloses a cellular system uplink multiple access enhancement method based on signal space gain adjustment and cancellation, which fully utilizes the existing receiver hardware resources and computing power resources on the base station side, adjusts the space gain of each user again on the basis of the original antenna array signal gain of all users, cancels the signals before and after the space gain adjustment, completes secondary processing of the signals, suppresses the inter-user interference of the space division multiple access system, and increases the uplink access user number of the space division multiple access. The inter-user interference suppression capacity of the application is positively correlated with the total intensity of the inter-user interference, and the signal-to-interference-and-noise ratio of each user to be detected can still be optimized when the inter-user interference is very strong.

Description

Technical Field

[0001] This invention belongs to the field of mobile communications. Background Technology

[0002] With the increasing number of users in cellular mobile communication systems and the growing communication demands of users, traditional orthogonal multiple access methods such as frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA) are increasingly unable to meet the communication rate and quality requirements of users within the system. Space division multiple access (SDMA) technology, based on the differences in the geographical location of users and the direction of signal arrival, fully utilizes the spatial resources provided by the antenna array to form a directional beam in the user's direction. This allows for the reception and transmission of multiple user signals using the same time, frequency, and code domain resources. Its high spectral efficiency and high power efficiency have attracted widespread attention from researchers.

[0003] However, spatial division multiple access (SDMA) technology requires stringent preconditions to achieve complete non-interference between users, such as an almost infinite number of antennas and a radio frequency chain commensurate with the number of antennas. These conditions are impractical in engineering implementation, meaning that SDMA systems inevitably face multi-user interference problems. With the trend of deeper reuse of multi-domain resources in 5G and future wireless communication systems, how to efficiently handle interference between users in SDMA using base station resources has become an urgent problem to be solved. To address this, this invention fully utilizes the computing power advantage of the base station to adjust and cancel the spatial domain gain of signals from different users, thereby suppressing multi-user interference and increasing the number of uplink SDMA access users. Summary of the Invention

[0004] This invention aims to address the problem of interference between multiple users in existing spatial division multiple access (SDMA) technologies, which leads to ineffective utilization of spatial resources. Therefore, it proposes an uplink multiple access enhancement method for cellular systems based on signal spatial gain adjustment and cancellation.

[0005] The technical solution for implementing this method is as follows:

[0006] The uplink multiple access enhancement method for cellular systems based on signal spatial gain adjustment and cancellation is characterized by the following steps for a base station configured with R antennas, where R is an integer greater than 1:

[0007] Step 1: The receiving end uses R antennas to receive R analog signals from the wireless channel, and processes the R analog signals through the analog front-end processor to obtain R processed analog signals.

[0008] Step 2: The receiving end performs analog-to-digital conversion on the R-channel processed analog signals obtained in Step 1 to obtain the antenna array metadata before spatial gain adjustment.

[0009] Step 3: The receiver combines the antenna array metadata obtained in Step 2 (before spatial gain adjustment) with the MUSIC algorithm to estimate the number of users M and the angles of arrival θ1, θ2, ..., θ of each user signal. M M is the number of users and is a positive integer;

[0010] Step 4: The receiver calculates the spatial inherent gain G of the antenna array in the direction of arrival angle of M users based on the antenna array spacing and feed current phase. E1 G E2 ... G EM Then, for the M user signals to be detected, steps five through eight are executed in parallel.

[0011] Step 5: Adjust the spatial gain of user m, 1≤m≤M; obtain the spatial gain adjustment result of user m, that is: the antenna array metadata after the spatial gain of user m is adjusted.

[0012] Step 6: Evaluate the effect of the spatial gain adjustment results for user m obtained in Step 5, and then proceed to Step 7;

[0013] Step 7: Perform cancellation enhancement on the transmission signal of user m. The specific cancellation enhancement method is as follows:

[0014] Step 71: Sum the antenna array metadata before spatial gain adjustment described in Step 2 to obtain the antenna array synthesized signal r1(n) before spatial gain adjustment, and send it into the buffer.

[0015] Step 72: Sum the antenna array metadata after spatial gain adjustment described in Step 5 to obtain the synthesized antenna array signal r2(n) after spatial gain adjustment;

[0016] Step 73: Attenuate the summed data r2(n) obtained in step 72 by a factor of κ to obtain the attenuated signal r3(n), where 0 < κ < 1;

[0017] Step 74: Calculate the ratio of κ described in Step 73 to the spatial gain adjustment coefficient γ of user m, and determine the relationship between this ratio and the minimum amplitude attenuation δ3 that the communication signal of user m can withstand. If the ratio is greater than δ3, no cancellation enhancement is performed, and r1(n) is read from the buffer described in Step 71 and output, and then Step 8 is executed; otherwise, Step 75 is executed.

[0018] Step 75: Read the buffer described in Step 71, and perform interference cancellation with the power attenuation signal r3(n) described in Step 73 to obtain the cancellation enhancement signal r(n) for user m and output it. Then, execute Step 8.

[0019] Step 8: Receive and detect the signal of user m output in step 74 or 75, recover valid information, and complete a cellular system uplink multiple access enhancement based on signal spatial domain gain adjustment and cancellation.

[0020] The beneficial effects of this invention are as follows: This invention proposes an uplink multiple access enhancement method for cellular systems based on signal spatial gain adjustment and cancellation. It fully utilizes existing receiver hardware and computing resources on the base station side. Based on the original antenna array gain for all user signals, the spatial gain is adjusted again for each user. The signals before and after spatial gain adjustment are then canceled to complete secondary signal processing, suppressing inter-user interference in the spatial division multiple access system and increasing the number of uplink access users. The inter-user interference suppression capability of this invention is positively correlated with the total intensity of inter-user interference, and it can still optimize the signal-to-interference-plus-noise ratio (SNR) of the signal to be detected for each user even when inter-user interference is very strong. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the base station-side received signal processing process of a cellular system uplink multiple access enhancement method based on signal spatial domain gain adjustment and cancellation according to the present invention.

[0022] Figure 2 This is a flowchart of a single-user spatial gain adjustment and evaluation method for uplink multiple access enhancement in cellular systems based on signal spatial gain adjustment and cancellation, according to the present invention.

[0023] Figure 3 This is a schematic diagram of the single-user signal enhancement process of a cellular system uplink multiple access enhancement method based on signal spatial domain gain adjustment and cancellation according to the present invention. Detailed Implementation

[0024] Specific Implementation Method 1: Combination Figure 1-3 This implementation method is described below. Figure 1 This is a schematic diagram of the base station-side received signal processing process of a cellular system uplink multiple access enhancement method based on signal spatial gain adjustment and cancellation according to the present invention. The uplink multiple access enhancement method is implemented by the following steps:

[0025] For a base station configured with R (R>1) antennas, perform the following steps:

[0026] Step 1: Pass the analog signals received by the R antennas through the analog front-end processor respectively;

[0027] The simulated front-end processor specifically includes:

[0028] Low-noise amplifiers, downconverters, and filters;

[0029] Step 2: Perform analog-to-digital conversion on the analog signal output by the front-end processor in Step 1 to obtain the antenna array metadata before spatial gain adjustment;

[0030] Step 3: Using the antenna array metadata before spatial gain adjustment described in Step 2, combine it with the MUSIC algorithm to estimate the number of users M and the angles of arrival θ1, θ2, ..., θ of each user signal. M ;

[0031] Step 4: Calculate the spatial intrinsic gain G of the antenna array in the direction of arrival angle of M users using the antenna array spacing and feed current phase. E1 G E2 ... G EM Then, for each of the M user signals to be detected, steps five to eight are executed independently and in parallel. Without loss of generality, steps five to eight are described using user m (1≤m≤M) as an example.

[0032] Step 5: Adjust the spatial gain of user m, such as... Figure 2 As shown, the specific adjustment method is as follows:

[0033] Step 51: Set the spatial gain adjustment principle for user m. Let the ideal gain of the antenna array after spatial adjustment in the direction of arrival angle of M users be G. I1 G I2 ... G IM The specific principle for adjusting the spatial domain gain is as follows: Under the premise that the calculation bit width does not overflow, let G... Em For G Im Let G be γ (γ>1) times, Ei For G Ii κ times (i takes all positive integers in [1,M] that are not m, 0<κ<1), where γ and κ are selected according to the requirements of suppression effect and processing complexity;

[0034] Step 5.2: Calculate the adjustment factors β1, β2, ..., β of each antenna array data according to the spatial domain gain adjustment principle. R , where β1, β2, ..., β R The modulus of all of them is 1;

[0035] Step 53: Multiply the antenna array metadata adjustment factors described in Step 52 with the corresponding antenna array metadata before spatial gain adjustment in Step 2 to obtain the antenna array metadata after spatial gain adjustment.

[0036] Step Six: Evaluate the effect of spatial gain adjustment on user m, such as... Figure 2 As shown, the specific evaluation method is as follows:

[0037] Step 6.1: Calculate the actual gain G after spatial domain adjustment of the antenna array in the direction of the arrival angles of M users based on the antenna array spacing, the phase of the feeding current, and the adjustment factor described in Step 5.2 A1 G A2 … G AM ;

[0038] Step 6.2: Calculate the gain change ratios η1, η2, …, η M of the M users before and after the spatial domain gain adjustment, where η k = G Ek / G Ak (k = 1, 2, …, M);

[0039] Step 6.3: Construct a normalized spatial domain gain change ratio vector U. When 1 < m < M, the normalized spatial domain gain change ratio vector U is:

[0040]

[0041] When m takes the value of 1: The constructed normalized spatial domain gain change ratio vector U is:

[0042]

[0043] When m takes the value of M: The constructed normalized spatial domain gain change ratio vector U is:

[0044]

[0045] Step 6.4: Calculate the variance σ 2 of the spatial domain gain change ratio vector U described in Step 6.3;

[0046] Step 6.5: Judge the magnitude relationship between the variance σ 2 and the preset variance threshold . When , execute Step 6.6, otherwise execute Step 6.7;

[0047] Step 6.6: Adjust γ = γ – δ1, κ = κ + δ2 as the new spatial domain gain adjustment principle, and re - execute Steps 5.2 to 6.5, where δ1 and δ2 are adjustment steps (δ1 > 0, δ2 > 0), and are selected according to the requirements for the suppression effect and the processing delay;

[0048] Step 6.7: Output the values of γ and κ and the antenna element data after the spatial domain gain adjustment described in Step 5.3;

[0049] Step 7: Cancel and enhance the transmission signal of user m, as shown in Figure 3 . The specific enhancement method is:

[0050] Step 71: Sum the antenna array metadata before spatial gain adjustment described in Step 2 to obtain the synthesized antenna array signal r1(n) before spatial gain adjustment, and send it to the buffer. Let the transmitted signals of M users be x1(n), x2(n), x3(n), ..., x... M Then, the synthesized signal r1(n) of the antenna array before spatial gain adjustment can be expressed as:

[0051]

[0052] Where z1(n) is the noise signal introduced by the receiver.

[0053] For user m, the signal-to-interference-plus-noise ratio (SIR) before spatial gain adjustment is:

[0054]

[0055] Where P xk Indicates signal x k The average power of (n) (k=1,2,…,M), Let z1(n) represent the average power.

[0056] Step 72: Sum the antenna array metadata after spatial gain adjustment described in Step 67 to obtain the antenna array composite signal r2(n) after spatial gain adjustment;

[0057]

[0058] Where z2(n) represents the sum of the noise signals introduced by the receiver and the spatial gain adjustment process. When the actual gain after spatial adjustment is equal to the ideal gain, the above equation takes the approximate equality sign.

[0059] Step 73: Attenuate the summed data r2(n) obtained in Step 72 by a factor of κ to obtain r3(n):

[0060]

[0061] Step 74: Calculate the ratio of κ to γ ​​mentioned in Step 67, and determine the relationship between the ratio and δ3. If the ratio is greater than δ3, no cancellation enhancement is performed. Read and output r1(n) from the buffer mentioned in Step 71, and then execute Step 8; otherwise, execute Step 75; where δ3<1 indicates the minimum amplitude attenuation that the user m communication signal can withstand.

[0062] Step 75: Read the buffer described in Step 71, and perform interference cancellation with the power attenuation signal described in Step 73 to obtain the cancellation enhancement signal r(n) for user m and output it:

[0063]

[0064] For user m, under ideal conditions, its signal-to-interference-plus-noise ratio (SIR) after spatial gain adjustment is:

[0065]

[0066] in: Let z2(n) represent the average power.

[0067] Therefore, the improvement ratio of signal-to-interference-plus-noise ratio for user m before and after spatial gain adjustment is:

[0068]

[0069] When κ << γ, the signal-to-interference-plus-noise ratio (SIR) improvement for user m is:

[0070]

[0071] Step 8: Receive and detect the user m cancellation enhancement signal output in Step 74 or Step 75 to recover valid information.

[0072] The beneficial effects of this specific implementation method are as follows: This specific implementation method proposes an uplink multiple access enhancement method for cellular systems based on signal spatial gain adjustment and cancellation. It fully utilizes the existing receiver hardware and computing resources on the base station side. Based on the original antenna array's signal gain for all users, it readjusts the spatial gain for each user, and then cancels the signals before and after the spatial gain adjustment, completing secondary signal processing. This suppresses inter-user interference in the spatial division multiple access system and increases the number of uplink access users. The inter-user interference suppression capability of this invention is positively correlated with the total intensity of inter-user interference; even when inter-user interference is very strong, it can still optimize the signal-to-interference-plus-noise ratio (SNR) of the signal to be detected for each user.

Claims

1. A method for enhancing uplink multiple access in cellular systems based on signal spatial gain adjustment and cancellation, characterized in that: for a base station configured with R antennas, where R is an integer greater than 1, the following steps are performed: Step 1: The receiving end uses R antennas to receive R analog signals from the wireless channel, and processes the R analog signals through the analog front-end processor to obtain R processed analog signals. Step 2: The receiving end performs analog-to-digital conversion on the R-channel processed analog signals obtained in Step 1 to obtain the antenna array metadata before spatial gain adjustment. Step 3: The receiver combines the antenna array metadata obtained in Step 2 (before spatial gain adjustment) with the MUSIC algorithm to estimate the number of users M and the angles of arrival θ1, θ2, ..., θ of each user signal. M M is the number of users and is a positive integer; Step 4: The receiver calculates the spatial inherent gain G of the antenna array in the direction of arrival angle of M users based on the antenna array spacing and feed current phase. E1 G E2 ... G EM Then, for the M user signals to be detected, steps five through eight are executed in parallel. Step 5: Adjust the spatial gain of user m, 1 ≤ m ≤ M; obtain the spatial gain adjustment result of user m, that is: the antenna array metadata after the spatial gain of user m is adjusted. The specific method for adjusting the spatial gain of user m is as follows: Step 51: Set the spatial gain adjustment principle for user m: Let the ideal gain of the antenna array after spatial adjustment in the direction of arrival angle of M users be G. I1 G I2 ... G IM The specific principle for adjusting the spatial domain gain is as follows: Under the premise that the calculation bit width does not overflow, let G... Em For G Im γ times, γ > 1; let G Ei For G Ii κ times; where i takes all positive integers in [1, M] that are not m, and γ and κ are selected according to the requirements of suppression effect and processing complexity. Step 5.2: Calculate the adjustment factors β1, β2, ..., β of each antenna array data according to the spatial domain gain adjustment principle. R , where β1, β2, ..., β R The modulus of all of them is 1; Step 53: Multiply the antenna array metadata adjustment factors described in Step 52 with the corresponding antenna array metadata before spatial gain adjustment in Step 2 to obtain the antenna array metadata after spatial gain adjustment for user m. Step 6: Evaluate the effect of the spatial gain adjustment results for user m obtained in Step 5, and then proceed to Step 7; The specific evaluation method for assessing the effect of the spatial gain adjustment results for user m obtained in step five is as follows: Step 61: Calculate the actual gain G of the antenna array after spatial adjustment in the M user arrival angle directions based on the antenna array spacing, feed current phase, and adjustment factor described in Step 52. A1 G A2 ... G AM ; Step 6.2: Calculate the gain change ratios η1, η2, ..., η for M users before and after spatial gain adjustment. M , where η k =G Ek / G Ak (k = 1, 2, ..., M); Step 63: Construct the normalized spatial gain change ratio vector U; Step 64: Calculate the variance σ of the spatial gain change ratio vector U described in Step 63. 2 ; Step 65: Determine the variance σ mentioned in Step 64. 2 The relationship between σ and the preset variance threshold, when σ 2 If the condition is met, proceed to step six six; otherwise, proceed to step six seven. Step 66: Adjust γ = γ – δ1 and κ = κ + δ2 as the new spatial gain adjustment principle, and repeat steps 52 to 65. Here, δ1 and δ2 are the adjustment steps, and δ1 > 0 and δ2 > 0. Both δ1 and δ2 are selected according to the requirements of suppression effect and processing delay. Steps six and seven: Output the values ​​of γ and κ and the antenna array metadata after spatial gain adjustment as described in step five and three; Step 7: Perform cancellation enhancement on the transmission signal of user m. The specific cancellation enhancement method is as follows: Step 71: Sum the antenna array metadata before spatial gain adjustment described in Step 2 to obtain the antenna array synthesized signal r1(n) before spatial gain adjustment, and send it into the buffer. Step 72: Sum the antenna array metadata after spatial gain adjustment described in Step 5 to obtain the synthesized antenna array signal r2(n) after spatial gain adjustment; Step 73: Attenuate the summed data r2(n) obtained in step 72 by a factor of κ to obtain the attenuated signal r3(n), where 0 < κ < 1; Step 74: Calculate the ratio of κ described in Step 73 to the spatial gain adjustment coefficient γ of user m, and determine the relationship between this ratio and the minimum amplitude attenuation δ3 that the communication signal of user m can withstand. When the ratio is greater than δ3, no cancellation enhancement is performed, and r1(n) is read from the buffer described in Step 71 and output. Then, Step 8 is executed. Otherwise, proceed to step seven-five; Step 75: Read the buffer described in Step 71, and perform interference cancellation with the power attenuation signal r3(n) described in Step 73 to obtain the cancellation enhancement signal r(n) for user m and output it. Then, execute Step 8. Step 8: Receive and detect the signal of user m output in step 74 or 75, recover valid information, and complete a cellular system uplink multiple access enhancement based on signal spatial domain gain adjustment and cancellation.

2. The uplink multiple access enhancement method for cellular systems based on signal spatial domain gain adjustment and cancellation according to claim 1, characterized in that... In step one, the analog front-end processor specifically includes: a low-noise amplifier, a downconverter, and a filter; The signal input terminal of the noise amplifier is the signal input terminal of the analog front-end processor; the signal output terminal of the low-noise amplifier is connected to the signal input terminal of the downconverter; the signal output terminal of the downconverter is connected to the signal input terminal of the filter; and the signal output terminal of the filter is the signal output terminal of the analog front-end processor.

3. The uplink multiple access enhancement method for cellular systems based on signal spatial gain adjustment and cancellation according to claim 1, characterized in that, in claim 1, the expression for the antenna array synthesized signal r1(n) before spatial gain adjustment is: In the formula: z1(n) is the noise signal introduced by the receiver, x1(n), x2(n), x3(n), ..., x M (n) represent the transmitted signals of M users respectively.

4. The uplink multiple access enhancement method for cellular systems based on signal spatial gain adjustment and cancellation according to claim 3, characterized in that, in step seven-two, the expression for the synthesized antenna array signal r2(n) after spatial gain adjustment is: In the formula: z2(n) represents the sum of the noise signals introduced by the receiver and the spatial gain adjustment process.

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