Hierarchical resource shrinking fluid antenna multiple access method for multi-user uplink

Abstract

This invention discloses a hierarchical resource-shrinking fluid antenna multiple access method for multi-user uplink, comprising establishing a receiving device configured with M fluid antennas and an uplink communication system model of M single-antenna users, sharing the same time-frequency resources; the receiving device determines the user processing order based on path loss and initializes an optional antenna-port resource pool; sequentially selects the antenna-port with the highest signal-to-interference-plus-noise ratio for each user, and then removes all ports of that antenna from the resource pool to achieve hierarchical resource shrinkage; after all ports are determined, users transmit signals simultaneously; the receiving device decodes sequentially and performs serial interference cancellation, and finally calculates the system sum and rate; this invention effectively overcomes the defects of insufficient global gain and unstable decoding performance caused by the lack of coordination between port selection and interference cancellation in the prior art, maximizes the utilization of multi-antenna spatial resources, and significantly improves the system sum and rate and multiple access performance.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, and particularly relates to a hierarchical resource shrinkage fluid antenna multiple access method for multi-user uplink. Background Technology

[0002] With the rapid development of mobile communications and various terminal applications, the uplink faces an urgent need to serve more user devices simultaneously under limited time and frequency resources. Currently, the rise of emerging services such as massive IoT terminals, high-definition video streaming, and industrial data acquisition has led to an explosive growth in the number of uplink access users. Under the traditional multiple access framework, the contradiction between limited time and frequency resources and the ever-increasing number of access users is becoming increasingly prominent. How to effectively improve system capacity and ensure user service quality under resource constraints has become an important research direction in the field of wireless communication.

[0003] To address these challenges, existing technologies primarily focus on two directions. Firstly, non-orthogonal multiple access (NOAMI) technology has been extensively studied. Its core idea is to superimpose multiple user signals onto the same resource and then sequentially decode the user data at the receiver using serial interference cancellation, thereby overcoming the limitations of orthogonal resources and improving system access capabilities. Secondly, fluid antenna technology provides a flexible port switching mechanism for the receiver, allowing a single antenna to be configured with multiple switchable ports, improving link quality by selecting a better receiving location. In practical applications, existing methods typically combine these two approaches: first, selecting the port with the best reception performance from among the multiple ports of a single fluid antenna; then, using serial interference cancellation to decode the superimposed multi-user signals, aiming to improve the overall reception performance of the system with limited resources.

[0004] However, existing technical solutions still have significant shortcomings in practical applications. First, the port selection is limited to the range of a single antenna, failing to fully utilize the overall gain of multiple fluid antennas on the receiving device side, resulting in the selected port not being optimal from a global perspective. Second, the port selection result lacks coordinated design with the subsequent serial interference cancellation processing order, causing some user equipment to still suffer from strong interference during the decoding stage, making it difficult to guarantee stable and reliable decoding performance. This localized and fragmented optimization approach limits system and rate improvements, and results in large performance fluctuations, making it difficult to effectively cope with the co-channel interference challenges in multi-user uplink scenarios. Summary of the Invention

[0005] Purpose of the Invention: The purpose of this invention is to provide a hierarchical resource shrinking fluid antenna multiple access method for multi-user uplink, which aims to overcome the shortcomings of existing technologies where port selection is limited to a single antenna and the lack of coordination with interference cancellation leads to insufficient global gain and unstable decoding performance. By using a hierarchical resource shrinking antenna-port joint determination strategy and co-optimizing with serial interference cancellation, the invention maximizes the global gain of multiple antennas and improves system speed and access performance.

[0006] Technical solution: The hierarchical resource shrinkage fluid antenna multiple access method for multi-user uplink as described in this invention includes the following steps:

[0007] An uplink communication system model is established, which includes a receiving device and M user devices. The M user devices share the same time-frequency resources to send uplink signals to the receiving device. The receiving device is configured with M fluid antennas, and each fluid antenna has N selectable ports.

[0008] The receiving device obtains the path loss from each user equipment to the receiving device and the channel coefficient from each user equipment to each port of each fluid antenna through channel estimation;

[0009] Based on the path loss, the receiving device determines the processing order of each user equipment in ascending order of path loss values.

[0010] Initialize the set of user equipment to be determined to all M user equipment, and initialize the optional antenna-port resource pool to all ports of all fluid antennas;

[0011] The receiving device determines the receiving antenna-port corresponding to each user equipment in sequence according to the processing order. For the user equipment in the current processing order, the signal-to-interference-plus-noise ratio (SIR) of other user equipment whose receiving ports have not yet been determined is used as interference in the current selectable antenna-port resource pool. The antenna-port with the highest SIR is selected as the receiving antenna-port of the user equipment. After determining the receiving antenna-port of the current user equipment, the user equipment is removed from the set of user equipment to be determined, and all ports corresponding to the selected fluid antenna are removed from the selectable antenna-port resource pool to complete the hierarchical resource shrinkage update of the resource pool.

[0012] After the receiving antenna-port determination of all user equipment is completed, all user equipment simultaneously sends its own uplink signal to the receiving equipment, and the receiving equipment obtains the received signal at the receiving antenna-port of each fluid antenna.

[0013] The receiving device decodes the uplink signals of each user equipment in sequence according to the processing order, and performs serial interference cancellation on the decoded uplink signals of the user equipment until the decoding of all user equipment is completed.

[0014] After all user equipment decoding is completed, the achievable rate of each user equipment is calculated based on the signal-to-interference-plus-noise ratio of each user equipment in the corresponding decoding stage, and the system sum rate is obtained by summing the achievable rates of all user equipment to complete the multiple access of multi-user uplink signals.

[0015] The method described in this invention overcomes the limitations of existing technologies where port selection is confined to a single antenna and lacks coordination with serial interference cancellation by establishing an uplink communication system model and configuring multiple fluid antennas. When the receiving device sequentially determines the receiving antenna-port for each user equipment, the processing order is optimized based on path loss. The signal-to-interference-plus-noise ratio (SNR) of each port is calculated using signals from other user equipment whose receiving ports have not yet been determined as interference from the currently available antenna-port resource pool. After selecting the optimal port, all ports of the selected fluid antenna are immediately removed from the resource pool, forming a hierarchical resource contraction joint determination strategy. This allows the selection of antennas and ports to globally coordinate the interference relationships among multiple users, avoiding resource conflicts and local optima. Subsequently, serial interference cancellation is performed sequentially according to the processing order, ensuring that users with lower path loss decoded first provide effective interference removal for users with higher path loss. This tightly coordinates the physical layer selection of antenna-ports with the link layer interference cancellation. Ultimately, this method maximizes the global spatial degree of freedom gain of the multi-antenna system, significantly improves the SNR stability of each user's decoding stage, and achieves overall optimization of system performance, rate, and multiple access performance by accumulating the achievable rates of all users.

[0016] Preferably, each of the user equipment is equipped with a fixed single antenna; there is port correlation between different selectable ports within the same fluid antenna, and the port correlation is determined by port correlation parameters. Characterization, and the port-related parameters satisfy:

[0017]

[0018] in, The normalized length parameter for each fluid antenna is used only to characterize the correlation between different ports within the same fluid antenna, without considering the correlation between different fluid antennas.

[0019] This preferred scheme configures a fixed single antenna for all user equipment and introduces port-related parameters to accurately characterize the correlation between different selectable ports within the same fluid antenna. This allows the receiving equipment to fully anticipate and utilize the spatial correlation characteristics between ports during the hierarchical resource contraction antenna-port joint determination process, thus making the signal-to-interference-plus-noise ratio calculation and optimal port selection more closely match the spatial distribution of the actual physical channel. Since the correlation between different fluid antennas is not considered, the model complexity is effectively controlled, focusing on the refined management of port resources within a single fluid antenna. This further improves the accuracy and rationality of resource elimination in the hierarchical contraction strategy, ensuring that the selected antenna-port combination can maximize global spatial gain in a multi-user interference environment, laying a more reliable signal foundation for the stable execution of subsequent serial interference cancellation.

[0020] Preferably, the channel coefficients are described by a quasi-static flat Rayleigh fading model and satisfy complex Gaussian normalization of unit average power; the noise at the receiving end of the receiving device is additive white Gaussian noise and the noise power is normalized to 1.

[0021] This preferred scheme describes the channel coefficients using a quasi-static flat Rayleigh fading model and sets a complex Gaussian normalization for unit average power. Simultaneously, it models the receiver noise as power-normalized additive white Gaussian noise, constructing a standardized and widely applicable wireless propagation environment for system analysis. Under this setting, the signal-to-interference-plus-noise ratio (SIR) calculated by the receiving device during the hierarchical resource contraction antenna-port joint determination process accurately reflects the statistical characteristics of actual channel fading and noise, making the port selection strategy based on maximizing SIR statistically optimal. Furthermore, the normalized channel and noise power settings simplify the system parameter space, highlighting the dominant role of multi-user interference and spatial resource allocation on performance. This provides a clear theoretical basis for the synergistic optimization of the hierarchical contraction strategy and serial interference cancellation, ensuring that the obtained system and rate performance exhibit good stability and comparability under different channel implementations.

[0022] Preferably, the path loss is determined by the distance between the user equipment and the receiving equipment and a path loss model based on the distance, wherein the path loss model is:

[0023]

[0024] in, Represents the user device index. Indicates the first The distance between a user equipment and a receiving device For reference distance, This is the path loss index.

[0025] This preferred scheme quantifies the path loss between each user equipment and the receiving equipment by introducing a distance-based path loss model, enabling the receiving equipment to accurately sort the processing order according to the actual spatial distribution of users. User equipment with lower path loss is processed earlier, meaning that users with better signal quality are given priority in antenna-port selection and decoding. This design fully utilizes the link layer gain of serial interference cancellation, so that users with strong signals that are decoded first are no longer affected by their own interference after being removed from resources, while users with weak signals can obtain better signal-to-interference-plus-noise ratio conditions by taking advantage of the effective interference cancellation of already decoded users. This path loss model works closely with the hierarchical resource contraction strategy and serial interference cancellation to transform the spatial location differences of users into access order priorities, thereby optimizing the fairness of multi-user uplink access and the overall system throughput at the global level.

[0026] Preferably, the optional antenna-port resource pool is initialized as follows:

[0027]

[0028] in, For optional antenna-port resource pool, Indicates the receiving device number Index of root fluid antenna, This indicates the first [unclear] on the fluid antenna. Index of optional ports, Indicates an antenna-port;

[0029] Each fluid antenna can be assigned to a maximum of one user equipment.

[0030] This preferred scheme establishes clear resource boundary constraints for the hierarchical resource contraction antenna-port joint determination strategy by initializing the optional antenna-port resource pool to all ports of all fluid antennas and explicitly limiting each fluid antenna to be assigned to at most one user equipment. Under this initialization framework, when the receiving equipment selects the optimal antenna-port for each user equipment in the processing order, it can strictly follow the physical constraint of "each antenna serves at most one user", effectively avoiding the port interference coupling problem caused by the same fluid antenna being multiplexed by multiple users. Combined with the hierarchical contraction mechanism, when a port on a fluid antenna is selected, all ports corresponding to that antenna are removed from the resource pool as a whole. This operation unifies antenna-level resource exclusivity with port-level fine selection, so that the resource contraction process retains the flexibility of port selection while satisfying physical constraints, thereby achieving an effective balance between maximizing the global gain of multiple antennas and ensuring the signal separation of multiple users.

[0031] Preferably, when determining the receiving antenna-port corresponding to each user equipment, for the user equipment in the current processing order... Its antenna-port in the currently available antenna-port resource pool The signal-to-interference-plus-noise ratio (SIR) is calculated using the following formula:

[0032]

[0033] in, The processing order is indicated as the first... Bit-level user device index. ; Indicates the transmit signal-to-noise ratio; Indicates user equipment To antenna-port The equivalent channel coefficients are determined by both path loss and channel coefficients. Represents the set of indexes for all user devices; To interfere with the indicator variable, when Time indicates user equipment The signal is included in the interference term in the current calculation. The time indicates that the interference is not included; the interference indicator variable is initialized to the value of 0 for all user equipment. Furthermore, after the user equipment completes the receiving antenna-port determination, its corresponding interference indication variable is set to 0.

[0034] This preferred scheme, through the coordinated design of interference indicator variables and signal-to-interference-plus-noise ratio (SINNR) calculation formulas, deeply integrates the hierarchical resource contraction strategy and the phased characteristics of serial interference cancellation into the antenna-port selection process. When determining the receiving antenna-port for each user equipment in sequence, the interference indicator variable only includes the signals of other user equipment whose receiving ports have not yet been determined in the interference item, while processed users whose resource allocation has been completed are excluded from the interference calculation. This mechanism allows the optimal port selection of the current user to predict the effect of subsequent serial interference cancellation in advance, that is, the interference of decoded users will be eliminated in the actual reception stage, thereby avoiding sacrificing the spatial freedom of the current user to suppress the interference that will be eliminated later. At the same time, after the receiving antenna-port of the current user equipment is determined, its interference indicator variable is immediately set to zero, which further strengthens the synchronization of resource contraction and interference cancellation. This makes the entire multi-user access process form a closed-loop coordination between physical layer port selection and link layer interference processing, which significantly improves the stability of the achievable rate of each user and the global optimality of the system and rate.

[0035] Preferably, the equivalent channel coefficient Due to path loss and channel coefficient Together, we determine that the expression is:

[0036]

[0037] in, Represents the user device index. Indicates the receiving device number Index of root fluid antenna, This indicates the first [unclear] on the fluid antenna. Index of optional ports, Indicates the first Path loss from user equipment to receiving equipment Indicates the first Individual user equipment to antenna-port The channel coefficient.

[0038] This preferred scheme explicitly represents the equivalent channel coefficient as the combined effect of path loss and channel coefficient. It incorporates both the spatial distance attenuation characteristics and small-scale fading fluctuations of users into the signal-to-interference-plus-noise ratio (SINR) calculation, enabling the receiving equipment to make decisions based on comprehensive channel quality when selecting antenna-ports. The path loss term reflects the fundamental differences in signal strength among different users due to spatial distribution variations, echoing the "prioritize those with lower path loss" principle in the processing order. This ensures that users prioritized for processing naturally have better channel conditions during port selection. The channel coefficient term captures the spatial correlation characteristics between different ports on the same fluid antenna, allowing port selection to precisely match instantaneous channel conditions. The combination of these two factors ensures that the hierarchical resource contraction strategy is based on accurate equivalent channel information at each decision step, improving the precision of antenna-port allocation and providing a quantitative basis for the consistency of decoding order and interference removal effect among users in the subsequent serial interference cancellation stage.

[0039] Preferably, the transmit signal-to-noise ratio Transmit power of user equipment Given that the noise power is determined, where the noise power is normalized to 1, then... The transmission power of each user equipment is the same.

[0040] This preferred scheme achieves symmetry and simplification in transmitter power configuration within the system model by setting all user equipment to have the same transmit power and equating the transmit signal-to-noise ratio (SNR) to transmit power. This setting allows the main sources of difference in SNR calculation during the hierarchical resource contraction antenna-port joint determination process of the receiving equipment to focus on path loss, channel coefficient, and multi-user interference distribution, rather than the imbalance of transmit power. This more clearly highlights the dominant role of spatial resource allocation and interference management strategies in system performance. At the same time, the unified transmit power configuration combined with normalized noise power provides a fair transmit benchmark for different user equipment, making path loss the core factor in determining access priority when ranking the processing order. This strengthens the logical consistency between the hierarchical contraction strategy and the co-optimization of serial interference cancellation, facilitating accurate evaluation of the actual gains of the antenna-port selection mechanism on the system and rate in theoretical analysis.

[0041] Preferably, the serial interference cancellation includes: for user equipment with the highest processing order, directly decoding from the received signal corresponding to its receiving antenna-port, treating the uplink signals of other undecoded user equipment as interference during decoding; for user equipment with a lower processing order, first subtracting all decoded uplink signals of user equipment from the received signal corresponding to its receiving antenna-port, then treating the remaining undecoded uplink signals of user equipment as interference, and then performing decoding; wherein, after each successful decoding of a user equipment, the uplink signal corresponding to that user equipment is completely eliminated from the received signal in the subsequent decoding stage.

[0042] This preferred scheme constructs a complete "select first, decode first, eliminate first" closed-loop processing flow by strictly aligning the execution order of serial interference cancellation with the antenna-port allocation order determined in the hierarchical resource contraction strategy. For user equipment with the highest processing order, decoding is performed directly on its selected antenna-port, and other undecoded user signals are treated as interference. Subsequent user equipments first subtract the uplink signals of all decoded users from their selected antenna-port, and then decode the interference of the remaining undecoded users. This mechanism ensures that the antenna-ports independently selected for each user during the hierarchical resource contraction process can be precisely matched with the stage characteristics of serial interference cancellation. First-decoding users do not require additional interference cancellation processing; their port selection only needs to maximize the signal-to-interference-plus-noise ratio (SNR) in the original interference environment. Second-decoding users, on the other hand, anticipate that they will benefit from the interference removal of preceding users during port selection, thus achieving proactive utilization of subsequent cancellation gains during the resource contraction phase. The operation of completely eliminating the signals of already decoded users further ensures the purity of the interference environment in the subsequent decoding phase, enabling multi-user access performance to exhibit stable cumulative gains as the processing sequence progresses. Ultimately, the spatial freedom advantage of the hierarchical resource contraction antenna-port joint determination strategy is deeply integrated with the link-layer interference management capability of serial interference cancellation, achieving an overall improvement in system performance and speed.

[0043] Preferably, the achievable rate of the user equipment is calculated according to the Shannon capacity formula:

[0044]

[0045] in, Indicates user equipment Signal-to-interference-plus-noise ratio (SIR) during the serial interference cancellation decoding stage;

[0046] The system and rate The sum of achievable speeds for all user devices

[0047] .

[0048] This preferred scheme calculates the achievable rate corresponding to the signal-to-interference-plus-noise ratio (SIR) of each user equipment (UE) during the serial interference cancellation decoding stage using the Shannon capacity formula, and sums the achievable rates of all users to obtain the system sum rate, thus constructing a complete quantitative closed loop from physical layer resource allocation to system-level performance evaluation. Under this framework, the synergistic optimization effect of the hierarchical resource contraction antenna-port joint determination strategy and serial interference cancellation is directly mapped to the accumulation of achievable rates and the improvement of the total system throughput. The SIR of each UE already includes the gain it gains due to the removal of interference from preceding users during serial interference cancellation, enabling the system sum rate to truly reflect the global performance advantages brought about by the deep integration of multi-antenna spatial resource contraction allocation and link-layer interference management. This evaluation mechanism provides a clear theoretical basis for verifying the gain of the method of this invention compared to existing technologies, and establishes a unified metric for performance comparison under different user distributions, channel conditions, and resource contraction strategies.

[0049] Beneficial Effects: Compared with the prior art, the present invention has the following significant advantages: 1. The present invention, through a hierarchical resource contraction antenna-port joint determination strategy, extends the selection of multi-user receiving ports from the limitations of a single antenna to a global antenna-port resource pool. Combined with processing order and serial interference cancellation for coordinated optimization, it effectively overcomes the shortcomings of insufficient global gain and unstable decoding performance caused by the lack of coordination between port selection and interference cancellation in the prior art. This maximizes the utilization of multi-antenna spatial resources and significantly improves system performance, speed, and multiple access performance. 2. The present invention introduces a hierarchical resource contraction mechanism in the receiving antenna-port determination process. After the port allocation of a user equipment is completed, all ports of the antenna selected by that user equipment are immediately removed from the available resource pool, ensuring that the selection of subsequent user equipment always occurs in a space with fewer interference sources and more concentrated resources. The process is carried out intermittently, thereby effectively reducing co-channel interference among multiple users, improving the effectiveness of subsequent access and the overall stability of the system; 3. This invention deeply couples the hierarchical resource contraction antenna-port determination result with the serial interference cancellation processing. During the decoding stage, the signals of the decoded user equipment are eliminated sequentially according to the processing order, which significantly reduces the interference faced by subsequent user equipment during decoding, improves the decoding signal-to-interference-plus-noise ratio of each user equipment, and thus enhances the reliability of the uplink signal and the sum rate performance of the system; 4. This invention makes full use of the port-level switchability capability of the fluid antenna and the spatial sampling gain brought by port correlation. Without increasing additional time-frequency resources, it achieves fine matching of multi-user spatial channels through global joint antenna-port selection and hierarchical resource update, improving the resource utilization efficiency and system scalability of multi-user uplink access. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0051] Figure 2 This is a schematic diagram of the receiving link for uplink transmission on a multi-user device according to an embodiment of the present invention;

[0052] Figure 3 This is a graph showing the system average and rate as a function of the number of selectable ports for each fluid antenna in an embodiment of the present invention.

[0053] Figure 4 This is a graph showing the system average and rate as a function of the transmission signal-to-noise ratio in an embodiment of the present invention. Detailed Implementation

[0054] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0055] This invention provides a hierarchical resource-shrinking fluidic antenna multiple access method for multi-user uplink, such as... Figure 1 As shown, the method includes the following steps:

[0056] A communication system model for multi-user uplink is set up. The system model includes multiple user equipment and receiving equipment. Each user equipment is equipped with a fixed single antenna. The receiving equipment is equipped with multiple fluid antennas. Each fluid antenna has multiple selectable ports. The receiving equipment can switch between ports and select the port for receiving.

[0057] Establish an uplink transmission scenario where multiple user devices share the same time-frequency resource. Each user device simultaneously sends uplink signals to the receiving device on the same time-frequency resource. The receiving device performs channel estimation on each selectable port of each fluid antenna and receives the superimposed signal at the port.

[0058] The receiving device obtains the path loss from different user equipment to the receiving device, as well as the channel coefficients of different ports of different fluid antennas from different user equipment to the receiving device, through channel estimation.

[0059] Based on this, the receiving device determines the processing order of user equipment based on the estimated path loss, and user equipment with lower path loss is processed first.

[0060] The receiving equipment determines the receiving "antenna-port" for each user equipment according to the user equipment processing order. During initialization, the set of user signals to be determined for the receiving port is set to all user signals, and the selectable "antenna-port" resource pool includes all ports of all antennas. For the current user equipment in the currently selectable "antenna-port" resource pool, the remaining unallocated port user signals are used as interference. The signal-to-interference-plus-noise ratio (SIR) on each available port is calculated, and the "antenna-port" with the highest SIR is selected as the receiving "antenna-port" for that user equipment. After determining the receiving "antenna-port" for the current user equipment, the user equipment is removed from the pool of devices to be determined. Remove it from the set and delete all ports of its selected antenna from the resource pool; repeat the above process until the receiving "antenna-port" determination of all user equipment is completed; after the receiving "antenna-port" determination of all user equipment is completed, all user equipment simultaneously send their own uplink signals to the receiving equipment, and the receiving equipment obtains the received signals at the selected ports of each fluid antenna; the receiving equipment decodes the user equipment signals according to the user equipment processing order and performs serial interference cancellation processing to remove the interference caused by the decoded user equipment signals to the subsequent undecoded user equipment; repeat the above process until the decoding of all user equipment is completed.

[0061] The achievable rate for each user is obtained based on the signal-to-interference-plus-noise ratio (SIR) corresponding to each user's decoding stage, and the system and rate are calculated to complete the multiple access of multi-user uplink signals.

[0062] In one specific embodiment, the steps include:

[0063] Step 1: Set up a communication system model for multi-user uplink, which includes a receiving device and... A fixed single-antenna user equipment; receiver side configuration Each fluid antenna has One optional port; each user equipment shares the same time-frequency resources to transmit uplink data to the receiving equipment.

[0064] The system model and receiving link are as follows: Figure 2 As shown.

[0065] Define the user equipment index set as and with Indicates the first One user device.

[0066] Define the user equipment index sequence sorted according to the user equipment processing order. ,in This indicates the user device index that is processed first in the order of priority. Indicates the index of the user device last in the processing order.

[0067] Define the optional "antenna-port" set as Its initial value is all port pairs of all fluid antennas:

[0068]

[0069] in, Indicates the receiving device side Index of root fluid antenna, This indicates the first [unclear] on the fluid antenna. Index of optional ports, This indicates a candidate receiver "antenna-port".

[0070] Define interference indicator variables .when Time indicates user equipment The signal is included in the interference term in the current calculation; when Time indicates user equipment The signal is not included in the interference term in the current calculation. During initialization, all... ,Pick .

[0071] Define user equipment The uplink transmission signal is Satisfying the power normalization condition And all user equipment has the same transmission power, denoted as Additive white Gaussian noise is defined as... That is, the noise power is normalized to 1, and the transmit signal-to-noise ratio is defined as . ,Right now .

[0072] Step 2: The receiving device performs channel estimation to obtain channel information. The distance between each user equipment and the receiving equipment is denoted as . The corresponding path loss is denoted as In this embodiment, Determined by the distance path loss model:

[0073]

[0074] in, For reference distance, This is the path loss index.

[0075] Definition of the first The first fluid antenna At each port, the user equipment The channel coefficient to the receiving device is The channel coefficients are described using a quasi-static flat Rayleigh fading model, and the inter-port correlation is determined by correlation parameters. Characterized, and satisfying:

[0076]

[0077] in, For port-related parameters, This is the normalized length parameter for each fluid antenna.

[0078] To characterize port correlation, the channel coefficients before normalization are first defined as follows:

[0079]

[0080] in, , indicating port The corresponding channel coefficient components, This represents the common channel coefficient components that are identical for all ports, and each real Gaussian variable... , , , Independent and satisfying , .

[0081] Furthermore, the channel coefficients are power normalized:

[0082]

[0083] thus, Satisfying the complex Gaussian normalization of unit average power, i.e. .

[0084] The equivalent channel coefficient, which includes path loss and channel coefficients, is defined as follows:

[0085]

[0086] in, Indicates user equipment The receiving device receives the "antenna-port" signal. The equivalent channel coefficient.

[0087] Step 3: The receiving device determines the user equipment processing order based on the path loss obtained from the channel estimation in Step 2. Preferably, Smaller user devices are processed first. That is, according to... Sort the sequence from smallest to largest to get the sequence .

[0088] Step 4: The receiving device follows... The receiving "antenna-port" corresponding to each user equipment signal is determined sequentially.

[0089] For the current user In any candidate At this location, the signal-to-interference-to-noise ratio is:

[0090]

[0091] in, Indicates user equipment to receiving device The equivalent channel coefficient, where "1" in the denominator represents the normalized noise power.

[0092] User equipment The branch selection result can be expressed as:

[0093]

[0094] After completing user equipment After the receiving "antenna-port" is determined, the user equipment... Remove from the set of user equipment to be determined; and perform a hierarchical resource shrinkage update on the optional "antenna-port" resource pool: from Delete the selected fluid antenna All port pairs on the antenna are configured so that the remaining ports of the fluid antenna are no longer involved in the subsequent user equipment reception "antenna-port" determination; and so on. , indicating user equipment The receiving "antenna-port" has been determined, and its signal will no longer be included in the signal-to-interference-plus-noise ratio (SNR) calculation for subsequent port determination. At this point, the remaining user equipment that has not yet been determined meets the requirements. The corresponding signal is still included in the interference items determined by the subsequent ports.

[0095] For current user equipment In any candidate At this location, the signal-to-interference-to-noise ratio is:

[0096]

[0097] in , Therefore, the above equation is equivalent to:

[0098]

[0099] The corresponding "antenna-port" determination result is:

[0100]

[0101] And similarly, the user removes all ports associated with the selected antenna from... The deleted resource pools are updated hierarchically.

[0102] As the processing sequence continues to the next user equipment At that time, for any candidate User equipment The signal-to-interference-plus-noise ratio at the port can be expressed as:

[0103]

[0104] The result of its "antenna-port" determination is as follows:

[0105]

[0106] After completing user equipment After the receiving "antenna-port" is determined, the user equipment... Remove from the set to be determined, and its selected antennas All ports from Delete, and at the same time... Repeat the above process until the "antenna-port" determination for all user equipment is completed.

[0107] Step 5: After determining the receiving "antenna-port" for all user equipment, all user equipment simultaneously transmits uplink signals to the receiving equipment. The receiving equipment obtains superimposed received signals at the selected ports of each fluid antenna. For the receiving equipment... The first fluid antenna Signals can be received at one of the optional ports:

[0108]

[0109] in, For receiving device number The first fluid antenna Additive white Gaussian noise at each port, with noise power normalized. Additive white Gaussian noise with zero mean and unit variance.

[0110] Step Six: After obtaining the superimposed received signal in Step Five, the receiving device decodes the user equipment signal sequentially according to the user equipment processing order and performs serial interference cancellation.

[0111] At the start of the signal decoding phase, reinitialization is performed on all... Pick Once a user equipment successfully decodes and completes serial interference cancellation, its corresponding... This ensures that the signal is no longer included in the interference components during subsequent decoding by user equipment. Under ideal serial interference cancellation conditions, the interference components corresponding to the decoded user equipment are eliminated from the received signal.

[0112] For user equipment In the selected The signal-to-interference-plus-noise ratio at this point is expressed as:

[0113]

[0114] in, Indicates user equipment The equivalent channel coefficients on the selected receiving "antenna-port"; Indicates user equipment It still participates in the superposition as if the interference has not been eliminated. This indicates that the user equipment signal has been eliminated by serial interference and will not be included in subsequent interference calculations.

[0115] Under ideal serial interference cancellation conditions, user equipment After decoding, the interference components are eliminated from the received signal at the corresponding "antenna-port" of the user equipment, and then... Therefore, it will no longer be included in the user equipment calculation process in subsequent user equipment processing. The resulting interference; the receiving equipment then enters the next user equipment. Signal decoding and serial interference cancellation processing.

[0116] For user equipment In the selected The signal-to-interference-plus-noise ratio at this point is expressed as:

[0117]

[0118] Because at this time and The above formula can be simplified to:

[0119]

[0120] The first one The formula is a variable with an activity indicator. The expression; in the current processing At that time, user equipment that has eliminated interference satisfy The remaining unprocessed user equipment meets the requirements. Therefore, it can be simplified to the second one. formula.

[0121] For user equipment After completing signal decoding and performing serial interference cancellation, let This ensures that the signal is no longer included in the interference items during subsequent user equipment decoding and enters the signal decoding and serial interference cancellation processing of the next user equipment.

[0122] As the processing order continues to proceed to subsequent users At that time, the receiving device is in the selected branch The signal-to-interference-plus-noise ratio on the signal can be expressed as

[0123]

[0124] When user equipment After decoding and serial interference cancellation are completed, repeat the above decoding and serial interference cancellation process until decoding of all user equipment is completed.

[0125] Step 7: Based on the signal-to-interference-plus-noise ratio obtained in Step 6, calculate the user achievable rate and the system rate, and the user equipment rate. The reachable rate is expressed as:

[0126]

[0127] After decoding of all user devices is complete, the system and rate are expressed as follows:

[0128]

[0129] in, The total in a single simulation experiment The sum of the rates of each user device.

[0130] To verify the beneficial effects of the present invention, the following steps will be implemented:

[0131] Set the normalized fluid antenna length parameter to Set the number of system user devices to Equipment on the receiving side Root fluid antennas and each antenna has There are 10 optional ports, of which exist Equally spaced values ​​within the range are used to compare the reception performance under different selectable port numbers. User equipment performs uplink transmission on the same time-frequency resource, and the transmission signal-to-noise ratio is taken as... To reflect the difference in user equipment location, the distance between the user equipment and the receiving device is set to be within [a certain range]. Equidistant equipment within the range, among which , Reference distance is taken Path loss index is taken .

[0132] Figure 3This embodiment demonstrates the system average and rate as a function of the number of selectable ports for each fluid antenna. The graph shows the changing curves. The blue dotted curve corresponds to the traditional FAMA scheme, where the receiving equipment pre-fixes the correspondence between user equipment and fluid antennas, selecting ports only from the set of ports corresponding to the fluid antennas, and does not perform serial interference cancellation during the decoding phase. The yellow triangular curve corresponds to the traditional joint selection FAMA scheme, which jointly determines the receiving "antenna-port" from the currently available candidate set of receiving "fluid antenna-port" and locks the corresponding fluid antenna, but does not perform serial interference cancellation during the decoding phase. The orange diamond curve corresponds to the traditional FAMA-SIC scheme, which, based on fixing the correspondence between user equipment and fluid antennas and performing port selection, performs serial interference cancellation according to the user equipment processing order during the decoding phase to remove interference caused by decoded user equipment to subsequent user equipment. The purple square curve corresponds to the proposed scheme, which, after jointly selecting the receiving "antenna-port" and locking the corresponding fluid antenna, dynamically updates the remaining interference state in conjunction with serial interference cancellation, thereby providing a more favorable interference environment for subsequent user equipment. As shown in the graph, with… With the increase of the number of ports, the average system and speed of all four schemes show an upward trend, and the proposed scheme consistently outperforms the other three traditional schemes with the same number of ports. This is because the increased number of selectable ports expands the selection space of the receiving "antenna-port," making it easier for the receiving device to obtain a better receiving "antenna-port." Simultaneously, joint selection allows the receiving device to move beyond the pre-fixed user equipment-fluid antenna correspondence and directly select a better combination from the currently available candidate "antenna-ports," further improving the receiving port selection effect. Furthermore, the proposed scheme dynamically reduces the residual interference level through serial interference cancellation during per-user equipment processing, further improving the system and speed. For example, when... At that time, the average total system rate of the traditional FAMA method was approximately 10.22 bit / s / Hz, the traditional joint selection FAMA scheme was approximately 12.29 bit / s / Hz, the traditional FAMA-SIC scheme was approximately 21.42 bit / s / Hz, while the proposed scheme was approximately 23.67 bit / s / Hz. Therefore, the proposed scheme can effectively improve the overall system rate performance in multi-user uplink scenarios, thus verifying the beneficial effects of the present invention.

[0133] To further verify the performance improvement effect of the multi-user device uplink receiving method described in this invention under different transmit signal-to-noise ratio conditions, all parameters except the transmit signal-to-noise ratio are kept consistent with those in Example 1, and the number of selectable ports for each fluid antenna is fixed at [value missing]. Other system parameters (including) , User equipment distance range Path loss index (etc.) remains consistent with Example 1, by changing the transmit signal-to-noise ratio And statistically analyze the changes in the system average and rate. Specifically, let The performance gain brought about by the method described in this invention was verified by taking values ​​in the range of 0 to 30 dB.

[0134] Figure 4 Demonstrates a fixed number of ports Under these conditions, the average system and rate in this embodiment vary with the transmitted signal-to-noise ratio. The graph shows the changing curves. In the graph, the blue dotted curves correspond to the traditional FAMA scheme, the yellow triangular curves correspond to the traditional joint selection FAMA scheme, the orange diamond curves correspond to the traditional FAMA-SIC scheme, and the purple square curves correspond to the proposed scheme. As can be seen from the graph, with... As the coefficient of performance increases, the average system performance and speed of all four schemes show an upward trend, and at the same... Under these conditions, the proposed scheme consistently outperforms the other three traditional schemes. This is because the increased transmit signal-to-noise ratio (SNR) leads to increased effective received signal power, thereby improving the achievable data rates of each user equipment (UE). Simultaneously, joint selection allows the receiving equipment to move beyond pre-defined UE-fluid antenna correspondences and directly select a better combination from currently available candidate "antenna-port" pairs. Furthermore, the combination of serial interference cancellation reduces the impact of multi-UE superimposed interference on subsequent UE decoding, thus exhibiting a more significant performance advantage in the medium-to-high SNR region. For example, when… At the same time, the average total system rate of the conventional method is approximately 9.85 bit / s / Hz, the conventional joint selection FAMA scheme is approximately 12.11 bit / s / Hz, the conventional FAMA-SIC scheme is approximately 24.15 bit / s / Hz, while the proposed scheme is approximately 26.88 bit / s / Hz. Therefore, the proposed scheme can achieve higher system and data rates under different signal-to-noise ratio conditions, thus verifying the beneficial effects of the present invention.

Claims

1. A hierarchical resource shrinking fluid antenna multiple access method for multi-user uplink, characterized in that, Includes the following steps: An uplink communication system model is established, which includes a receiving device and M user devices. The M user devices share the same time-frequency resources to send uplink signals to the receiving device. The receiving device is configured with M fluid antennas, and each fluid antenna has N selectable ports. The receiving device obtains the path loss from each user equipment to the receiving device and the channel coefficient from each user equipment to each port of each fluid antenna through channel estimation; Based on the path loss, the receiving device determines the processing order of each user equipment in ascending order of path loss values. Initialize the set of user equipment to be determined to all M user equipment, and initialize the optional antenna-port resource pool to all ports of all fluid antennas; The receiving device determines the receiving antenna-port corresponding to each user equipment in sequence according to the processing order. For the user equipment in the current processing order, the signal-to-interference-plus-noise ratio (SIR) of other user equipment whose receiving ports have not yet been determined is used as interference in the current selectable antenna-port resource pool. The antenna-port with the highest SIR is selected as the receiving antenna-port of the user equipment. After determining the receiving antenna-port of the current user equipment, the user equipment is removed from the set of user equipment to be determined, and all ports corresponding to the selected fluid antenna are removed from the selectable antenna-port resource pool to complete the hierarchical resource shrinkage update of the resource pool. In determining the receive antenna-ports corresponding to each user equipment, for the user equipment of the current processing order the signal-to-interference-and-noise ratio on the antenna-ports in the current pool of alternative antenna-ports resources is calculated according to the following formula: SINR = 10 log10 ( SINRbase + SINRoffset ) ;in, The processing order is indicated as the first... Bit-level user device index. ; Indicates the transmit signal-to-noise ratio; Indicates user equipment To antenna-port The equivalent channel coefficients are determined by both path loss and channel coefficients. Represents the set of indexes for all user devices; To interfere with the indicator variable, when Time indicates user equipment The signal is included in the interference term in the current calculation. The time indicates that the interference is not included; the interference indicator variable is initialized to the value of 0 for all user equipment. And after the user equipment completes the receiving antenna-port determination, its corresponding interference indication variable is set to 0; After the receiving antenna-port determination of all user equipment is completed, all user equipment simultaneously sends its own uplink signal to the receiving equipment, and the receiving equipment obtains the received signal at the receiving antenna-port of each fluid antenna. The receiving device decodes the uplink signals of each user equipment in sequence according to the processing order, and performs serial interference cancellation on the decoded uplink signals of the user equipment until the decoding of all user equipment is completed. After all user equipment decoding is completed, the achievable rate of each user equipment is calculated based on the signal-to-interference-plus-noise ratio of each user equipment in the corresponding decoding stage, and the system sum rate is obtained by summing the achievable rates of all user equipment to complete the multiple access of multi-user uplink signals.

2. The method according to claim 1, characterized in that, Each user equipment is equipped with a fixed single antenna; there is port correlation between different selectable ports within the same fluid antenna, and the port correlation is determined by port correlation parameters. Characterization, and the port-related parameters satisfy: ;in, The normalized length parameter for each fluid antenna is used only to characterize the correlation between different ports within the same fluid antenna, without considering the correlation between different fluid antennas.

3. The method according to claim 1, characterized in that, The channel coefficients are described by a quasi-static flat Rayleigh fading model and satisfy complex Gaussian normalization of unit average power; the noise at the receiving end of the receiving device is additive white Gaussian noise and the noise power is normalized to 1.

4. The method according to claim 1, characterized in that, The path loss is determined by the distance between the user equipment and the receiving equipment and a path loss model based on the distance, wherein the path loss model is: ;in, Represents the user device index. Indicates the first The distance between a user equipment and a receiving device For reference distance, This is the path loss index.

5. The method according to claim 1, characterized in that, The optional antenna-port resource pool is initialized as follows: ;in, For optional antenna-port resource pool, Indicates the receiving device number Index of root fluid antenna, This indicates the first [unclear] on the fluid antenna. An index of optional ports, Indicates an antenna-port; Each fluid antenna can be assigned to a maximum of one user equipment.

6. The method according to claim 1, characterized in that, The equivalent channel coefficient Due to path loss and channel coefficient Together, we determine that the expression is: ;in, Represents the user device index. Indicates the receiving device number Index of root fluid antenna, This indicates the first [unclear] on the fluid antenna. An index of optional ports, Indicates the first Path loss from user equipment to receiving equipment Indicates the first Individual user equipment to antenna port The channel coefficient.

7. The method according to claim 1, characterized in that, The transmit signal-to-noise ratio Transmit power of user equipment Given that the noise power is determined, where the noise power is normalized to 1, then... The transmission power of each user equipment is the same.

8. The method according to claim 1, characterized in that, The serial interference cancellation includes: for user equipment (UE) with the highest processing order, decoding is performed directly from the received signal corresponding to its receiving antenna-port, and the uplink signals of other UEs that have not been decoded are considered as interference during decoding; for UEs with a lower processing order, all decoded uplink signals of UEs are first subtracted from the received signal corresponding to its receiving antenna-port, and the remaining unecoded uplink signals of UEs are considered as interference before decoding is performed; wherein, after each successful decoding of a UE, the uplink signal corresponding to that UE is completely eliminated from the received signal in the subsequent decoding stage.

9. The method according to claim 1, characterized in that, The achievable rate of the user equipment is calculated according to the Shannon capacity formula: ;in, Indicates user equipment Signal-to-interference-plus-noise ratio (SIR) during the serial interference cancellation decoding stage; The system and rate The sum of achievable speeds for all user devices 。

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