A decellularized symbiotic communication transmission method based on wireless energy transmission

Abstract

The present invention relates to the field of wireless communication technology, and more particularly to a decellularized symbiotic communication transmission method based on wireless energy transmission. The method comprises: deploying a certain number of access points (APs), RISs (Resistance Initiators) (RISs), and users in a decellularized system, assuming that each RIS serves the user closest to it, i.e., the number of deployed RISs is the same as the number of APs; during the channel estimation phase, the user has initial energy. When the RIS sends a pilot symbol, the user sends Q pilot symbols. The AP processes the received signal and then uses the MMSE channel estimation method to achieve channel estimation; during the downlink energy transmission phase, the AP sends an energy signal, and both the user and the RIS collect energy; during the uplink data transmission phase, the RIS uses the collected energy sensing data, and the user uses the collected energy for data transmission and the next channel estimation. The present invention significantly reduces computational complexity and channel estimation error, can obtain relatively accurate channel estimation, and significantly reduces energy consumption.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a de-cellularized symbiotic communication transmission method based on wireless energy transmission. Background Art

[0002] The Internet of Things (IoT) is one of the primary applications of 5G and 6G wireless networks, aiming to provide ubiquitous wireless connectivity for massive numbers of devices. Due to the exponential growth in the number of IoT devices, significant energy and spectrum resources are required to support such a large-scale connection. Consequently, symbiotic communication has attracted widespread attention as a new passive IoT transmission solution. Furthermore, decellularized network architectures are considered a key component of 6G, providing higher and more uniform spectrum efficiency for terminals in the system. Smart Reflective Surfaces (RIS), another emerging and promising wireless technology, are considered a promising solution to these issues. Because RIS can reflect radio frequency signals, they can assist in energy transfer between APs and users, further reducing system energy consumption. However, RIS sensing and phase control also require a small amount of energy. Therefore, a decellularized symbiotic communication transmission method based on wireless energy transmission is proposed. Currently, research on channel estimation methods using joint pilot transmission by users and RIS is limited and suffers from numerous shortcomings. However, the present invention effectively reduces computational complexity and channel estimation error, achieving more accurate channel estimation while significantly reducing user energy consumption. Summary of the Invention

[0003] The purpose of the present invention is to address the shortcomings of the prior art and propose a decellularized symbiotic communication transmission method based on wireless energy transmission, which improves the accuracy of channel estimation and reduces the computational complexity by realizing low-energy transmission in a RIS-assisted decellularized massive MIMO symbiotic communication system.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A decellularized symbiotic communication transmission method based on wireless energy transmission comprises the following steps:

[0006] S1: In a decellularized system, each RIS serves a nearby user. M multi-antenna APs, K RISs, and K single-antenna users are deployed. Each AP has N antennas, and each RIS has L units. All APs are connected to the CPU via error-free forward links. All users have an initial energy for channel estimation.

[0007] S2: Channel estimation: The user sends a pilot signal in conjunction with the RIS. The AP performs simple calculations on the signals received in different RIS symbol periods to obtain the signals passing through the direct link and the indirect link, respectively.

[0008] S3: The AP can directly use the MMSE method to estimate the direct link channel and the indirect link channel based on the processed signal;

[0009] S4: Downlink energy transmission phase, all APs send energy signals, and each user and RIS collect energy via a direct link;

[0010] S5: In the uplink information transmission phase, the RIS uses the collected energy to sense the data. The user uses part of the collected energy for data transmission and uses the remaining energy for the next channel estimation.

[0011] S6: Determine whether the user's data has been transmitted. If there is still data to be transmitted, go to step S2.

[0012] Preferably, in step S1, the wireless communication system communicates via a direct link and an indirect link assisted by a RIS. Specifically, the signal sent by the k-th user reaches the m-th AP via two channels, one of which is called a direct link channel, i.e., the channel through which the k-th user directly reaches the m-th AP; and the other is called an indirect link channel, i.e., the channel through which the k-th user reaches the m-th AP via the k-th RIS.

[0013] Preferably, in step S2, during the channel estimation phase, the user jointly transmits a pilot signal with the RIS, and the AP performs simple calculations on the signals received in different RIS symbol periods. The RIS symbol period is Q times the user symbol period, i.e., when the RIS transmits one pilot symbol, the user transmits Q pilot symbols. All pilot symbols transmitted by a user in a coherent block are identical, while the RIS transmits two different pilot symbols, i.e., "+1" and "-1", to the AP in an alternating manner. The specific steps are as follows: in the first RIS symbol period, c i =1, then the total signal z received by the mth AP in the first RIS symbol period m (1) is expressed as:

[0014]

[0015] In the above formula, ρ is the user's uplink pilot transmission power, is the pilot sequence, with a length of τ p Right now Different pilot sequences are orthogonal to each other. Assume K>τ p , then different users will definitely use the same pilot sequence, φ k This is the pilot sequence used by the kth user. In addition, h mk is the direct link channel between the mth AP and the i-th user, and R mkis the spatial correlation matrix between the mth AP and the i-th user. is the indirect link channel between the mth AP and the kth user and Among them G mk is the channel between the kth RIS and the mth AP, h k is the channel between the kth user and the kth RIS, V k is the phase shift matrix of the kth RIS. n1 is the additive noise and σ 2 is the noise power. It should be noted that the user sends Q pilot sequences in each RIS symbol period. In addition, c k It is the pilot signal sent by RIS, and its value is 1 or -1. When RIS sends a pilot with the symbol "+1", c k =1, when RIS sends a pilot with a "-1" symbol, c k =-1. The total signal z received by the mth AP in the second RIS symbol period m (2) is expressed as:

[0016]

[0017] where n2 is additive noise and Through calculation and Then we can get:

[0018]

[0019]

[0020] and They are the signal containing only direct link channels and the signal containing only indirect link channels, n3 and n4 represent additive noise, and all APs perform the same calculation process.

[0021] Preferably, in step S3, the AP can directly use the MMSE method to estimate the direct link channel and the indirect link channel based on the processed signal, and the specific steps are: sufficient statistics of the direct link channel between the mth AP and the kth user and sufficient statistics for indirect link channel estimation Can be expressed as:

[0022]

[0023]

[0024] in, represents the set of users using the same pilot sequence as the kth user, and Depend on and The MMSE estimates of the direct link channel and the indirect link channel can be obtained:

[0025]

[0026]

[0027] In the above formula, and are channel estimates for direct and indirect links, respectively, and also, and Satisfy respectively in, and Can be expressed as:

[0028]

[0029]

[0030] Then the direct link channel estimation error for and in, Indirect link channel estimation error for and in,

[0031] Preferably, in the step S4, during the downlink energy transmission phase, all APs send energy signals, and each user and RIS collect energy via a direct link. The signal received by the kth user and the signal received by the kth RIS They are:

[0032]

[0033]

[0034] in, is the energy signal, p is the downlink transmission power, v is the precoding vector for downlink transmission, and is additive noise. The energy I collected by the kth user can be obtained from the above formula k,user and the energy I collected by the kth RIS k,RIS They are:

[0035]

[0036]

[0037] Preferably, in the uplink information transmission phase in S5, the user uses a portion of the collected energy for data transmission and uses the remaining energy for the next channel estimation. k,user The power of the user for uplink data transmission and next channel estimation can be obtained Among them, τ p , τ e and τ u are respectively the duration of uplink pilot transmission, downlink energy collection and uplink information transmission. m for:

[0038]

[0039] in, The information signal transmitted by the kth user, n m is additive noise.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. In the present invention, each RIS only serves the user closest to it and does not reflect signals from other users. That is, there is a one-to-one correspondence between RIS and users, which effectively enhances the communication between users and APs and improves the spectrum efficiency of the system.

[0042] 2. After the orthogonal pilot sequences are allocated in the present invention, other users who are not allocated pilot sequences can select pilot sequences that have less interference with other users, thereby reducing pilot interference.

[0043] 3. In the present invention, the signals including only direct link channels and only indirect link channels can be separated through simple calculation processing, which greatly reduces the calculation complexity and improves the accuracy of channel estimation.

[0044] 4. The calculation of the present invention is relatively simple and can be implemented at the AP without the need for CPU participation in the calculation;

[0045] 5. In the present invention, users only need a small amount of initial energy for initial channel estimation. All subsequent energy consumed is supplemented by the energy signal sent by the AP. In addition, the energy consumed by RIS sensing data is also supplemented by the energy signal sent by the AP, which greatly reduces energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a flow chart of the steps of the present invention;

[0047] Figure 2 A schematic diagram of a system model of the present invention;

[0048] Figure 3 Schematic diagram of the transmission architecture of the present invention. DETAILED DESCRIPTION

[0049] To make the advantages and technical solutions of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, thereby making a clearer definition of the scope of protection of the present invention. The embodiments described in the present invention are only some of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] like Figure 1 , a decellularized symbiotic communication transmission method based on wireless energy transmission, the specific steps are as follows:

[0051] S1: In a decellularized system, each RIS serves a nearby user. M multi-antenna APs, K RISs, and K single-antenna users are deployed. Each AP has N antennas, and each RIS has L units. All APs are connected to the CPU via error-free forward links. All users have an initial energy for channel estimation.

[0052] S2: Channel estimation: The user sends a pilot signal in conjunction with the RIS. The AP performs simple calculations on the signals received in different RIS symbol periods to obtain the signals passing through the direct link and the indirect link, respectively.

[0053] S3: The AP can directly use the MMSE method to estimate the direct link channel and the indirect link channel based on the processed signal;

[0054] S4: Downlink energy transmission phase, all APs send energy signals, and each user and RIS collect energy via a direct link;

[0055] S5: In the uplink information transmission phase, the RIS uses the collected energy to sense the data. The user uses part of the collected energy for data transmission and uses the remaining energy for the next channel estimation.

[0056] S6: Determine whether the user's data has been transmitted. If there is still data to be transmitted, go to step S2.

[0057] Reference Figure 2 , Figure 2The system model of the present invention is presented, in which the RIS assists the nearest user in sending a pilot sequence while simultaneously sending its own pilot symbol. The system comprises M access points (each equipped with N antennas), K RISs (each equipped with L passive reflector units), K users (each with only one antenna), and one CPU (controlling all APs). All APs are connected to the same CPU via a fronthaul link.

[0058] Reference Figure 3 , Figure 3 The relationship between the user symbol period and the RIS symbol period can be directly seen. In the channel estimation phase, the user and the RIS send pilot signals. Assume that the RIS symbol period is Q times the user symbol period. That is, when the RIS sends one pilot symbol, the user sends Q pilot symbols. All pilot symbols sent by a user in a coherent block are the same, while the RIS sends two different pilot symbols, "+1" and "-1", to the AP in an alternating manner. The AP performs simple calculations on the signals received in different RIS symbol periods. Assume that in the first RIS symbol period, c i =1, then the total signal z received by the mth AP in the first RIS symbol period m (1) is expressed as:

[0059]

[0060] In the above formula, ρ is the user's uplink pilot transmission power, φ is the pilot sequence, and the length is τ p Right now Different pilot sequences are orthogonal to each other. Assume K>τ p , then different users will definitely use the same pilot sequence, φ k This is the pilot sequence used by the kth user. In addition, h mk is the direct link channel between the mth AP and the i-th user, and R mk is the spatial correlation matrix between the mth AP and the i-th user. is the indirect link channel between the mth AP and the kth user and Among them G mk is the channel between the kth RIS and the mth AP, h k is the channel between the kth user and the kth RIS, V k is the phase shift matrix of the kth RIS. n1 is the additive noise and σ 2 is the noise power. It should be noted that the user sends Q pilot sequences in each RIS symbol period. In addition, c kIt is the pilot signal sent by RIS, and its value is 1 or -1. When RIS sends a pilot with the symbol "+1", c k =1, when RIS sends a pilot with a "-1" symbol, c k =-1. The total signal z received by the mth AP in the second RIS symbol period m (2) is expressed as:

[0061]

[0062] where n2 is additive noise and Through calculation and Then we can get:

[0063]

[0064]

[0065] and They are the signal containing only direct link channels and the signal containing only indirect link channels, n3 and n4 represent additive noise, and all APs perform the same calculation process.

[0066] From the above formula, we can get the sufficient statistics of the direct link channel between the mth AP and the kth user: and sufficient statistics for indirect link channel estimation for:

[0067]

[0068]

[0069] in, represents the set of users using the same pilot sequence as the kth user, and Depend on and The MMSE estimates of the direct link channel and the indirect link channel can be obtained:

[0070]

[0071]

[0072] In the above formula, and are channel estimates for direct and indirect links, respectively, and also, and Satisfy respectively in, and Can be expressed as:

[0073]

[0074]

[0075] Then the direct link channel estimation error for in, Indirect link channel estimation error for and in,

[0076] In the downlink energy transmission phase, each user and RIS collect energy via a direct link. Then the signal received by the kth user is and the signal received by the kth RIS They are:

[0077]

[0078]

[0079] in, is the energy signal, p is the downlink transmission power, v is the precoding vector for downlink transmission, and is additive noise. The energy I collected by the kth user can be obtained from the above formula k,user and the energy I collected by the kth RIS k,RIS They are:

[0080]

[0081]

[0082] In the uplink data transmission phase, the user uses part of the collected energy for data transmission and uses the remaining energy for the next channel estimation. k,user The power of the user for uplink data transmission and next channel estimation can be obtained Among them, τ p , τ e and τ u are the durations of uplink pilot transmission, downlink energy collection and uplink information transmission respectively. Then, during uplink data transmission, the signal r received by the mth AP is m for:

[0083]

[0084] in, The information signal transmitted by the kth user, n m is additive noise.

[0085] The descriptions and practices disclosed in this invention are easy to understand and comprehend for those skilled in the art, and modifications and refinements may be made without departing from the principles of the invention. Therefore, modifications and improvements made without departing from the spirit of the invention should also be considered within the scope of protection of this invention.

Claims

1. A decellularized symbiotic communication transmission method based on wireless energy transmission, characterized by: The specific steps are as follows: S1: In a decellularized system, each RIS serves a nearby user. M multi-antenna APs, K RISs, and K single-antenna users are deployed. Each AP has N antennas, and each RIS has L units. All APs are connected to the CPU via error-free forward links. All users have an initial energy for channel estimation. S2: Channel estimation: The user sends a pilot signal in conjunction with the RIS. The AP performs simple calculations on the signals received in different RIS symbol periods to obtain the signals passing through the direct link and the indirect link, respectively. S3: The AP can directly use the MMSE method to estimate the direct link channel and the indirect link channel based on the processed signal; S4: Downlink energy transmission phase, all APs send energy signals, and each user and RIS collect energy via a direct link; S5: In the uplink information transmission phase, the RIS uses the collected energy to sense the data. The user uses part of the collected energy for data transmission and uses the remaining energy for the next channel estimation. S6: Determine whether the user's data has been transmitted. If there is still data to be transmitted, go to step S2; In step S1, the wireless communication system communicates via a direct link and an indirect link assisted by the RIS. Specifically, the signal sent by the kth user reaches the mth AP via two channels: one is called the direct link channel, i.e., the channel from the kth user directly to the mth AP; the other is called the indirect link channel, i.e., the channel from the kth user to the mth AP via the kth RIS. In step S2, the RIS symbol period is Q times the user symbol period, that is, when the RIS sends one pilot symbol, the user sends Q pilot symbols. All pilot symbols sent by a user in a coherent block are the same, and the RIS sends two different pilot symbols, namely "+1" and "-1", to the AP in an alternating manner. In the first RIS symbol period, c i =1, then the total signal z received by the mth AP in the first RIS symbol period m (1) is expressed as: In the above formula, τ p is the duration of uplink pilot transmission, ρ is the uplink pilot transmission power of the user, is the pilot sequence, with a length of τ p Right now Different pilot sequences are orthogonal to each other; assuming K>τ p , then different users use the same pilot sequence, This is the pilot sequence used by the kth user; in addition, h mk is the direct link channel between the mth AP and the i-th user, and h mk ~CN(0,R mk ), R mk is the spatial correlation matrix between the mth AP and the i-th user; is the indirect link channel between the mth AP and the kth user and h mk ~CN(0,R′ mk ), where G mk is the channel between the kth RIS and the mth AP, h k is the channel between the kth user and the kth RIS, V k is the phase shift matrix of the kth RIS; n1 is the additive noise and n1~CN(0,σ 2 I N ), σ 2 is the noise power; where the user sends Q pilot sequences in each RIS symbol period; in addition, c k The pilot signal sent by RIS has a value of 1 or -1. When RIS sends a pilot with a "+1" symbol, c k =1, when RIS sends a pilot with "-1" symbol, c k = -1, the total signal z received by the mth AP in the second RIS symbol period m (2) is expressed as: Where n2 is additive noise and n2~CN(0,σ 2 I N ), through the operation and Then we can get: and are the signals containing only direct link channels and only indirect link channels, respectively. n3 and n4 represent additive noise. All APs perform the same calculation process. In step S3, the specific steps are: sufficient statistics of the direct link channel between the mth AP and the kth user and sufficient statistics for indirect link channel estimation Can be expressed as: Among them, P k represents the set of users using the same pilot sequence as the kth user, and Depend on and The MMSE estimates of the direct link channel and the indirect link channel can be obtained: In the above formula, and are channel estimates for direct and indirect links, respectively, and also, and Satisfy respectively in, and Can be expressed as: Then the direct link channel estimation error for and in, Indirect link channel estimation error for and in, 2. The method for de-cellularized symbiotic communication transmission based on wireless energy transmission according to claim 1, characterized in that: In step S4, the signal received by the kth user is and the signal received by the kth RIS They are: Among them, s~CN(0,1) is the energy signal, p is the downlink transmission power, and v is the precoding vector of the downlink transmission. and is additive noise; the energy I collected by the kth user can be obtained from the above formula k，user and the energy I collected by the kth RIS k，RIS They are:

3. The method for de-cellularized symbiotic communication transmission based on wireless energy transmission according to claim 2, characterized in that: In the S5 described above, according to I k，user The power of the user for uplink data transmission and next channel estimation can be obtained Among them, τ p , τ e and τ u are respectively the duration of uplink pilot transmission, the duration of downlink energy collection and the duration of uplink information transmission; then the signal r received by the mth AP during uplink data transmission m for: Among them, q k ~CN(0,1) is the information signal transmitted by the kth user, n m is additive noise.

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