CN112218366B - A distributed uplink multi-user random access method - Google Patents

Abstract

The invention provides a distributed uplink multi-user random access method, which belongs to the field of communication. The method includes: a user who has an access requirement randomly selects a pilot sequence from the pilot sequence set and sends it to the base station, and initiates an access request to the base station; the user who initiates the access request is based on a proportional fairness index broadcast by the base station to the user. The associated offset adjustment standard adjusts its own offset accordingly. After adding the adjusted offset on the basis of its own signal power, judge whether it can compete for the same pilot sequence according to the strong user judgment criterion. The user who wins the competition will resend the selected pilot sequence to the base station; the base station estimates the channel information according to the received secondary pilot information and demodulates the user identification code, and allocates dedicated pilots to the successfully demodulated users resource. By adopting the invention, the basic fairness of the user's access to the base station can be ensured, the access efficiency and the conflict resolution probability of the user can be improved, and the access time delay can be reduced.

Description

A distributed uplink multi-user random access method

technical field

The present invention relates to the field of communications, in particular to a distributed uplink multi-user random access method.

Background technique

Random access refers to the process from when a user sends a random access preamble, from trying to establish a connection with a base station to successfully transmitting signaling. It is the first step for a user to establish an uplink communication connection with a base station. There are two main purposes. The base station establishes an uplink synchronization relationship; the second is to request the base station to allocate uplink resources for it for data transmission.

The traditional contention-based random access scheme means that users send randomly selected pilot sequences to the base station. When multiple users select the same pilot sequence and a pilot collision occurs, the base station centrally solves the pilot collision problem. The goal is to minimize the pilot collision probability, thereby increasing the number of users who successfully access the network. However, in the face of the communication needs of a large number of users, the problem of pilot frequency collision becomes more and more obvious. The centralized solution of pilot frequency collision by base stations occupies too much bandwidth, resulting in large user access delay, low efficiency, and inability to access base stations fairly. And other issues. Therefore, the traditional centralized random access scheme for resolving pilot frequency conflicts has been unable to meet the needs of massive user access scenarios, and it is urgent to propose a novel and efficient random access scheme.

SUMMARY OF THE INVENTION

The embodiment of the present invention provides a distributed uplink multi-user random access method, which can ensure the basic fairness of user access to the base station, improve user access efficiency and conflict resolution probability, and reduce access delay.

The embodiment of the present invention provides a distributed uplink multi-user random access method, the method includes:

A user who has an access requirement randomly selects a pilot sequence from the pilot sequence set and sends it to the base station, and initiates an access request to the base station;

The user who initiates the access request adjusts its own offset accordingly according to the offset adjustment standard associated with the proportional fairness index of the user broadcasted by the base station, and after adding the adjusted offset on the basis of its own signal power, According to the strong user decision criterion, it is judged whether it can win among the users competing for the same pilot sequence, and the winning user resends the selected pilot sequence to the base station;

The base station estimates the channel information to demodulate the user identification code according to the received secondary pilot information, and allocates dedicated pilot resources for the successfully demodulated users.

Further, the user with access requirements randomly selects a pilot sequence from the pilot sequence set and sends it to the base station, and initiating an access request to the base station includes:

The base station broadcasts a reference signal, and each user in the cell estimates its large-scale fading coefficient α _k according to the reference signal, and completes synchronization with the base station;

A user with access requirements randomly selects a pilot sequence P _i from the pilot sequence set P={P ₁ , P ₂ ,...,P _λp } and sends it to the base station, and initiates an access request to the base station, where i =1,2,...,λ _p , where λ _p represents the number of pilot sequences available for orthogonal normalization.

Further, the user who initiates the access request adjusts his own offset accordingly according to the offset adjustment standard broadcasted by the base station that is associated with the proportional fairness index of the user, and adds the adjusted offset on the basis of his own signal power. After shifting the amount, according to the strong user judgment criterion, it is judged whether it can win among users competing for the same pilot sequence, and before the winning user resends the selected pilot sequence to the base station, the method further includes:

The base station obtains the normalized downlink pilot signal according to the received pilot signal, and broadcasts it to each user in the cell as random access response information;

The base station obtains a normalized downlink pilot signal according to the received pilot signal, and broadcasts it to each user in the cell as random access response information, including:

The base station carries out a cross-correlation operation between the received pilot signal Y and any pilot sequence in the pilot sequence set, and obtains the sum y _i of the channel information of all users who select the pilot sequence;

The base station obtains the normalized downlink pilot signal W by normalizing y _i , and broadcasts it to the users in the cell as random access response information.

Further, the pilot signal Y received by the base station is expressed as:

表示P_i的转置；Z为加性高斯白噪声向量；Among them, U _i represents the set of users who select the pilot sequence P _i , i=1,2,...,λ _p , λ _p represents the number of available pilot sequences for orthogonal normalization; w _k is the transmission of user k power; h _k represents the channel between user k and the base station;

represents the transpose of _Pi ; Z is the additive white Gaussian noise vector;

The sum y _i of the channel information of all users who select the pilot sequence P _i is expressed as:

表示P_i的共轭，Z_i表示加性高斯白噪声向量；in,

represents the conjugate of _{Pi, and Z i represents} the additive white Gaussian noise vector;

The normalized downlink pilot signal W is expressed as:

表示P_i的转置。in,

represents the transpose of _Pi .

Further, the user who initiates the access request adjusts his own offset accordingly according to the offset adjustment standard associated with the proportional fairness index of the user broadcasted by the base station, and adds the adjusted value on the basis of his own signal power. After the offset, according to the strong user judgment criterion, it is judged whether it can win among the users competing for the same pilot sequence. The winning user resends the selected pilot sequence to the base station, including:

与其选取的导频序列P_i进行相关运算，得到互相关运算的结果Q_k；The random access response information that user k will receive

Carry out a correlation operation with the selected pilot sequence P _i to obtain the result Q _k of the cross-correlation operation;

According to the obtained Q _k , estimate the sum of the channel information of all users who select the same pilot sequence P _i

User k adjusts its own offset ξ(m _k ) correspondingly according to the offset adjustment standard associated with the proportional fairness index of the user broadcasted by the base station; where m _k represents the proportional fairness index of user k, ξ(m _k ) is an offset related to m _k , and ξ(m _k ) is determined by the offset adjustment standard broadcast by the base station;

共同确定；User k adds an offset ξ(m _k ) on the basis of its own signal power to determine whether it wins the competition according to the strong user decision criterion, where the strong user decision criterion consists of w _k α _k λ _p +ξ(m _k ) and

jointly determined;

The winning user resends the selected pilot sequence to the base station.

表示为：Further, the random access response information received by user k

Expressed as:

表示h_k的共轭转置，W表示归一化下行导频信号，

表示加性高斯白噪声向量；in,

represents the conjugate transpose of h _k , W represents the normalized downlink pilot signal,

represents an additive white Gaussian noise vector;

The result of the cross-correlation operation Q _k is expressed as:

表示为：Sum of channel information

Expressed as:

表示取变量的实部。Among them, max( ) represents the operation of taking the maximum value,

Represents taking the real part of the variable.

Further, the base station formulates a plurality of different offset adjustment standards associated with the proportional fairness index of the user according to the restriction factor, wherein the restriction factor includes one or more factors of access scenario and time change speed;

When the base station broadcasts one of the offset adjustment criteria to a certain cell, each user in the cell searches for the offset ξ(m _k ) corresponding to its own m _k from the offset adjustment criteria broadcasted by the base station.

Further, the adjustment standards for ξ(m _k ) broadcast by the base station all show a uniform law: when the value of m _k increases, ξ(m _k ) shifts to the positive direction; when the value of m _k decreases, ξ( m _k ) is shifted in the negative direction.

Further, the strong user judgment criterion is:

则用户k竞争胜出，用户k将所选的导频序列P_i重新发送至基站；其中，T_k表示用户竞争胜出这一事件；if satisfied

Then the user k wins the competition, and the user k resends the selected pilot sequence P _i to the base station; wherein, T _k represents the event that the user wins the competition;

则用户k竞争失败，随机接入失败；其中，F_k表示用户竞争失败这一事件。if satisfied

Then the user k fails to compete and the random access fails; where F _k represents the event that the user fails to compete.

Further, the secondary pilot information includes: a user identification code and a pilot sequence that the user who wins the competition re-sends to the base station;

The base station estimates the channel information to demodulate the user identification code according to the received secondary pilot information, and allocates dedicated pilot resources for the successfully demodulated users, including:

After the base station receives the pilot sequence of the winning user again, it estimates the channel information of the user;

demodulate the subscriber identity code using the estimated channel information;

If the demodulation is successful, allocate a dedicated pilot resource for the user to complete subsequent data transmission;

If the demodulation fails, the user access fails.

The beneficial effects brought by the technical solutions provided by the embodiments of the present invention include at least:

In the embodiment of the present invention, the distributed pilot conflict resolution strategy is adopted to transfer the pilot conflict problem to the user end, and each user in the cell adjusts the deviation according to the offset adjustment standard broadcasted by the base station and associated with the proportional fairness index of the user. Adjust the offset accordingly, and then add the adjusted offset on the basis of its own signal power to adjust the priority of its own access to the base station, and finally judge whether the competition wins through the strong user judgment criterion, that is to say: guide The problem of frequency collision is solved by the user itself, not by the base station to specify which user wins the competition by replying to the contention resolution message. The offset adjustment standard associated with the proportional fairness index of the user adjusts the priority of its own access to the base station, which can improve the user's access efficiency and conflict resolution probability while ensuring the basic fairness of the user's access to the base station, and reduce the access time. extension.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

1 is a schematic flowchart of a distributed uplink multi-user random access method provided by an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a system model provided by an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, an embodiment of the present invention provides a distributed uplink multi-user random access method, the method includes:

S101, a user with an access requirement randomly selects a pilot sequence from a pilot sequence set and sends it to a base station, and initiates an access request to the base station;

S102, the user who initiates the access request adjusts his own offset accordingly according to the offset adjustment standard associated with the proportional fairness index of the user broadcasted by the base station, and adds the adjusted offset on the basis of his own signal power Then, according to the strong user judgment criterion, it is judged whether it can win among the users competing for the same pilot sequence, and the winning user resends the selected pilot sequence to the base station;

S103, the base station estimates the channel information according to the received secondary pilot information to demodulate the user identification code, and allocates dedicated pilot resources for the users whose demodulation is successful.

The distributed uplink multi-user random access method according to the embodiment of the present invention adopts a distributed pilot conflict resolution strategy to transfer the pilot conflict problem to the user end, and each user in the cell is fair according to the ratio of the user broadcasted by the base station to the user. The offset adjustment standard associated with the index adjusts the offset accordingly, and then adds the adjusted offset on the basis of its own signal power to adjust the priority of its own access to the base station, and finally passes the strong user judgment. The criterion determines whether the competition wins, that is, the pilot collision problem is solved by the user itself, rather than the base station specifying which user wins the competition by replying to the contention resolution message. Each user in the cell adjusts the priority of its own access to the base station by using the offset adjustment standard broadcast by the base station associated with the proportional fairness index of the user, which can ensure the basic fairness of the user's access to the base station and improve the user's access. Efficiency and conflict resolution probability, and reduce access delay.

In this embodiment, in order to simplify the model, it is specified that the base station is located at the center of the cell, the number of configured antennas is M, there are K single-antenna user terminals (referred to as users) in the cell, and λ _p orthogonally normalized available derivatives frequency sequence, and K>>λ _p . The channel between user k (1≤k≤K) and the base station is h _k =[h _1,k ,h _2,k ,...,h _m,k ,...,h _M,k ] ^T , where h _i,k is the channel transmission coefficient between user k and the ith antenna of the base station, which can be determined by the large-scale fading coefficient and the small-scale fading coefficient:

where g _i,k represents the independent and identically distributed small-scale fading coefficient between user k and the ith antenna of the base station, α _k represents the large-scale fading coefficient between user k and the base station, which is usually related to shadow fading and path loss related. When the number M of antennas on the base station side tends to infinity, the channel between user k and the base station has an asymptotically optimal propagation characteristic, namely:

表示h_k的共轭转置。in,

represents the conjugate transpose of h _k .

In the specific implementation of the foregoing distributed uplink multi-user random access method, further, the user with access requirements randomly selects a pilot sequence from the pilot sequence set and sends it to the base station, and initiates an access request to the base station Specifically, the following steps may be included:

A1, the base station broadcasts a reference signal, and each user in the cell estimates its large-scale fading coefficient α _k according to the reference signal, and completes the synchronization with the base station;

A2, a user with access requirement randomly selects a pilot sequence P _i from the pilot sequence set P={P ₁ , P ₂ ,...,P _λp } and sends it to the base station, and initiates an access request to the base station, where , i=1, 2, . . . , λ _p , where λ _p represents the number of available pilot sequences for orthogonal normalization.

In this embodiment, the user who initiates the access request adjusts his own offset accordingly according to the offset adjustment standard broadcasted by the base station that is associated with the proportional fairness index of the user. After the offset, according to the strong user judgment criterion, it is judged whether it can win among the users competing for the same pilot sequence, and before the winning user resends the selected pilot sequence to the base station, the method further includes:

The base station obtains the normalized downlink pilot signal according to the received pilot signal, and broadcasts it to each user in the cell as random access response information.

In this embodiment, the base station obtains the normalized downlink pilot signal according to the received pilot signal, and broadcasts the normalized downlink pilot signal as the random access response information to each user in the cell, which may specifically include the following steps:

B1, the base station carries out a cross-correlation operation between the received pilot signal Y and any pilot sequence in the pilot sequence set, and obtains the sum y _i of the channel information of all users who select this pilot sequence;

In this embodiment, assuming that the pilot sequence selected by user k is P _i , the pilot signal Y received by the base station is expressed as:

表示P_i的转置；Z为加性高斯白噪声(additive white Gaussian noise，AWGN)向量，其元素为独立同分布(independent and identical distribution，i.i.d.)的复高斯变量

σ²为噪声能量。Among them, U _i represents the set of users who select the pilot sequence P _i , i=1,2,...,λ _p , λ _p represents the number of available pilot sequences for orthogonal normalization; w _k is the transmission of user k power; h _k represents the channel between user k and the base station;

represents the transpose of Pi; Z is an additive white Gaussian noise (AWGN) vector whose elements are complex Gaussian variables of independent and identical distribution ( _iid )

σ ² is the noise energy.

In this embodiment, the sum y _i of the channel information of all users who select the pilot sequence P _i is expressed as:

Among them, P _i ^* represents the conjugate of P _i , and Z _i represents the additive white Gaussian noise vector;

In this embodiment, when the number of antennas M tends to infinity, it can be obtained:

Among them, γ _i is the sum of the channel information of all users who select the same pilot, and σ ² is the noise variance;

B2, the base station obtains a normalized downlink pilot signal W by normalizing y _i , and broadcasts it to users in the cell as random access response information.

In this embodiment, the normalized downlink pilot signal W is expressed as:

where P _i ^T represents the transpose of P _i .

In the specific implementation of the foregoing distributed uplink multi-user random access method, further, the user who initiates the access request offsets itself according to the offset adjustment standard broadcasted by the base station and associated with the proportional fairness index of the user. After adding the adjusted offset on the basis of its own signal power, judge whether it can win among users competing for the same pilot sequence according to the strong user judgment criterion, and the winning user will use the selected The re-sending of the pilot sequence to the base station may specifically include the following steps:

与其选取的导频序列P_i进行相关运算，得到互相关运算的结果Q_k；C1, the random access response information that user k will receive

Carry out a correlation operation with the selected pilot sequence P _i to obtain the result Q _k of the cross-correlation operation;

表示为：In this embodiment, the random access response information received by user k

Expressed as:

表示h_k的共轭转置，W表示归一化下行导频信号，

表示加性高斯白噪声向量；in,

represents the conjugate transpose of h _k , W represents the normalized downlink pilot signal,

represents an additive white Gaussian noise vector;

In the present embodiment, the obtained result Q _k of the cross-correlation operation is expressed as:

When the number of antennas M tends to infinity, we can get:

Since the imaginary part of Q _k only contains the noise part, ignoring its imaginary part can obtain the following approximate expression:

C2, according to the obtained Q _k , estimate the sum of the channel information of all users who select the same pilot sequence P _i

表示取变量的实部。Among them, max( ) represents the operation of taking the maximum value,

Represents taking the real part of the variable.

C3, user k correspondingly changes its own offset ξ(m _k ) according to the offset adjustment standard associated with the proportional fairness index of the user broadcast by the base station;

In this embodiment, m _k is the proportional fairness index of user k, and the value of m _k is related to factors such as the access success rate, throughput ratio, etc. It is generally a non-linear relationship and is not equal to 1. The general trend can be expressed as access The lower the access success rate is, the larger the m _k is, the higher the access success rate is, the smaller the m _k is, the larger the throughput proportion is, the smaller the m _{k is, and the smaller the throughput proportion is, the larger the m k is} .

In this embodiment, ξ(m _k ) is an offset related to m _k . In general, ξ(m _k )=0. With the change of m _k , ξ(m _k ) will be within a reasonable range The base station will formulate a number of different offset adjustment standards associated with the user's proportional fairness index according to the restriction factors such as access scenarios and time changes. When the base station broadcasts one of the offset adjustment standards to a certain cell , when the base station broadcasts one of the offset adjustment criteria to a certain cell, each user in the cell searches for the offset ξ(m _k ) corresponding to its own m _k from the offset adjustment criteria broadcast by the base station.

In this embodiment, the offset of the user's power-on is initialized to 0.

In this embodiment, the adjustment standards for ξ(m _k ) broadcast by the base station all show a uniform law: when the value of m _k increases, ξ(m _k ) shifts to the positive direction, that is, the value of ξ(m _k ) increases; when the value of m _k decreases, ξ(m _k ) shifts to the negative direction, that is, the value of ξ(m _k ) decreases.

共同确定；C4, user k adds an offset ξ(m _k ) on the basis of its own signal power and determines whether it wins the competition according to the strong user judgment criterion, wherein the strong user judgment criterion is w _k α _k λ _p +ξ(m _k ) and

jointly determined;

In this embodiment, the signal power of user k itself is w _k α _k λ _p , w _k is the transmit power of user k, α _k represents the large-scale fading coefficient, and λ _p represents the number of available pilot sequences for orthogonal normalization .

In this embodiment, the strong user judgment criterion is:

则用户k竞争胜出，用户k将所选的导频序列P_i重新发送至基站；其中，T_k表示用户竞争胜出这一事件；if satisfied

Then the user k wins the competition, and the user k resends the selected pilot sequence P _i to the base station; wherein, T _k represents the event that the user wins the competition;

则用户k竞争失败，随机接入失败；其中，F_k表示用户竞争失败这一事件。if satisfied

Then the user k fails to compete and the random access fails; where F _k represents the event that the user fails to compete.

In this embodiment, considering that the signal power of some users is too high, they can successfully access every time, or the proportion of throughput after access is too high, which affects the access of other users. The priority of accessing the base station is changed by adjusting the offset. If the user with a smaller proportional fairness index has a smaller offset, the priority of its access to the base station will decrease, so as to ensure that each user in the cell has a lower priority. The fairness of the access base station.

C5, the user who wins the competition resends the selected pilot sequence to the base station.

In this embodiment, the winning user not only needs to re-send the selected pilot sequence to the base station, but also needs to send other information to the base station, such as a user identification code (ID information), so that the base station can assign an exclusive user ID to the user in the next step. pilot resource.

In the specific implementation manner of the foregoing distributed uplink multi-user random access method, further, the secondary pilot information includes: a user identification code and a pilot sequence that is retransmitted to the base station by the user that wins the competition;

The base station estimates the channel information to demodulate the user identification code according to the received secondary pilot information, and allocates dedicated pilot resources for the successfully demodulated users, including:

After the base station receives the pilot sequence of the winning user again, it estimates the channel information of the user;

demodulate the subscriber identity code using the estimated channel information;

If the demodulation is successful, a dedicated pilot frequency resource (specifically: a resource block corresponding to a certain pilot frequency) is allocated to the user, so as to complete the subsequent data transmission;

If the demodulation fails, the user access fails.

且

则表明UE_f竞争失败，UE_n竞争胜出，UE_n接入基站。在这个条件下，UE_n接入成功率上升，m_n减小，UE_f接入成功率下降，m_f增大，UE_n和UE_f下次接入基站时再次查找偏移量调整标准中与m_k相对应的ξ(m_k)，如果UE_n接入后的吞吐量占比过高，则m_n减小，降低其优先级，然后再根据强用户判决准则判决，于是在ξ(m_k)限制下，基站能够实现接入资源的平等分配，从而实现公平优先。Finally, taking the system model shown in FIG. 2 as an example, the distributed uplink multi-user random access method provided in this embodiment is described. The base station (BS) is located in the center of the cell and is equipped with M antennas. The single-antenna users are evenly distributed in different positions of the cell. Suppose an edge user is UE _f and a non-edge user is UE _n , and their distances from the base station are d respectively. _f and d _n , the large-scale fading coefficients estimated by two users according to the reference signal broadcast by the base station are α _f and α _n respectively, at this time α _f <α _n . The edge user UE _f calculates and finds that its proportional fairness index is large, so it searches for ξ(m _f ) corresponding to m _f from the offset adjustment standard broadcast by the base station; the non-edge user UE _n calculates and finds that its proportional fairness coefficient is small , then according to the offset adjustment standard broadcasted by the base station, ξ(m _n ) corresponding to m _n is searched, at this time ξ(m _f )>ξ(m _n ). When they select the same pilot frequency P ₀ to send to the base station, the base station will feed back random access response information (RAR) to them, and UE _f and UE _n respectively send the received random access response information Q _k ^T and pilot sequence P ₀ performs a correlation operation, and then estimates the sum of the channel information of all users who select the pilot sequence P ₀ , that is, formula (12); the signal powers of UE _f and UE _n plus their respective offsets are: w _f α _f λ _p +ξ(m _f ) and w _n α _n λ _p +ξ(m _n ), if

and

It means that UE _f fails in the competition, UE _n wins the competition, and UE _n accesses the base station. Under this condition, the access success rate of UE _n increases, mn decreases, the access success rate of UE _f decreases, and m _f increases, and the next time UE _n and UE _f access the base station, the offset adjustment standard _is searched again. ξ(m _k ) corresponding to m _k , if the proportion of throughput after access by UE _n is too high, then m _n is reduced and its priority is lowered, and then the judgment is made according to the strong user judgment criterion, so in ξ( Under the restriction of m _k ), the base station can realize equal distribution of access resources, thereby realizing fair priority.

In summary, in the distributed uplink multi-user random access method described in the embodiment of the present invention, the base station does not care which users select the pilot sequence and whether the pilot collides, but each user detects in a distributed manner. Whether the selected pilot sequence collides with the pilot sequence selected by other users, if the user and other users have selected the same pilot (that is, collision occurs), the user can calculate the signal power plus signal power based on the large-scale fading coefficient estimated by himself. Adjust the priority of accessing the base station with the changed offset, and judge whether it can win the users competing for the same pilot frequency according to the strong user judgment criterion. Finally, the successful user in the competition re-sends the pilot frequency sequence to the base station.

The distributed uplink multi-user random access method provided by the embodiment of the present invention has the following advantages:

1) Distributed solution of pilot collisions: each user detects pilot collisions in a distributed manner and coordinates by itself, which is conducive to efficient access of multiple users in the cell; in this way, the pressure of the base station to resolve collisions in a centralized manner is transferred to the cell It can reduce user access delay and improve access efficiency.

2) Considering the difference in the ability of users in the cell to access the base station, in order to ensure that each user in the cell can obtain the opportunity to access the base station, in this embodiment, each user in the cell is based on the proportional fairness index broadcast by the base station to the user. The associated offset adjustment standard adjusts the offset accordingly, and then adds the adjusted offset on the basis of its own signal power to adjust the priority of its own access to the base station. This ensures that each user All users can access the base station with roughly the same probability, thereby ensuring the fairness of each user in the cell accessing the base station.

3) When solving the user collision probability problem, pre-calculation is performed at the user, the collision processing occurs between users, and the base station is only responsible for broadcasting the reference signal. When the number of users increases, it will not affect the base station in this embodiment to support user access. The capabilities of the network are a major advantage over existing technologies.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (3)

1. a distributed uplink multi-user random access method is characterized in that, comprising: A user who has an access requirement randomly selects a pilot sequence from the pilot sequence set and sends it to the base station, and initiates an access request to the base station; The user who initiates the access request adjusts its own offset accordingly according to the offset adjustment standard associated with the proportional fairness index of the user broadcasted by the base station, and after adding the adjusted offset on the basis of its own signal power, According to the strong user decision criterion, it is judged whether it can win among the users competing for the same pilot sequence, and the winning user resends the selected pilot sequence to the base station; The base station estimates the channel information to demodulate the user identification code according to the received secondary pilot information, and allocates dedicated pilot resources for the successfully demodulated users; Wherein, the user who initiates the access request adjusts his own offset accordingly according to the offset adjustment standard associated with the proportional fairness index of the user broadcasted by the base station, and adds the adjusted offset on the basis of his own signal power. After determining whether the user can win the competition for the same pilot sequence according to the strong user judgment criterion, before the user who wins the competition resends the selected pilot sequence to the base station, the method further includes: The base station obtains the normalized downlink pilot signal according to the received pilot signal, and broadcasts it to each user in the cell as random access response information; The base station obtains a normalized downlink pilot signal according to the received pilot signal, and broadcasts it to each user in the cell as random access response information, including: The base station carries out a cross-correlation operation between the received pilot signal Y and any pilot sequence in the pilot sequence set, and obtains the sum y _i of the channel information of all users who select the pilot sequence; The base station obtains the normalized downlink pilot signal W by normalizing y _i , and broadcasts it to users in the cell as random access response information; Among them, the pilot signal Y received by the base station is expressed as:

Among them, U _i represents the set of users who select the pilot sequence P _i , i=1,2,...,λ _p , λ _p represents the number of available pilot sequences for orthogonal normalization; w _k is the transmission of user k power; h _k represents the channel between user k and the base station;

represents the transpose of _Pi ; Z is the additive white Gaussian noise vector; The sum y _i of the channel information of all users who select the pilot sequence P _i is expressed as:

in,

represents the conjugate of _{Pi, and Z i represents} the additive white Gaussian noise vector; The normalized downlink pilot signal W is expressed as:

in,

represents the transpose of _Pi ; The user who initiates the access request adjusts his own offset accordingly according to the offset adjustment standard broadcasted by the base station that is associated with the proportional fairness index of the user, and adds the adjusted offset on the basis of his own signal power. After shifting the amount, according to the strong user judgment criterion, it is judged whether it can win among the users competing for the same pilot sequence. The winning user resends the selected pilot sequence to the base station, including: The random access response information that user k will receive

Carry out a correlation operation with the selected pilot sequence P _i to obtain the result Q _k of the cross-correlation operation; According to the obtained Q _k , estimate the sum of the channel information of all users who select the same pilot sequence P _i

User k adjusts its own offset ξ(m _k ) correspondingly according to the offset adjustment standard associated with the proportional fairness index of the user broadcasted by the base station; where m _k represents the proportional fairness index of user k, ξ(m _k ) is an offset related to m _k , and ξ(m _k ) is determined by the offset adjustment standard broadcast by the base station; User k adds an offset ξ(m _k ) on the basis of its own signal power to determine whether it wins the competition according to the strong user decision criterion, where the strong user decision criterion consists of w _k α _k λ _p +ξ(m _k ) and

Determined jointly, α _k represents the large-scale fading coefficient between user k and the base station; The winning user resends the selected pilot sequence to the base station; Wherein, the base station formulates a plurality of different offset adjustment standards associated with the proportional fairness index of the user according to the restriction factor, wherein the restriction factor includes: one or more factors of the access scenario and the speed of time change; When the base station broadcasts one of the offset adjustment criteria to a certain cell, each user in the cell searches for the offset ξ(m _k ) corresponding to its own m _k from the offset adjustment criteria broadcasted by the base station; Among them, the adjustment standards of ξ(m _k ) broadcast by the base station all show a uniform law: when the value of m _k increases, ξ(m _k ) shifts to the positive direction; when the value of m _k decreases, ξ(m _k ) Offset to the negative direction; Among them, the strong user judgment criterion is: If _{Tk is} satisfied:

Then the user k wins the competition, and the user k resends the selected pilot sequence P _i to the base station; wherein, T _k represents the event that the user wins the competition; If F _k is satisfied:

Then the user k fails to compete and the random access fails; where F _k represents the event that the user fails to compete; Wherein, the secondary pilot information includes: a user identification code and a pilot sequence that the user who wins the competition re-sends to the base station; The base station estimates the channel information to demodulate the user identification code according to the received secondary pilot information, and allocates dedicated pilot resources for the successfully demodulated users, including: After the base station receives the pilot sequence of the winning user again, it estimates the channel information of the user; demodulate the subscriber identity code using the estimated channel information; If the demodulation is successful, allocate a dedicated pilot resource for the user to complete subsequent data transmission; If the demodulation fails, the user access fails. 2 . The distributed uplink multi-user random access method according to claim 1 , wherein the user with access requirements randomly selects a pilot sequence from the pilot sequence set and sends it to the base station, and initiates the transmission to the base station. 3 . Access requests include: The base station broadcasts a reference signal, and each user in the cell estimates its large-scale fading coefficient α _k according to the reference signal, and completes synchronization with the base station; Users with access requirements are set from the pilot sequence

A pilot sequence _{P i} is randomly selected from among the base stations and sent to the base station, where an access request is initiated to the base station, where i ₌ 1, 2, . 3. The distributed uplink multi-user random access method according to claim 1, wherein the random access response information received by user k

Expressed as:

in,

represents the conjugate transpose of h _k , W represents the normalized downlink pilot signal,

represents an additive white Gaussian noise vector; The result of the cross-correlation operation Q _k is expressed as:

Sum of channel information

Expressed as:

Among them, max( ) represents the operation of taking the maximum value,

represents the real part of the variable, M represents the number of antennas configured, and σ ² represents the noise variance.

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