TWI633802B - Cooperative communication method and system - Google Patents

Abstract

A cooperative communication method and system for a plurality of transmitting end devices and a plurality of receiving end devices respectively corresponding to a plurality of transmitting end devices. In the first phase, at least one of the plurality of transmitting device devices performs the first stage precoding using the corresponding multicast precoding matrix, and transmits the data that has performed the first stage precoding to the other than itself. a transmitting device, and then in a second phase, the plurality of transmitting devices perform the second-stage precoding using the corresponding joint precoding matrix for the data received in the first phase, and the second phase precoding has been performed The data is transmitted to a plurality of receiving devices respectively corresponding to the plurality of transmitting devices.

Description

 Cooperative communication method and system  

The present invention relates to a cooperative communication method and system, and more particularly to a cooperative communication method and system for a plurality of transmitting end devices and a plurality of receiving end devices.

Device-to-device (D2D) communication is a technology in which devices can directly transmit to each other without relaying through a base station, which can improve data transmission rate between devices and spectrum utilization of the system. As the number of user devices increases, and the amount of data for D2D communication increases, the system is bound to accommodate a large number of D2D devices that are simultaneously transmitted. Therefore, the interference between the D2D devices must also be considered. How to improve communication quality in the presence of the aforementioned factors in D2D communication technology is a key issue in the current market.

In the relay transmission technology, the data source point may first transmit their information to a designated relay point, and the designated relay point transmits the information to the target location, so the relay point is only responsible for the data source point and the target location. The information is transferred without transmitting its own information, so there is no need to allocate resources between the source and the relay. Compared with this, when each transmitting end of the D2D communication system will act as a relay point of other transmitting ends, each transmitting end needs to assist in transferring the data of other transmitting ends in addition to transmitting its own data. At this time, each transmitting end needs to allocate resources between transmitting its own information and transferring information of other transmitting ends, and also needs to ensure that each transmitting end can obtain an improvement in transmission performance under mutual relay transmission.

In order to solve the problems of the prior art and other problems, the present disclosure discloses a cooperative communication method and system for a plurality of transmitting end devices and a plurality of receiving end devices respectively corresponding to the plurality of transmitting end devices.

In an embodiment, the cooperative communication method of the present invention includes: in the first phase, at least one of the plurality of transmitting end devices performs the first stage precoding using the corresponding multicast precoding matrix, and the executed The first stage precoded data is transmitted to other transmitting end devices other than itself in the plurality of transmitting end devices; and in the second phase, the plurality of transmitting end devices access the data received in the first stage Performing a second stage precoding using a corresponding joint precoding matrix, and transmitting the data that has been subjected to the second stage precoding to the plurality of receiving end devices corresponding to the plurality of transmitting end devices, wherein the group broadcasting pre The calculation of the coding matrix and the joint precoding matrix is based on the estimated transmission rate or the estimated transmission power of the plurality of transmitting devices in the first phase and the second phase.

In another embodiment, the cooperative communication system of the present invention includes: a plurality of transmitting end devices, each of the plurality of transmitting end devices includes a signal transceiver and a processor; and a plurality of receiving end devices respectively corresponding to the a plurality of transmitting end devices, each of the plurality of receiving end devices including a signal transceiver and a processor, wherein in the first phase, a processor of at least one of the plurality of transmitting end devices is configured to And performing, by using the corresponding multicast precoding matrix, the first stage precoding, and the data that has been executed in the first stage precoding is transmitted to the multiple transmissions by the at least one of the plurality of transmitting end devices a transmitting device other than itself in the end device; and in the second phase, the plurality of processors of the plurality of transmitting devices are configured to utilize the corresponding joint pre-commitment for the data received in the first phase Encoding the matrix to perform the second stage precoding, and the data that has been subjected to the second stage precoding is transmitted to the plurality of transmitting ends via the plurality of signal transceivers of the plurality of transmitting end devices The plurality of receiving devices of the device, and wherein the plurality of processors of the plurality of transmitting devices are configured to determine an estimated transmission rate of the plurality of transmitting devices in the first phase and the second phase or The predicted transmission power calculates the multicast precoding matrix and the joint precoding matrix.

Thereby, the plurality of transmitting end devices of the present case perform data sharing transmission in the first stage and perform cooperative joint transmission in the second stage to transmit the data to the plurality of receiving end devices respectively corresponding to the plurality of transmitting end devices, and according to The two-stage transmission rate and the two-phase power are used to calculate the multicast precoding matrix used in the first phase and the joint precoding matrix used in the second phase to reduce the multiple receptions of the plurality of transmission devices The interference between the transmissions of the end devices increases the transmission rate and increases the number of D2D devices that the system can accommodate to perform simultaneous transmission, and improves the spatial spectrum utilization.

11, 21‧‧‧ Signal Transceiver

12, 22‧‧‧ processor

13, 23‧‧‧ memory

51‧‧‧dotted box

52‧‧‧solid frame

53‧‧‧ arrow

54‧‧‧Virtual data array, rate gain array and energy array

BS‧‧‧ base station

CU‧‧‧ users

DT‧‧‧Transport device

DR‧‧‧ Receiver device

D _k [ t ]‧‧‧Virtual data queue

E _k [ t ]‧‧‧ energy array

NW‧‧‧ noise whitening

O _k [ t ]‧‧‧ rate gain queue

S71~S77‧‧‧Steps

S81~S84‧‧‧Steps

t‧‧‧Communication time

η ₁ , η ₂ ‧ ‧ time ratio

1A is a schematic diagram of a cooperative communication system in the present case; FIG. 1B is a schematic diagram of a transmitting end device and a receiving end device in the present case; FIG. 2 is a schematic diagram of a cooperative communication system and method in the present case divided into two stages; 3 is a schematic diagram of the first stage precoding of the cooperative communication system and method in this case; Fig. 4 is a schematic diagram of the second stage precoding of the cooperative communication system and method of the present case; Fig. 5 is the cooperative communication system of the case And the method of the transmitting end device calculates a schematic diagram of the precoding matrix of the first phase and the second phase; the figures 6A, 6B, and 6C are the virtual data queues, the rate gain queues, and the cooperative communication systems and methods used in the present invention, respectively. Schematic diagram of the energy queue; Figure 7 is a schematic diagram of the flow of the first stage and the second stage precoding matrix for the cooperative communication system and method of the present case; and Fig. 8 is a schematic flow chart of the cooperative communication method of the present case.

The embodiments of the present invention are described below by way of specific examples, and those skilled in the art can readily appreciate the other advantages and functions of the present invention from the disclosure herein. It is to be understood that the structure, the proportions, the size and the like of the present invention are only used in conjunction with the disclosure of the specification for the understanding and reading of those skilled in the art, and are not intended to limit the implementation of the present invention. Conditions, the modification of any structure, the change of the proportional relationship or the adjustment of the size shall not fall within the scope of the technical content disclosed in this case without affecting the effects and the objectives that can be achieved in this case. .

Please refer to FIG. 1A. The cooperative communication system of the present case includes K to D2D, that is, the cooperative communication system of the present case includes K transmitter devices DT (D2D Transmitter) and K receiver devices DR (D2D Receiver), each transmitting device The DT corresponds to a receiving device DR, and each transmitting device DT has its own data to be transmitted. Furthermore, each transmitter device DT having N _t antennas and each receiver device DR segment having N _T antennas. The cooperative communication system of the present invention further includes a base station BS and a user CU (Cellular User), and the user CU may have multiple antennas and transmit the base station BS (Base Station) in the uplink. In the present embodiment, the K transmitting end devices and the K receiving end devices know the statistical characteristics of the interference from the user CU and the interference caused to the base station BS.

Referring to FIG. 1B, each transmitting device DT includes a signal transceiver 11, a processor 12, and a memory 13 connected to the processor 12. Each transmitting device DR includes a signal transceiver 21 and a processor. 22 and a memory 23 connected to the processor 22. The processor 12 of at least one of the plurality of transmitting device DTs is configured to perform the first phase precoding using the corresponding multicast precoding matrix, and the data of the first phase precoding has been performed through the plurality of transmissions The at least one of the signal transceivers 11 of the terminal device DT is transmitted to the other transmitting terminal devices DT other than the plurality of transmitting terminal devices DT; and in a second phase, the plurality of processing of the plurality of transmitting terminal devices DT The processor 12 is configured to perform second stage precoding on the data received in the first phase using the corresponding joint precoding matrix, and the data of the second stage precoding has been performed by the plurality of transmitting end devices DT The plurality of signal transceivers 11 are transmitted to a plurality of signal transceivers 21 corresponding to the plurality of receiving end devices DR of the plurality of transmitting end devices DT, and wherein the plurality of processors 12 of the plurality of transmitting end devices DT are configured to be based on The transmitting end device DT calculates the multicast precoding matrix and the joint precoding matrix from the estimated transmission rate or the estimated transmission power of the first phase and the second phase. The detailed description is as follows.

Referring to FIG. 2, the communication period t can be divided into a data-sharing transmission phase of the first phase and a cooperative joint transmission phase of the second phase. In the first stage, the K transmitting end devices DT transmit their own data to other transmitting end devices in turn. As shown in the figure, the transmission of each transmitting end device DT in the first phase occupies η ₁ time respectively. In the second phase, the K transmitting devices DT will jointly transmit their data to all the receiving device DRs corresponding thereto, as shown in the figure, the entire second phase occupation time ratio is η ₂ , and η ₂ 1- Kη ₁ .

Referring to FIG. 3, in the first phase of the communication period t, the data signal to be transmitted by each of the transmitting devices DT k is [ t ] And each of the transmitting device DT k pairs its own data signal [ t ] using a corresponding multicast precoding matrix (multicast precoding matrix) [ t ] Transfer to all other transmitter devices except yourself. The following equation indicates that the transmitting device DT k transmits its own data signal to the transmitting device DT l , and the signal received by the transmitting device DT l :

Where G _{k , l} [ t ] are the channels of the transmitting device DT k to the transmitting device DT l , and [ t ] is a noise whitening (NW) matrix. Secondly, the following equation represents the reachable multicast rate of the transmitting end device DT k , which can be regarded as the estimated transmission rate of each transmitting device DT transmitting its own data to other transmitting devices in the first phase:

among them, Is a conjugate matrix.

Referring to FIG. 4, the K transmitter devices DT jointly transmit data to the corresponding K sink devices DR using a joint precoding matrix. The following equation represents the received signal DR k means received in the second stage from all the transmitting terminal device DT simultaneously to:

among them, [ t ] is the data signal that the transmitting device DT k needs to transmit in the second phase, [ t ] for correspondence [ t ] Joint precoding matrix.

Then, according to block diagonalization (BD) precoding, the following formula needs to be satisfied: among them, [ t ] forms a null space of the interference channel. In addition, according to the BD precoding, the interference received by the receiving device DR can be ignored. Therefore, the reachable receiving rate of the receiving device DR k can be expressed by the following equation, which can be regarded as each receiving device DR in the second phase. Estimated transmission rate of received data:

among them, It is the equivalent channel of the receiving device DR k .

Therefore, to summarize both the first phase and the second phase, that is, in the communication period t, the overall rate of the kth pair of D2Ds can be expressed by the following equation:

This is the reachable (or estimated transmission) rate of the transmitting device DT k and the receiving device DR k under the cooperative communication method described above.

Furthermore, the power of the transmitting device DT k can be expressed by the following equation:

Where Θ _k is a block diagonalization matrix, and the kth block is an N _t × N _t unit matrix and the other elements are zero.

Next, the following conditions must be considered. The following formulas are represented from top to bottom: long-term utility maximization, long-term power constraint, cooperative rate-gain. Constraint), interference constraint (ie, interference to the base station BS), and the conjugate matrix is a semi-positive semidefinite matrix.

It should be noted that long-term efficiency The sum of the average transmission rates that can be D2D devices or proportional to the proportional fairness. In addition, the long-term power limitation is based on the long-term average power consumption of the cooperative communication is less than or equal to a power consumption threshold. The cooperative rate gain limit is based on the long-term transmission rate of the cooperative communication being greater than or equal to the long-term average transmission rate of a non-cooperative communication. The interference limitation is based on the interference received by a base station being less than or equal to an interference threshold.

It can be seen that the above formulas consider the two factors of the first and second phases, that is, the multicast precoding matrix and the joint precoding matrix of the present case are based on the transmission performance of the first phase and the second phase simultaneously. Designed together.

Figure 5 shows a schematic diagram of the calculation of the above formula. As can be seen from Fig. 5, the above-mentioned long-term efficiency and various limitations can be disassembled into a simplified design of a single communication period and a single device separation operation by the construction of the virtual queue. In Fig. 5, each dotted line frame 51 is a communication period t, and each solid line frame 52 in the broken line frame 51 is a transmitting end device DT, and the arrow 53 indicates that the current calculation is based on the previous calculation result, that is, the current 伫The column state needs to use the state of the virtual data queue, the rate gain queue, and the energy queue 54 of the previous period.

Referring to FIGS. 6A, 6B, and 6C, the virtual queue includes, for example, a virtual data queue D _k [ t ], a rate gain queue O _k [ t ], and an energy queue E _k [ t ]. As shown in Fig. 6A, the input is the virtual arrival procedure A _k [ t ], the output is the reachable rate R _k [ t ], and the virtual data queue of the communication period t+1 can be expressed as follows: D [ t +1] =( D [ t ]- R [ t ]) ⁺ + A [ t ]

As shown in FIG. 6B, the input is the reachable rate of the direct transmission of the transmitting device DT k to the receiving device DR k (that is, direct direct transmission of the point-to-point without using cooperative communication) [ t ], the output is the reachable rate R _k [ t ] of the aforementioned cooperative communication system, and the rate gain queue of the communication period t+1 can be expressed by the following formula: O [ t +1]=( O [ t ]- R [ t ]) ⁺ + R ^{( NC )} [ t ]

As shown in Figure 6C, the input is the power P _k [ t ] and the output is the long-term power limit. The energy queue of the communication period t+1 can be expressed by the following formula.

For detailed calculation, please refer to Figure 7. First, enter the virtual data queue D _k [ t ], the rate gain queue O _k [ t ], and the energy queue E _k [ t ]. It should be noted that each communication period t has the current queue states D _k [ t ], O _k [ t ], and E _k [ t ]. Then it proceeds to step S71.

In step S71, the power balance coefficient δ _{k is} initialized according to the current queue states D _k [ t ], O _k [ t ], and E _k [ t ], and the coefficient can be used to adjust the transmission power and the interference to the base station; Then it proceeds to step S72.

In step S72, the rate balancing coefficient μ _{k is} initialized according to the current queue states D _k [ t ], O _k [ t ], and E _k [ t ], and the coefficient can be used to adjust the allocation of the two-phase transmission rate; Proceed to step S73.

In step S73, the calculated rate of the second stage and the precoding matrix, i.e., the receiving apparatus estimates the transmission rate of the terminal DR k [ t ] and the conjugate matrix associated with the joint precoding matrix [ t ] [ t ]; Then proceed to step S74.

In step S74, the rate and precoding matrix of the first phase, that is, the estimated transmission rate of the transmitting device DT k is calculated. [ t ] and with the multicast precoding matrix [t] related conjugate matrix [ t ]; Then proceed to step S75.

In step S75, the rate balance coefficient μ _{k is} updated. If the rate balance coefficient μ _k converges, it proceeds to step S76; otherwise, it returns to step S73.

In step S76, the power balance coefficient δ _{k is} updated. If the power balance coefficient δk converges, it proceeds to step S77; otherwise, it returns to step S72.

In step S77, the first stage and the group precoding matrix are completed. [t] related conjugate matrix [ t ] and the second stage of the joint precoding matrix [ t ] related conjugate matrix [ t ]. Finally, the output conjugate matrix [ t ] and [ t ].

In the above flow, when the power balance coefficient δ _{k is} fixed, the rate balance coefficient μ _k can be obtained by a bisection algorithm to enable the two stages of the rate to be balanced. When the rate balance factor μ _k converges, the power balance coefficient δ _k can be updated by the averaging algorithm to balance the interference of the allocation to the base station.

The exemplary calculation method of the precoding matrix of the present invention has been described above with reference to the drawings, and then the cooperative communication method of the plurality of transmitting end devices and the plurality of receiving end devices of the present invention will be described with reference to FIG. First, the case divides a communication period into a first phase A and a second phase B. The first phase A is the data sharing transmission phase and the second phase B is the cooperative joint transmission. In the first phase, a plurality of transmitting devices transmit their own data to other transmitting devices in turn, and each of the transmitting devices transmits a time of η ₁ in the first phase; in the second phase, A plurality of transmitting devices jointly transmit their data to all corresponding receiving devices, and the entire second phase occupancy time ratio is η ₂ .

In the first phase A, one of the plurality of transmitting devices transmits the data to the other transmitting device other than itself using the corresponding multicast precoding matrix. That is, after a transmitting end device performs steps S81 and S82, steps S81 and S82 are executed by the next transmitting device until all the transmitting devices transmit their respective data to other transmitting devices. In step S81, a transmitting device performs the first stage precoding using the corresponding multicast precoding, and then proceeds to step S82; in step S82, the transmitting device performs the first stage precoding data. Transfer to a transmitting device other than itself.

In the second phase B, the plurality of transmitting devices transmit the data received in the first phase to the corresponding plurality of receiving devices by using the corresponding joint precoding matrix. That is, in the second stage, each transmitting device has data from other transmitting devices in the first stage in addition to a part of the respective data. In addition, each of the transmitting devices performs steps S83 and S84 simultaneously in the second phase, unlike in the first phase, which needs to be executed in turn. In step S83, the plurality of transmitting end devices perform second stage precoding on the data received in the first stage by using the corresponding joint precoding matrix, and then proceed to step S84; in step S84, the plurality of transmitting The end device transmits the data that has performed the second stage precoding to the corresponding plurality of receiving end devices.

It should be noted that the multicast precoding matrix used in the first phase and the joint precoding matrix used in the second phase are based on the estimated rate and estimated power of the first and second phases, plus the long-term efficiency maximization. , long-term power limitation, cooperative rate gain limitation, and interference (interference to the base station) are limited, and consider the rate and power of the two phases of balanced distribution, and construct the virtual data queue, the rate gain queue, and the energy queue to be based on the previous one. The state of the time period is used to calculate the state of the current time period.

In summary, the cooperative communication method and system applied to multiple transmitting end devices and corresponding multiple receiving end devices in the present invention can improve the received signal quality of the receiving end device and reduce the interference between the transmitting end devices.

The above-described embodiments are merely illustrative of the effects of the present invention, and are not intended to limit the scope of the present invention, and those skilled in the art can modify and modify the above-described embodiments without departing from the spirit and scope of the present invention. Moreover, the number of structures in the above-described embodiments is merely illustrative and is not intended to limit the present invention. Therefore, the scope of protection of the rights in this case should be listed in the scope of the patent application mentioned later.

Claims (16)

 A cooperative communication method for a plurality of transmitting end devices and a plurality of receiving end devices respectively corresponding to the plurality of transmitting end devices, the cooperative communication method comprising: in the first phase, at least one of the plurality of transmitting end devices Performing the first stage precoding by using the corresponding multicast precoding matrix, and transmitting the data of the first stage precoding to the other transmitting device other than itself; In the second phase, the plurality of transmitting devices perform the second-stage precoding on the data received in the first phase by using the corresponding joint precoding matrix, and transmit the data that has been subjected to the second phase precoding to Corresponding to the plurality of receiving end devices of the plurality of transmitting end devices; wherein the calculation of the multicast precoding matrix and the joint precoding matrix is performed according to the plurality of transmitting end devices in the first phase and the second phase Estimated transmission rate or estimated transmission power.    The cooperative communication method according to claim 1, wherein the multicast precoding matrix and the calculation of the joint precoding matrix are based on maximizing long-term efficiency of the plurality of transmitting devices and the plurality of receiving devices .    The cooperative communication method according to claim 2, wherein the long-term efficiency of maximizing long-term efficiency is based on a sum or proportional of an average transmission rate of the plurality of transmitting devices and the plurality of receiving devices .    The cooperative communication method according to claim 1, wherein the multicast precoding matrix and the calculation of the joint precoding matrix are further based on at least one of a long-term power limitation, a cooperative rate gain limitation, and an interference limitation. .    The cooperative communication method according to claim 4, wherein the long-term power limitation is based on a long-term average power in the cooperative communication method is less than or equal to a power consumption threshold, and the cooperation rate gain limitation is based on the cooperation. The long-term average transmission rate in the communication method is greater than or equal to the long-term average transmission rate of a non-cooperative communication method, and the interference limitation is based on the interference of a base station receiving signal being less than or equal to an interference threshold.    The cooperative communication method according to claim 1, wherein the multicast precoding matrix and the calculation of the joint precoding matrix are further based on virtual data queues and rate gains of each of the plurality of transmitting devices. At least one of a column and an energy queue.    For example, the cooperative communication method described in claim 1 of the patent scope further includes: balancing the power of the first phase and the second phase.    For example, the cooperative communication method described in claim 1 of the patent scope further includes: balancing the rate of the first phase and the second phase.    A cooperative communication system includes: a plurality of transmitting end devices each including a signal transceiver and a processor; and a plurality of receiving end devices respectively corresponding to the plurality of transmitting end devices, and Each of the plurality of receiving devices includes a signal transceiver and a processor, wherein in a first phase, a processor of at least one of the plurality of transmitting devices is configured to utilize the corresponding group of data The broadcast precoding matrix performs the first stage precoding, and the data that has been subjected to the first stage precoding is transmitted to the plurality of transmitting end devices via the at least one of the plurality of transmitting end devices And other transmitting end devices; and in a second phase, the plurality of processors of the plurality of transmitting end devices are configured to perform the first use of the corresponding joint precoding matrix for the data received in the first phase Two-stage precoding, and the data that has been subjected to the second stage precoding is transmitted to the plurality of transmitting end devices corresponding to the plurality of transmitting end devices by the plurality of signal transceivers of the plurality of transmitting end devices Receiver devices, and wherein the plurality of processors of the plurality of transmitter devices are configured to determine an estimated transmission rate or an estimated transmission power of the plurality of transmitter devices in the first phase and the second phase The multicast precoding matrix and the joint precoding matrix are calculated.    The cooperative communication system of claim 9, wherein the plurality of processors of the plurality of transmitting devices are configured to maximize long-term efficiency according to the plurality of transmitting devices and the plurality of receiving devices The multicast precoding matrix and the joint precoding matrix are calculated.    The cooperative communication system of claim 10, wherein the plurality of processors of the plurality of transmitting devices are configured to be based on an average transmission rate of the plurality of transmitting devices and the plurality of receiving devices The sum is proportional to the fairness of distribution to calculate long-term efficiency.    The cooperative communication system of claim 9, wherein the plurality of processors of the plurality of transmitting devices are configured to calculate according to at least one of a long-term power limitation, a cooperative rate gain limit, and an interference limit. The multicast precoding matrix and the joint precoding matrix.    The cooperative communication system of claim 12, wherein the plurality of processors of the plurality of transmitting devices are configured to be less than or equal to a power consumption threshold based on a long-term average power in the cooperative communication system. To limit long-term power, the plurality of processors of the plurality of transmitting devices are configured to limit the cooperation rate based on a long-term average transmission rate in the cooperative communication system that is greater than or equal to a long-term average transmission rate in a non-cooperative communication system. Gain, the plurality of processors of the plurality of transmitting end devices are configured to limit interference based on interference to a received signal from a base station being less than or equal to an interference threshold.    The cooperative communication system of claim 9, wherein the plurality of processors of the plurality of transmitting devices are configured to perform virtual data queues, rate gain queues, and At least one of the energy queues calculates the multicast precoding matrix and the joint precoding matrix.    The cooperative communication system of claim 9, wherein the plurality of processors of the plurality of transmitting devices are configured to balance power allocated to the first phase and the second phase.    The cooperative communication system of claim 9, wherein the plurality of processors of the plurality of transmitting devices are configured to balance the rates allocated to the first phase and the second phase.