CN102781112B - Method, system and base station for scheduling relay feedback link based on multi-user MIMO (Multiple Input Multiple Output) - Google Patents

Abstract

The present application provides a multi-user MIMO-based relay backhaul link scheduling method, system and base station thereof. The scheduling method includes: determining the active set of relay stations of the base station; determining the priority of each relay station in the active set of relay stations; The correlation between any two relay stations in the scheduling relay stations is smaller than a predetermined correlation threshold. The scheduling method of the present application takes into account not only the priority of the relay station but also the correlation between the relay stations, thereby reducing the inter-flow interference of the system and improving the throughput of the backhaul link.

Description

Relay backhaul link scheduling method, system and base station based on multi-user MIMO

technical field

The present application relates to the field of wireless communication, and more specifically, the present invention relates to a multi-user MIMO (MU-MIMO)-based relay backhaul link scheduling method, system and base station thereof.

Background technique

As an emerging technology, relay technology can increase coverage and system capacity, and is regarded as the key technology of the fourth generation mobile communication (4G). The throughput of the relay system backhaul link (eNB-RN) limits the throughput of the entire system to a certain extent, and becomes the bottleneck of the system throughput. This requires the use of appropriate technologies and scheduling schemes in the backhaul (Backhaul) link to increase the capacity of the backhaul link.

As shown in Figure 1, through the relay backhaul link scheduling scheme based on multi-user MIMO, the base station (eNodeB) can schedule multiple relay stations (RN1, RN2...) on the same time-frequency resource (RB, Resource Block) , thus effectively increasing the capacity of the backhaul link, and solving the bottleneck effect of the backhaul link to a certain extent. However, while obtaining the multiplexing gain, since different relay stations share the same time-frequency resource RB, the inter-flow interference between relay stations limits the improvement of the throughput of the backhaul link. Therefore, under the MU-MIMO scheduling scheme, how to effectively reduce the inter-stream interference under the same time-frequency resource RB becomes the key to improving the throughput of the backhaul link.

In the existing solution, when the base station performs relay backhaul link scheduling, the PF (Proportional Fair) scheduling algorithm is used as an example to calculate the priority of each RN subordinate to the base station, and perform scheduling according to the priority.

This method of scheduling according to the RN priority guarantees the quality of transmission to a certain extent. However, in the scheduling process of the existing scheme, only the priority of the RN is considered, and the correlation between the scheduled RNs is not considered. This may cause greater correlation between RNs scheduled on the same time-frequency resource RB, and correspondingly greater inter-flow interference, which will reduce the receiving signal-to-noise ratio of the RN to a certain extent and increase the risk of data retransmission. possibility, which will affect the capacity of the backhaul link.

Contents of the invention

The purpose of this application is to provide a backhaul link scheduling method, system and base station thereof that can at least partially improve the defects in the above-mentioned prior art, so as to reduce the inter-flow interference of the system and improve the throughput of the backhaul link quantity.

According to one aspect of the present application, a method for scheduling a relay backhaul link based on multi-user MIMO is disclosed, including: determining the relay station active set of the base station; determining the priority of each relay station in the relay station active set; according to the determined Select the schedulable relay stations on the time-frequency resources from the relay station activation set in the priority order of , so that the correlation between any two relay stations in the selected schedulable relay stations is less than a predetermined correlation threshold.

According to another aspect of the present application, a base station for implementing a multi-user MIMO-based relay backhaul link scheduling method is disclosed, including: a determination module for determining the active set of relay stations of the base station; a calculation module for calculating the The priority of each relay station in the relay station activation set; and the scheduling module, which selects the relay stations that can be scheduled on the time-frequency resource from the relay station activation set in the order of priority, so that the correlation between any two relay stations in the selected schedulable relay stations less than the predetermined correlation threshold.

According to another aspect of the present application, a scheduling system for implementing a relay backhaul link based on multi-user MIMO is disclosed, including a base station; and a plurality of relay stations, wherein the base station further includes: a determination module, determining the relay station of the base station An active set; a calculation module, calculating the priority of each relay station in the active set of relay stations; and a scheduling module, selecting relay stations that can be scheduled on time-frequency resources from the active set of relay stations according to the order of priority, so that the relay stations in the selected schedulable relay stations The correlation between any two relay stations is less than a predetermined correlation threshold.

The invention not only considers the priority of the relay station but also considers the correlation between the relay stations, thereby reducing the inter-flow interference of the system and improving the throughput of the return link.

Description of drawings

Fig. 1 shows a structural diagram of a relay system in the prior art.

Fig. 2 shows a flowchart of a scheduling scheme according to an embodiment of the present application.

Fig. 3 shows a schematic diagram of determining the correlation by the horizontal angle formed between the relay station and the base station according to the present application.

Fig. 4 shows a flowchart of a specific scheduling scheme according to an embodiment of the present application.

Fig. 5 shows a block diagram of a scheduling system according to an embodiment of the present application.

Detailed ways

The multi-user MIMO-based relay backhaul link scheduling method disclosed in the present application and its base station will be described in detail below with reference to the accompanying drawings. For the sake of brevity, in the descriptions of the embodiments of the present application, the same or similar devices use the same or similar reference numerals.

Fig. 2 shows a flowchart of a scheduling scheme according to an embodiment of the present application. As shown in the figure, in step 201, an active set of relay stations (RNs) of a base station is determined. Here, the active set of relay stations of the base station refers to the set of RNs waiting to be scheduled in the base station, that is, the set of relay stations excluding all idle or relay stations with retransmission data in the base station.

In step 202, the priority of each relay station in the relay station active set is determined. According to an embodiment, the existing PF scheduling algorithm may be used to calculate the priority of each RN subordinate to the base station. According to another embodiment, when determining the priority of the relay station RN, the priority of each user equipment (UE) of the RN may be calculated, and the highest priority among the UEs of the RN is selected as the priority of the RN.

In step 203, select relay stations that are schedulable on time-frequency resources from the active set of relay stations according to the determined priority order, so that the correlation between any two relay stations in the selected schedulable relay stations is less than a predetermined correlation threshold .

It can be understood that in the MU-MIMO-based backhaul link scheduling method, multiple relay stations (for example, two, three, four or more relay stations) can be scheduled on one time-frequency resource RB. In the prior art, relay stations are only scheduled in order of priority. For example, for the time-frequency resource RB that can schedule two relay stations, the two relay stations with the highest priority are allocated to the time-frequency resource RB; or, for the time-frequency resource RB that can schedule four relay stations, the four relay stations with the highest priority A relay station is allocated to the time-frequency resource RB. However, according to the scheduling method of the present application, when selecting relay stations that can be scheduled on time-frequency resources from the relay station activation set according to the priority order, at the same time, it is required that the correlation between any two relay stations in the selected schedulable relay stations is less than the predetermined correlation sex threshold.

The correlation between relay stations refers to the degree of correlation between two relay stations, usually through the correlation between the channel impulse response vector (in the case of single antenna) or matrix (in the case of multiple antennas) between two relay stations and the base station To represent. Specifically, the correlation x _n,m between relay station RN _n and relay station RN _m can be expressed as

${\mathrm{<span\; class="notranslate">\; \&chi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>}_{\mathrm{<span\; class="notranslate">\; f</span>}}}{{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>}_{\mathrm{<span\; class="notranslate">\; f</span>}}{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>}_{\mathrm{<span\; class="notranslate">\; f</span>}}}$

Wherein, the superscript H represents the conjugate transpose of the matrix, and H _n and H _m respectively represent the channel impulse response vector or matrix between the relay stations RN _n and RN _m and the base station.

However, it can be understood that the algorithm for calculating the correlation between two relay stations using the above formula is relatively complicated. For this reason, the present application further proposes a method for expressing relay station correlation by angle, which reduces calculation complexity and improves calculation efficiency.

In addition, due to the large radial distance between the relay station and the base station, the correlation between the relay stations is greatly affected by the horizontal angle formed between the relay station and the base station (wherein, the horizontal angle refers to the angle formed between the relay station and the base station Horizontal projection angle), and the influence by the pitch angle (vertical projection angle of the angle formed between the relay station and the base station) is almost negligible. That is to say, in the relay system, the correlation between two relay stations can be determined by the horizontal angle formed between the two relay stations and the base station, and the larger the horizontal angle formed between the two relay stations and the base station , the correlation between two relay stations is relatively smaller.

The following provides a theoretical proof that the angle between the relay station and the base station can represent the correlation between the relay stations.

In a relay system, generally there is a direct path (LoS) between the relay station and the base station. In the LoS scenario, the power of the direct path is generally stronger than that of the indirect path, and the channel impulse response of the direct path plays a decisive role in the channel matrix. The channel impulse response generation process of the direct path is as follows:

Among them, the subscripts u, s and n represent the numbers of the receiving end, the sending end and the multipath respectively. K _R represents the Rice K factor, d _s represents the distance between the antennas at the transmitting end, d _u represents the distance between the antennas at the receiving end, λ ₀ represents the wavelength corresponding to the carrier frequency, Indicates the angle of arrival of the signal at the receiving end, φ _LOS indicates the departure angle of the signal at the transmitting end, F _{rx, u, V} (□) and F _{rx, u, H} (□) represent the vertical and horizontal antennas of the receiving end, respectively gain. F _{tx, u, V} (□) and F _{tx, u, H} (□) represent the antenna gain of the transmitting end in the vertical direction and the horizontal direction, respectively.

This part is related to the horizontal, vertical orientation and polarization direction of the transceiver antenna, and plays a random effect in the generation of channel impulse response. in is the initial phase angle of the LoS path in the vertical polarization direction, is the initial phase angle of the LoS path in the horizontal polarization direction.

in the formula These two parts are the phase difference between the sending end and the receiving end, and exp(j2πv _LOS t) is the influence of moving speed and direction on the phase.

Although the time delay of the channel impulse response of each path of each user is independently and randomly generated, the impulse responses of the channel matrix used for SVD decomposition in practice are combined, and the direct path The channel impulse responses are generally combined in the first row of the channel matrix:

In the formula, a _{w, i} represent the impulse response of the non-direct path.

Since the mean value of K _R is 9dB, generally |b| ² ＞＞|a _{w, i} | ² . The beamforming vector obtained from this decomposition:

$\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; \&ap;</span>{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; LOS</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\sqrt{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; LOS</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\sqrt{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; T</span>}}$

The problem we care about is the relationship between the interference of the current service user to the interfered user and the angle between them. For the convenience of discussion, let φ _LOS =0, then φ′ _LOS can represent the angle between the current serving user and the interfered user, that is, the horizontal angle formed between two relay stations and the base station. at this time:

$\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; \&ap;</span>{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\sqrt{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\sqrt{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; T</span>}}$

${\mathrm{<span\; class="notranslate">\; h</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 8</span>}}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 8</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 8</span>}}}\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 7</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; LOS</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\\ \frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 8</span>}}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 8</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\end{array}\right]$

Since a′ _{w, i} represent the impulse response of the indirect path, the interference caused by the current serving user to the interfered user can be approximated:

${<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\mathrm{<span\; class="notranslate">\; w</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&ap;</span>\frac{{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; b</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 8</span>}}{<span\; class="notranslate">\; |</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 7</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; LOS</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$

Since when scheduling relay stations, the same time-frequency resource usually only involves the scheduling of relay stations in the same cell, considering the distribution of relay stations and the symmetry of sectors, we can set the value range of φ′ _LOS as 0-70 degrees. We might as well assume that |b′| ² =1. At this time, as the φ′ _LOS angle increases, the interference caused by the current serving user to the interfered user will gradually decrease and the effect will be obvious.

It can be seen from the above proof that since the signal transmission between the base station and the relay station generally meets the conditions of the LoS scenario, when the base station serves two relay stations at the same time, the larger the horizontal angle between the two relay stations and the base station, the greater the distance between the relay stations. less distraction. This conclusion can be extended to the scenario where the base station serves multiple relay stations at the same time.

According to an implementation manner, the angular position relationship between each relay station and the base station is pre-stored in the base station. In this way, the horizontal angle formed between any two relay stations and the base station can be calculated according to the stored angular position relationship, and the correlation between the two relay stations can be determined.

FIG. 3 shows the horizontal angle of correlation between relay stations by taking the scheme that each sector contains 6 relay stations as an example. In the case of 6 relay stations per sector, the distribution of RNs is shown in FIG. 3 . At this time, the horizontal angle formed by each RN in the sector and the base station is fixed. A Cartesian coordinate system is established with the base station as the origin, as shown in Figure 3. Then, the horizontal angle between RN _n and RN _m to eNode B is

Δθ _n,m = |θ _n -θ _m |

Wherein, θ _n is the horizontal angle between the line connecting RN _n and the base station and the X axis, and θ _m is the horizontal angle between the line connecting RN _m and the base station and the X axis.

In this embodiment, the angular position relationship between each relay station and the base station may be pre-stored in the base station, for example, the horizontal angle between the connection line between each relay station and the base station and the X axis. Therefore, the base station can calculate the horizontal angle formed between any two relay stations and the base station according to the stored angular position relationship, so as to determine the correlation between the two relay stations.

As mentioned above, the larger the horizontal angle formed between the relay station and the base station, the smaller the correlation between users, that is, the larger the horizontal angle Δθ _n,m between RN _n and RN _m , the larger the RN _n and The correlation between RN _m is relatively smaller.

Based on this, according to an embodiment of the present application, the correlation between two relay stations is represented by the horizontal angle formed between the two relay stations and the base station, and any two relay stations in the selected schedulable relay stations are required to The correlation between is less than the predetermined angle threshold θ _min , when the horizontal angle Δθ _{n, m} between RN _n and RN _m satisfies the following relationship, RN _m is a schedulable relay station:

Δθ _n,m = |θ _n -θ _m |≥θ _min $\&ForAll;m\&Element;W$

The set W represents a set of schedulable relay stations on a certain time-frequency resource, RN _n represents a scheduled RN in the set W, and RN _m represents a certain RN not scheduled outside the set W. Wherein, the included angle threshold θ _min may be preset according to actual application scenarios. According to an embodiment, for example, the included angle threshold value may be selected between 10-30 degrees, such as 10 degrees, 20 degrees or 30 degrees. The larger the included angle threshold is, the weaker the selection effect on relay correlation is.

According to another embodiment, when a mobile relay station is used, the base station may calculate the angular position relationship between the relay station and the base station. For example, the base station can use the existing beamforming algorithm (such as the GOB algorithm) to calculate the horizontal angle between the connection line between any relay station and the base station and the positive direction of the antenna (such as the X axis shown in Figure 3), so as to further calculate The horizontal angle formed between any two relay stations and the base station determines the correlation between the two relay stations.

Since the complex correlation calculation is simplified to the linear calculation of the horizontal angle between RNs, the complexity of the algorithm is relatively reduced, and the performance of the system scheduling is improved while ensuring the efficiency of the scheduling algorithm.

A method for scheduling a relay backhaul link according to an embodiment of the present invention will be described in detail below with reference to FIG. 4 . According to the method, a scheduling set of time-frequency resource RBs can be established considering the priority and correlation of RNs, so as to select relay stations RNs for data transmission.

In step 401, an active set of relay stations of a base station is determined. Here, the active set of relay stations of the base station refers to the set of relay stations waiting to be scheduled in the base station, that is, the set of all relay stations in the base station excluding those that are idle or have retransmission data.

It can be understood that when scheduling the backhaul link, the RN with retransmission data should transmit the retransmission data preferentially. For example, the base station can judge whether there is retransmission data on the time-frequency resource RB through uplink hybrid automatic repeat request (HARQ) information, and if so, directly schedule the relay station RN and its user equipment corresponding to the retransmission data. Here, the method of judging whether it is idle or has a relay station for retransmitting data belongs to the prior art, and will not be repeated here. For relay stations that are not idle and do not retransmit data, an appropriate scheduling method needs to be used for scheduling, so as to reduce the inter-flow interference of the system and improve the throughput of the backhaul link.

In step 402, the priority of each relay station in the relay station active set is determined. According to an embodiment, the existing PF scheduling algorithm may be used to calculate the priority of each RN subordinate to the base station. According to another embodiment, when determining the priority of a relay station, the priorities of each user equipment of the relay station may be calculated, and the highest priority among the user equipments of the relay station may be selected as the priority of the relay station.

In step 403, the relay station RN with the first priority is selected as the first schedulable relay station on the time-frequency resource RB.

As mentioned above, multiple relay stations RN can be scheduled on one time-frequency resource RB. According to the backhaul link scheduling method of the present application, after the first schedulable relay station of the time-frequency resource RB is determined, other schedulable relay stations can be iteratively selected by considering the priority of each relay station and their mutual correlation.

In step 404, a schedulable relay station that satisfies a correlation condition with the selected schedulable relay station is iteratively selected in descending order of priority.

According to an embodiment, when performing iterative selection, it may first be determined whether the correlation between the relay station of the second priority and the first schedulable relay station is less than a preset correlation threshold, and if it is smaller, the second priority is selected The relay station of is the second schedulable relay station. Otherwise, a relay station whose correlation with the first schedulable relay station is smaller than a preset correlation threshold is selected as the second schedulable relay station in descending order of priority. After that, continue to select the schedulable relay station (for example, the third schedulable relay station) that satisfies the correlation condition among the selected schedulable relay stations (for example, the first and second schedulable relay stations) in order of priority from high to low. Scheduling relay stations) until the number of schedulable relay stations on the time-frequency resource RB reaches the maximum value, that is, the total number of schedulable relay stations that can be supported by one time-frequency resource RB in the system is reached. At this point, the relay station scheduling of one time-frequency resource RB is completed.

If after the iterative selection ends, the number of schedulable relay stations selected that meet the conditions does not reach the maximum number of schedulable relay stations on the time-frequency resource RB, then the correlation between relay stations can be ignored, and according to the relay station activation concentration The priority order of the unselected relay stations is used to select the remaining relay stations on the time-frequency resource RB to complete the relay station scheduling of the time-frequency resource RB.

According to another embodiment, in order to realize the step of iteratively selecting the schedulable relay station that satisfies the correlation condition with the selected schedulable relay station in the order of priority from high to low in the above step 404, it is possible to first calculate the relay station The correlation between the unselected relay stations in the active set and the selected schedulable relay station (eg, the first schedulable relay station selected in step 403 ). Find out all the relay stations that satisfy the correlation condition with the selected schedulable relay stations. The relay station with the highest priority is selected from the set of found relay stations as the second schedulable relay station. Iterate the above calculation, search and selection process in the found set of relay stations until the number of relay stations that can be scheduled on the time-frequency resource RB reaches the maximum value, that is, the total number of relay stations that can be supported on one time-frequency resource RB in the system is reached. The number of schedulable relay stations. At this point, the relay station scheduling of one time-frequency resource RB is completed.

If after the iterative selection ends, the number of schedulable relay stations selected that meet the conditions does not reach the maximum number of schedulable relay stations on the time-frequency resource RB, then the correlation between relay stations can be ignored, and according to the relay station activation concentration The priority order of the unselected relay stations is used to select the remaining relay stations on the time-frequency resource RB to complete the relay station scheduling of the time-frequency resource RB.

According to another aspect of the present application, a scheduling system for implementing multi-user MIMO-based relay backhaul links is disclosed. As shown in FIG. 5 , the scheduling system includes a base station 500 and multiple relay stations 600 . According to the present application, in the scheduling system, the base station 500 can determine the relay station active set in the relay station 600; determine the priority of each relay station in the relay station active set; and select time-frequency resources from the relay station active set according to the determined priority order schedulable relay stations, so that the correlation between any two relay stations in the selected schedulable relay stations is less than a predetermined correlation threshold.

The base station 500 in the scheduling system for implementing multi-user MIMO-based relay backhaul links according to the present application will be further described in detail below. As shown in FIG. 5 , the base station 500 includes a determination module 510 , a calculation module 520 and a scheduling module 530 .

The determination module 510 determines the active set of relay stations of the base station 500 . Here, the active set of relay stations of the base station refers to the set of RNs waiting to be scheduled in the base station, that is, the set of relay stations excluding all idle or relay stations with retransmission data in the base station.

The calculation module 520 calculates the priority of each relay station in the relay station active set. According to an embodiment, the existing PF scheduling algorithm may be used to calculate the priority of each RN subordinate to the base station. According to another embodiment, when determining the priority of the relay station RN, the priority of each user equipment of the RN may be calculated, and the highest priority among the user equipment of the relay station RN is selected as the priority of the RN.

The scheduling module 530 selects a schedulable relay station on the time-frequency resource from the relay station activation set in order of priority, so that the correlation between any two relay stations in the selected schedulable relay stations is less than a predetermined correlation threshold. It can be understood that in the MU-MIMO-based backhaul link scheduling method, multiple relay stations (for example, two, three, four or more relay stations) can be scheduled on one time-frequency resource RB. In the prior art, relay stations are only scheduled in order of priority. However, according to the scheduling method of the present application, when selecting relay stations schedulable on time-frequency resources from the relay station activation set according to priority order, it is also required that the correlation between any two relay stations in the selected schedulable relay stations is less than the predetermined correlation sex threshold.

According to an implementation manner, the scheduling module 530 further includes an angle determination module 531 and a selection module 532 . The angle determination module 531 determines the horizontal angle formed between the relay station and the base station, wherein the correlation between two relay stations is determined by the horizontal angle formed between the two relay stations and the base station, and the predetermined correlation threshold is a predetermined Angle threshold. The selection module 532 selects relay stations that are schedulable on time-frequency resources from the active set of relay stations in the order of priority, so that the horizontal angle formed between any two relay stations among the selected schedulable relay stations and the base station is smaller than a predetermined angle gate limit.

According to another embodiment, the angle determination module 531 pre-stores an angular position relationship table between each relay station in the base station and the base station, and can determine the horizontal angle formed between two relay stations and the base station according to the angular position relationship table.

According to another embodiment, when a mobile relay station is used, the angle determination module 531 calculates the angular position relationship between the relay station and the base station, and determines the horizontal angle formed between the two relay stations and the base station according to the calculated angular position relationship . For example, the base station can use the existing beamforming algorithm (such as the GOB algorithm) to calculate the horizontal angle between the connection line between any relay station and the base station and the positive direction of the antenna, so as to further calculate the horizontal angle between any two relay stations and the base station. angle, to determine the correlation between two relay stations.

According to an embodiment of the present application, the selection module 532 is configured to select the relay station RN with the first priority as the first schedulable relay station on the time-frequency resource RB, and iteratively select the relay station that satisfies the The schedulable relay stations whose correlation among the selected schedulable relay stations is smaller than a predetermined correlation threshold. Optionally, if after the iterative selection ends, the selected number of schedulable relay stations does not reach the maximum number of schedulable relay stations on the time-frequency resource, the selection module 532 can select according to the number of relay stations not selected in the relay station activation set The remaining schedulable relay stations on the time-frequency resources are selected in order of priority.

The exemplary embodiments of the present application are described above with reference to the accompanying drawings. It should be understood by those skilled in the art that the above-mentioned embodiments are only examples for the purpose of illustration, and are not used for limitation. Any modifications, equivalent replacements, etc. All should be included in the protection scope of this application.

Claims (16)

1., based on a dispatching method for the relaying return link of multiuser MIMO, comprising:

Determine the Relay stations activation collection of base station;

Determine that described Relay stations activation concentrates the priority of each relay station; And

From relay station Active Set, select schedulable relay station on running time-frequency resource according to determined priority orders, make the correlation between any two relay stations in selected schedulable relay station be less than pre-determined relevancy threshold.

2. dispatching method according to claim 1, wherein, the correlation between two relay stations is determined by described two horizontal sextant angles formed between relay station and base station.

3. dispatching method according to claim 2, comprises the angular position relative prestoring in a base station and formed between each relay station in described base station and described base station further.

4. dispatching method according to claim 2, comprises the angular position relative calculating and formed between relay station and described base station further.

5. the dispatching method according to any one in claim 1-4, wherein, from relay station Active Set, select schedulable relay station on running time-frequency resource according to determined priority orders, the step making the correlation between any two relay stations in selected schedulable relay station be less than pre-determined relevancy threshold comprises:

Select the relay station of the first priority as the first schedulable relay station on running time-frequency resource; And

The correlation between the schedulable relay station selected is selected to be less than the schedulable relay station of pre-determined relevancy threshold according to priority sequential iteration from high to low.

6. dispatching method according to claim 5, wherein, the step selecting the correlation between the schedulable relay station selected to be less than the schedulable relay station of pre-determined relevancy threshold according to priority sequential iteration from high to low comprises further:

Judge whether the correlation between the relay station of the second priority and the first schedulable relay station is less than pre-determined relevancy threshold;

When the result judged is as being less than default relevance threshold, the relay station of described second priority is selected to be the second schedulable relay station, otherwise, be less than the relay station of pre-determined relevancy threshold as the second schedulable relay station according to the correlation between priority selective sequential from high to low and the first schedulable relay station; And

The above-mentioned judgement of iteration and selection step, until schedulable relay station quantity reaches maximum on described running time-frequency resource.

7. dispatching method according to claim 6, comprises further:

If after iteration selection terminates, selected by the schedulable relay station quantity that goes out when not reaching the maximum of schedulable relay station quantity on described running time-frequency resource, concentrate the priority of non-selected relay station order to select remaining schedulable relay station on described running time-frequency resource according to Relay stations activation.

8. dispatching method according to claim 5, wherein, the step selecting the correlation between the schedulable relay station selected to be less than the schedulable relay station of pre-determined relevancy threshold according to priority sequential iteration from high to low comprises further:

Calculate described Relay stations activation concentrate non-selected relay station and selected go out the first schedulable relay station between correlation;

The correlation found out between all and the first schedulable relay station is less than the relay station of pre-determined relevancy threshold;

In found out relay station, select relay station that priority is the highest as the second schedulable relay station; And

The above-mentioned calculating of iteration, search and select step, until schedulable relay station quantity reaches maximum on described running time-frequency resource.

9. dispatching method according to claim 8, wherein, comprises further:

If after iteration selection terminates, selected by the schedulable relay station quantity that goes out when not reaching the maximum of schedulable relay station quantity on described running time-frequency resource, concentrate the priority of non-selected relay station order to select remaining schedulable relay station on described running time-frequency resource according to Relay stations activation.

10. realize the base station based on the dispatching method of the relaying return link of multiuser MIMO, comprising:

Determination module, determines the Relay stations activation collection of described base station;

Computing module, calculates the priority that described Relay stations activation concentrates each relay station; And

Scheduler module, selects schedulable relay station on running time-frequency resource according to the order of priority from relay station Active Set, makes the correlation between any two relay stations in selected schedulable relay station be less than pre-determined relevancy threshold.

11. base stations according to claim 10, described scheduler module comprises further:

Angle determination module, determines the horizontal sextant angle formed between relay station and base station, and wherein, the correlation between two relay stations is determined by the horizontal sextant angle formed between described two relay stations and described base station; And

Select module, concentrate selection schedulable relay station on running time-frequency resource according to the order of priority from described Relay stations activation, make any two horizontal sextant angles formed between relay station and base station in selected schedulable relay station be less than predetermined angle threshold value.

12. base stations according to claim 11, wherein, described angle determination module is previously stored with the angular position relative table between each relay station in described base station and described base station, and determines the horizontal sextant angle that formed between two relay stations and described base station according to described angular position relative table.

13. base stations according to claim 11, wherein, described angle determination module calculates the angular position relative between relay station and base station, and determines two horizontal sextant angles formed between relay station and base station according to calculated angular position relative.

14. base stations according to any one in claim 10-13, wherein, described selection module is configured to: select the relay station of the first priority as the first schedulable relay station on running time-frequency resource; And select the correlation between the schedulable relay station selected to be less than the schedulable relay station of pre-determined relevancy threshold according to priority sequential iteration from high to low.

15. base stations according to claim 14, wherein, described selection module is configured to: if iteration select terminate after, selected by the schedulable relay station quantity that goes out when not reaching the maximum of schedulable relay station quantity on described running time-frequency resource, concentrate the priority of non-selected relay station order to select remaining schedulable relay station for described running time-frequency resource according to Relay stations activation.

16. 1 kinds of dispatching patchers realized based on the relaying return link of multiuser MIMO, comprise

Base station; And

Multiple relay station, wherein base station comprises further:

Determination module, determines the Relay stations activation collection of described base station;

Computing module, calculates the priority that described Relay stations activation concentrates each relay station; And

Scheduler module, selects schedulable relay station on running time-frequency resource according to the order of priority from relay station Active Set, makes the correlation between any two relay stations in selected schedulable relay station be less than pre-determined relevancy threshold.