CN100546403C - Resource allocation and scheduling method for cellular communication system - Google Patents

Abstract

A resource allocation and scheduling method for a cellular communication system, which can avoid interference between cells. The method includes dividing the frequency band of the system into frames, each frame having a preferred allocation block and a general allocation block on the time axis; classifying the terminals in each cell into an interference-sensitive terminal group and an interference-insensitive terminal group the terminal group; and the resource is allocated by the terminal group according to the priority order assigned to the terminal group. The preferred allocated resources designed to be orthogonal to interfering cells, ie sectors, on the time axis are allocated to interference-sensitive terminals, and the remaining resources are allocated to interference-insensitive terminals.

Description

Resource allocation and scheduling method for cellular communication system

technical field

The present invention generally relates to a cellular communication system, and in particular to a method for resource allocation and scheduling of a cellular communication system, by preferentially allocating resources with orthogonality on the time axis to cells with high interference between cells Sensitive terminals can avoid interference between cells.

Background technique

With the development of wireless communication, various services based on broadband communication, such as video conferencing and high-speed Internet access services, have been provided. Due to the advancement of communication technologies, almost unlimited communication environments have been provided. However, wireless access based communication systems have very low throughput and are greatly affected by terminal mobility. Furthermore, the system capacity in a cellular system is limited by interference between cells, and due to the carrier-to-interference (C/I) ratio between adjacent cells, the system capacity is significantly reduced.

Generally, in a cellular system, each cell is divided into several sectors and resources are allocated by sectors, so that the signal-to-interference ratio can be slightly lowered. However, in order to obtain high-band efficiency for supporting high-speed services, a technique that can minimize interference between cells via transmission scheduling and precise resource allocation in addition to dividing cells into sectors is required .

Contents of the invention

Accordingly, the present invention has been designed to solve the above-mentioned and other problems that arise in the prior art. An object of the present invention is to provide a resource allocation and scheduling method for a cellular communication system, which can obtain high frequency band efficiency by increasing frequency reuse rate through precise frame design.

Another object of the present invention is to provide a resource allocation and scheduling method for a cellular communication system, which can obtain high frequency band efficiency and reduce the complexity of frequency design through the frame design of the wireless data cellular network.

Another object of the present invention is to provide a resource allocation and scheduling method for a cellular communication system, which can avoid interference between cells by allocating resources with orthogonality on the time axis to interference-sensitive terminals.

Another object of the present invention is to provide a resource allocation and scheduling method for a cellular communication system, which can minimize the probability of interference by allocating transmit power differently for different time periods on the time axis relative to the terminal, so The terminal is insensitive to interference in neighboring cells, ie sectors, using the same frequency resources.

In order to achieve the above and other objects, a resource allocation scheduling method for a cellular communication system is provided, wherein the frequency reuse rate is at least "1". The method comprises the steps of: dividing the frequency band of the system into frames, each frame having a preferred allocation block and a general allocation block on the time axis; An insensitive terminal group; assigning resources to the interference-sensitive terminal group and the interference-insensitive terminal group according to the priority order given to the interference-sensitive terminal group and the interference-insensitive terminal group, wherein the step of allocating resources includes The following steps: determine whether there is a terminal sensitive to interference; if there is a terminal sensitive to interference, allocate the resources of the preferred allocation block to the terminal sensitive to interference; determine whether the resources of the preferred allocation block remain; if the preferred allocation If the resources of the preferred allocation block are remaining, allocate the remaining resources of the preferred allocation block to the terminals that are not sensitive to interference; and if the resources of the preferred allocation block are not remaining, allocate the resources of the general allocation block to the terminals that are not sensitive to interference .

According to another aspect of the present invention, there is provided a resource allocation and scheduling method for a cellular communication system, which provides communication via a system frequency band assigned to a plurality of base station transceiver subsystems connected through a wired network and a terminal located in a cell Business, the cell is the wireless area of the corresponding base station transceiver subsystem, the method includes the steps of: dividing the corresponding cell into at least two sectors; dividing the frequency band into frames, each of which has a specified time axis period; each of the frames is divided into sub-bands, the number of which is equal to the number of sectors on the frequency axis; each sub-band is divided into a preferred allocation area and a standard allocation area, and the preferred allocation area is arranged and standard allocation areas, so that the preferred allocation areas of the same sub-band allocated to sectors of different cells do not overlap with each other; All terminals in are classified into an interference-sensitive terminal group and an interference-insensitive terminal group; and a preferred allocation area is allocated to interference-sensitive terminals, wherein the transmit power of all terminals in the corresponding cell is according to the Interference sensitivity is controlled.

Description of drawings

The above-mentioned and other objects, characteristics and advantages of the present invention will become clearer by describing preferred embodiments of the present invention in detail in conjunction with the accompanying drawings, wherein:

FIG. 1 is a conceptual diagram illustrating a cellular system including a hexagonal cell to which the present invention is applied;

FIG. 2 is a conceptual diagram illustrating resource usage types in a resource allocation and scheduling method according to a preferred embodiment of the present invention;

Fig. 3 illustrates according to another embodiment of the present invention, applies the inner area of the cell of transmit power control in the resource allocation scheduling method; And

FIG. 4 illustrates resource usage types in a resource allocation scheduling method according to another embodiment of the present invention.

Detailed ways

Several preferred embodiments of the present invention will be described below by means of the accompanying drawings. In the following description, well-known functions or constructions will not be described in detail since they would obscure the subject matter of the present invention in unnecessary detail.

Figure 1 illustrates a cellular system comprising hexagonal cells to which the invention is applied. Referring to FIG. 1, each cell is divided into three sectors. All cells are allocated the same frequency band, and the sectors 101, 102, and 103 constituting the cell 100 are allocated different resources. In addition, the corresponding sector in the cell is designed to be allocated resources different from the adjacent sectors of the adjacent cells. In the present invention, a sector using the same frequency in different cells is referred to as an "interfering sector". In FIG. 1 , the interfering sectors of sector 101 of cell 100 are sector 111 of adjacent cell 110 and sector 121 of another adjacent cell 120 .

For high-band efficiency and low complexity of frequency band design, excessive frequencies are required to be reused for developing wireless cellular systems. Because adjacent cells (ie, sectors) can transmit data simultaneously, the signal-to-interference (C/I) margin is very small, which is a disadvantage of excessive frequency reuse. Interference caused by adjacent sectors can be minimized by coordinating transmissions from sectors that cause interference through precise scheduling in the Base Transceiver Subsystem (BTS).

In a multiple-input multiple-output (MIMO) system, the interference from neighboring cells is not ranked, like a single antenna system. Soft scheduling tunes the matrix interference from adjacent sectors, especially, enough C/I margin for transmission to the terminal in the cell boundary area can be obtained.

Fig. 2 illustrates a resource allocation scheduling method in multiple sectors using the same frequency band in a cellular communication system according to a preferred embodiment of the present invention. In the embodiment of the present invention, although the frame is designed based on time division multiplexing, the present invention is not limited thereto, but may be designed based on various systems, such as frequency division, space division, code division and so on.

Referring to FIG. 2, the frame is divided into 10 slots on the time axis. Here, for convenience of explanation, 10 slots are exemplified, but the number of divided slots may be changed.

The time slot #0 of the system resource is allocated for one control signal, such as Mobile Application Part (MAP), Cell Identifier (CID), etc., and the remaining time slots #1 to #9 are allocated for data transmission . The data area of the corresponding sub-band is divided into blocks 201, 202, and 203, the number of which is equal to the number of sectors in one cell on the time axis. In this embodiment of the present invention, since the data area includes 9 time slots, and each cell is divided into three sectors, three blocks of the corresponding sub-band constitute one block. Accordingly, the corresponding sub-band has three blocks, each of which includes three time slots for data and one time slot for the control signal shared by the three blocks.

The interfering sectors 101, 111, and 121 using the same frequency band set one of the three blocks constituting the corresponding sub-band as the preferred allocation blocks 200-1, 200-2, and 200-3, and arrange the interfering sector The preferred assignment of blocks 200-1, 200-2, and 200-3 of 101, 111, and 121 is such that they do not overlap each other on the time axis.

In this embodiment of the present invention, for the convenience of explanation, the preferred allocation blocks 200-1, 200-2 and 200-3 of interfering sectors 101, 111 and 121 using the same frequency band are sequentially arranged on the time axis above, but the order of arrangement can be changed.

Using frames as described above, interference-sensitive terminals are allocated time slots included in preferred allocation blocks. Terminals located in different interfering sectors and allocated time slots in the preferred allocation block do not interfere with each other because the allocated time slots are orthogonal in time. Through such interference avoidance, efficient frequency reuse becomes possible.

In order to implement the scheduling method according to the present invention, it is necessary to consider detection and feedback of terminal interference, acknowledgment of interference-sensitive terminals, and interference-sensitive scheduling in corresponding BTSs.

Transmission scheduling is performed between synchronized sectors, and the scheduler (not illustrated) of the corresponding interfering sector first allocates the resources of the preferred allocation block and then randomly allocates the remaining resources. Through such scheduling, the probability of occurrence of interference can be reduced. That is, if the traffic load is small, interference from other dominant interfering sectors is avoided, and if the traffic load is large, the average C/I ratio is improved.

According to the scheduling method of the present invention, the corresponding sectors are divided into inner and outer areas of a concentric circle around the BTS, and the transmission power of the terminal is controlled in the inner area, so that improvement of the performance of the system can be expected.

FIG. 3 illustrates an inner region of a cell to which transmission power control is applied in a resource allocation scheduling method according to a preferred embodiment of the present invention. Referring to FIG. 3, in each sector cell 100, a virtual inner area 303 is provided around the BTS. Therefore, in the inner area 303 of the corresponding sector, even if the traffic load of the dominant interfering sector is huge or data is transmitted using the entire frame, a high C/I margin can be guaranteed. This area is the cell area with the least sensitivity to interference.

According to the channel state in the inner area 303 of the sector and the position of the terminal, when the signal arrives at the terminal, the temporary attenuation caused by the signal transmitted from the interfering sector and the sector BTS is very different among the terminals of.

Conversely, if all BTSs continuously transmit with the same power, the average C/I ratio of terminals located close to the BTSs will be much larger than the average C/I ratio of terminals located on the sector border. Assuming that the corresponding terminal continuously performs channel measurements, the scheduler can classify the terminal based on interference sensitivity. Additionally, the terminal can support power control of the BTS by measuring changes in interference power received from neighboring sectors.

Terminals that are more sensitive to interference are only scheduled in the preferred allocation block, and terminals less sensitive to interference are scheduled in the normal data block if the resources of the preferred allocation block are exhausted.

Furthermore, the C/I ratio must be balanced across all sectors. In the current system, the C/I ratio is increased in the inner area of the cell, but the C/I ratio in the cell border area limits the performance of the system, so the peak C/I ratio is lowered.

In addition, the interference susceptibility of terminals can be classified by interfering sectors. Via this classification, temporal orthogonality between a pair of interfering sectors in the frame can be confirmed.

FIG. 4 illustrates transmission power control in a resource allocation scheduling method according to another embodiment of the present invention. Referring to FIG. 4 , the frame is divided into an orthogonal allocation region 410 and a power control region 420 . Relative to terminals with high interference susceptibility, corresponding interfering sectors are preferentially assigned preferred allocation blocks or time slots 410-1, 410-2, and 410-3 of orthogonal allocation area 410, while terminals with low interference susceptibility For a permanent terminal, the interfering sector assigns the power control area 420 to the same time period with different transmit powers by cells or sectors. Therefore, interference between sectors using the same frequency can be minimized.

More specifically, the interfering sectors 101, 111, and 121 of FIG. 1 are assigned different maximum transmit powers of 0.75, 0.25, and 0.25 with respect to time slot #4 421 and time slot #5 422 of the power control region 420, respectively, relative to the time slot #6 and slot #7 are assigned maximum transmit powers of 0.25, 0.75, and 0.25, and relative to slot #8 and slot #9 are allocated maximum transmit powers of 0.25, 0.25, and 0.75, so that the interference between sectors can is relieved.

In the present invention, relative to the three sequential time blocks 420-1, 420-2 and 420-3 of the power control region 420, the interfering sector #1101 is assigned maximum transmission powers of 0.75, 0.25 and 0.25, The interfering sector #2111 is allocated maximum transmit power of 0.25, 0.75 and 0.25, and the interfering sector #3121 is allocated maximum transmit power of 0.25, 0.25 and 0.75.

However, the order and level of transmission power allocated to the time blocks are not limited thereto, but may be changed according to changes in the system environment. Also, in the embodiment of the present invention, it is assumed that the number of slots in a corresponding time block is two. However, the number of time slots is not limited thereto but can be changed according to the system.

Scheduling in MIMO cellular systems

In the following, a scheduling method according to the present invention will be explained, which is conceptualized by applying the method to a MIMO cellular system.

With respect to a given reuse pattern, assume that I is a group of BTSs using the same frequency, and J is a group of terminals in the system. Since the corresponding terminal (j ∈ J) is related to its master BTS (i ∈ I), the average C/I ratio of the link between i and j is the largest among all BTSs. Assuming that multiple access is divided in time and all BTSs are synchronized with each other, the slot period is τ _slot seconds, and N slots constitute a frame. The scheduler calculates the resource allocation of the corresponding sector for each frame period or τ _slot period.

A plurality of BTSs communicate with each other via a wired network, and receive feedback of control signals from corresponding terminals. Each BTS includes a scheduler.

Basically, the terminal has an interference detection device, and via this interference detection function, interference parameters (such as, such as C/I ratio, SINR, interference covariance, channel of the corresponding BTS, etc.) are measured, and the interference is determined sensitivity. The terminal quantifies and feeds back the measured information to the current BTS. The BTS determines whether the terminal belongs to a group sensitive to interference, divides the terminal into two groups according to the sensitivity of the terminal to interference, and then performs scheduling. Time/frequency/space/code slots with better interference characteristics are evenly allocated to interference-sensitive terminals.

These resources can be allocated directly to other BTSs without coordination, or can be allocated to other BTSs with the help of coordination using the backhaul network connecting the BTS. In order to transmit interference information from a terminal to a BTS, a reverse logical channel is used, and in order to transmit the operation result of the scheduler to all terminals, a forward logical channel is used.

Interference sensitivity

A time-space MIMO channel between a pair of BTSs and a terminal is inherent, and the interference susceptibility of the corresponding terminal to all interfering BTSs is calculated and classified. This classification refers to the time-space variance function of the interfering BTS with respect to the terminal, and is changed when the channel conditions between the corresponding terminal and the interfering BTS vary.

Power Control

The BTS transmits signals at a predetermined power level to corresponding terminals located in the sector. If the transmit power level is high, the average interference from adjacent sectors becomes larger. If multi-cell coordination via the wired network is possible, or scheduling is integrated on the Radio Network Controller (RNC), the BTS scheduler can optimize the transmission covariance and transmit power control for multiple BTSs.

slot allocation

Interference avoidance is possible by allocating orthogonal time slots to adjacent sectors. If the same time slot is allocated, interference occurs proportional to the interference susceptibility of the terminal to the interfering BTS and the transmit power used by the neighboring BTS for transmission.

As described above, according to the scheduling method of the present invention, blind coordination between adjacent sectors becomes possible. It is conceivable that the corresponding terminal measures the C/I ratio for the master BTS and all interfering sectors. By reducing the BTS transmit power level for a portion of the time slot, interference-sensitive terminals can obtain an improved C/I ratio. The BTS transmit power level for a slot cycle compensates for the interference susceptibility of the terminals to which the corresponding slot has been allocated. The time slots of the corresponding frames may be allocated to the three sectors with a variance, and in this case no overlapping transmissions occur.

The scheduling method according to the present invention can be combined with capacity maximization schemes such as precoding for MIMO systems to greatly improve system capacity.

In the present invention, a logical control channel is used for sending information about the operation result of the scheduler to the terminal, or sending quantized information from the terminal to the BTS.

As described above, according to the resource allocation and scheduling method of the present invention, by dividing the terminal according to the interference sensitivity, the optimal allocation resources designed to be orthogonal to the interfering cell (ie sector) on the time axis are preferentially allocated to Interference-sensitive terminals, and allocating the remaining resources to interference-insensitive terminals, can avoid interference between cells using the same resources.

In addition, the resource allocation and scheduling method according to the present invention takes into account the transmit power of adjacent cells (that is, sectors) using the same frequency band, and by controlling the transmit power relative to terminals that are not sensitive to interference, it is possible to reduce the relative Probability of occurrence of interference from an interference-insensitive terminal.

Although the invention has been described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that changes may be made in form and form without departing from the spirit and scope of the invention as defined by the appended claims. Various modifications of details.

Claims (12)

1. resource allocation scheduling method that is used for cellular communication system, wherein frequency reuse rates is " 1 " at least, the method comprising the steps of:

With the frequency band division of system is frame, and each frame has preferred allocation block and general allocation block on time shaft;

Terminal is categorized as disturbing responsive set of terminal and to disturbing insensitive set of terminal; With

According to giving to disturbing responsive set of terminal and the priority of disturbing insensitive set of terminal is given disturbing responsive set of terminal and to disturbing insensitive set of terminal to distribute resource,

Wherein, the step of Resources allocation may further comprise the steps:

Determine whether to exist to disturbing responsive terminal;

If exist disturbing responsive terminal, then the resource allocation of preferred allocation block given disturbing responsive terminal;

Whether the resource of determining preferred allocation block remains;

If the resources left of preferred allocation block is then distributed to the surplus resources of preferred allocation block disturbing insensitive terminal; With

If the resource of preferred allocation block is residue not, then the resource allocation of general allocation block is given disturbing insensitive terminal.

2. resource allocation scheduling method according to claim 1, wherein the resource of preferred allocation block is assigned to adjacent sub-district, makes this resource have orthogonality on time shaft.

3. resource allocation scheduling method according to claim 2, the resource of wherein general allocation block are given adjacent sub-district with different transmit power allocations on time shaft.

4. resource allocation scheduling method that is used for cellular communication system, it provides communication service via giving to a plurality of by cable network BTS under CROS environment that connects and the band system band that is arranged in the terminal of sub-district, this sub-district is the wireless zone of relevant base station transceiver subsystem, and the method comprising the steps of:

Corresponding microzonation is divided at least two sectors;

With frequency band division is frame, and each described frame has the cycle of appointment on time shaft;

Each of described frame is divided into sub-band, and its number equals the number of the sector on the frequency axis;

With this sub-band division is the range of distribution of preferred range of distribution and standard;

Arrange the range of distribution of this preferred range of distribution and standard, make the preferred range of distribution of identical sub-band of the sector distribute to different sub-districts not overlap each other;

According to all terminals in corresponding sub-district being categorized as disturbing responsive set of terminal and to disturbing insensitive set of terminal from the susceptibility of the adjacent sectors that uses same sub-band; With

Preferred range of distribution is distributed to disturbing responsive terminal,

The transmitting power of all terminals in the wherein corresponding sub-district is controlled according to described susceptibility.

5. resource allocation scheduling method according to claim 4, wherein this preferred range of distribution is assigned to disturbing responsive terminal, and the range of distribution of this standard is assigned to disturbing insensitive terminal then.

6. resource allocation scheduling method according to claim 4, wherein this frame is divided into a plurality of time slots on time shaft.

7. resource allocation scheduling method according to claim 6, wherein first time slot of this frame comprises a control signal.

8. resource allocation scheduling method according to claim 7, wherein this control signal comprises MAP MAP information.

9. resource allocation scheduling method according to claim 4, wherein this sub-band is divided into a plurality of subchannels on frequency axis.

10. resource allocation scheduling method according to claim 4, if wherein described susceptibility is enhanced, the transmitting power of all terminals in the so corresponding sub-district is enhanced, if and described susceptibility is lowered, the transmitting power of all terminals in the so corresponding sub-district is lowered.

11. resource allocation scheduling method according to claim 4, wherein said susceptibility are to use the channel condition information of the adjacent sectors of being measured by all terminals in the respective cell to calculate, and are fed to this BTS under CROS environment.

12. according to the described resource allocation scheduling method of claim 11, wherein this channel condition information comprises from the Strength Changes amount of the interference signal of adjacent sectors reception.

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