KR100866568B1 - Method for allocating resources in wireless multi-hop network - Google Patents

Abstract

In a method for allocating resources in a multi-hop wireless network according to the present invention, a method for allocating radio resources by an apparatus for allocating radio resources in a multi-hop wireless network, comprising: receiving a resource allocation request from an upper node and a lower node; step; Allocating radio resources after constructing a frame according to the request; And reallocating the radio resources so as to minimize co-channel interference (CCI) by monitoring communication channel information between the device and upper and lower nodes. To combine the D-TDD system and multi-hop technology to effectively support the system, and to reduce the performance degradation of the D-TDD system caused by the mismatch of the uplink and downlink interval between the cells constituting the multi-hop wireless network Can be assigned.

Description

Method for allocating resources in wireless multi-hop network

1 is a diagram illustrating a general frame structure of a dynamic time division duplex (D-TDD) system.

2A to 2B are diagrams illustrating an example of a Co-Channel Interference (CCI) model generated from neighboring cells 203 and 214 that use the same frequency resource when the reference cells 201 and 202 are uplink.

3 is a flowchart illustrating a process of a method of allocating resources in a multi-hop wireless network according to the present invention.

4 is a diagram illustrating an example of reporting, collecting, and distributing channel status according to the present invention.

5 is a diagram illustrating a frame structure for multi-hop resource allocation according to the present invention.

The present invention relates to a method for allocating resources in a wireless communication system. More particularly, the present invention relates to a dynamic resource allocation area in a dynamic time division duplex (D-TDD) system supporting multi-hop. A method for improving the performance of an overall multi-hop wireless network by maximizing uplink performance within the network.

The D-TDD system is a system for supporting asymmetric data services in which the ratio of downlink and uplink is different from each other and the ratio thereof varies with time, like a broadband multimedia mobile communication service. The D-TDD system can flexibly support asymmetric data that changes at any time by setting a separate dynamic resource allocation region in addition to the fixed uplink and downlink links. 1 is a general frame structure of a D-TDD system. The D-TDD frame is divided into a downlink fixed region 101 and an uplink fixed region 103 for supporting a fixed data service, and dynamically allocates resources to downlink or uplink for asymmetric data service in the center portion. Dynamic resource allocation area 102.

A typical TDD system using a fixed uplink / downlink ratio coincides with the starting point of uplink and downlink in order to minimize mutual interference caused by TDD in the surrounding service area. On the other hand, D-TDD system can match the start and end of frame, but in dynamic resource allocation area for asymmetric service, the link direction of neighboring service area and link cannot be matched due to asymmetry of uplink and downlink. Occurs. Especially, in the surrounding service area using the same radio resource, system performance deterioration due to co-channel interference (CCI) is severe, and low frequency reuse factor is used to increase frequency usage efficiency. The more the system is, the greater the impact.

In general, four types of CCI that can occur in the dynamic resource allocation area of the D-TDD system. When the CCI-generating cell has the same link direction based on the link direction of the reference cell, that is, when the reference cell is uplink and neighbor cells are uplink or downlink, and the reference cell is downlink When the neighboring cell is uplink or downlink.

When the reference cell is downlink, that is, when the base station (BS, Base Station) or access point (AP, Access Point) is serviced as a mobile station (MS, Mobile Station), the transmission signal strength of the base station or access point is a mobile terminal Since the antenna is relatively larger than the transmission signal and the location of the base station or the access point is higher than the mobile station, and generally uses an antenna that performs better than the mobile station, interference from neighboring cells is less affected. On the other hand, when the reference cell is uplink, the transmission signal strength, position, and antenna performance of the mobile station are poor compared to the base station or the access point, and thus are easily affected by neighboring cells. 2A to 2B illustrate an example of a CCI model generated from neighboring cells 203 and 214 using the same frequency resource when the reference cells 201 and 212 are uplink. First, in FIG. 2A, the reference cell 201 is uplink and the neighbor cells 203 are the same uplink. The base station BS2 206 in the neighbor cell 203 receives the signal directly from the mobile station MS2 207 while the base station BS1 204 in the reference cell 201 receives a signal from the mobile station MS1 205 (IMS Or a signal via the relay station RS1 209 from the mobile terminal MS3 208 (IRS 210). At this time, the CCI component affecting the reference cell 201 includes uplink signals (IRS 210) and relay station RS1 (209) transmitted from the mobile stations MS2 207 and MS3 208 in the neighbor cell 203. The strength of the uplink signal (IMS 211) interference transmitted to the base station BS2 206 is defined as a path loss between the mobile station and the relay station transmission signal.

2B illustrates a case in which the reference cell 212 is uplink and the neighbor cell 214 is downlink. While the mobile station MS4 216 in the reference cell 212 transmits a signal to the base station BS3 215, the base station BS4 217 in the neighbor cell 214 transmits a signal directly to the mobile station MS5 218 and moves. The terminal MS6 220 transmits a signal via the relay station RS2 219. At this time, the CCI component affecting the reference cell 215 is a signal transmitted by the base station BS4 217 in the neighbor cell 214 (IBS 222) and a signal transmitted by the relay station RS2 219 (IBS 221). And the strength of the interference is defined as the path loss of each signal as above.

Multi-hop technology, which is being actively developed due to low transmission power consumption, increased system capacity, and extended service area, can be utilized as a technology supporting asymmetric data service. Multi-hop relays can be used to distribute intensively required data services to other service areas. In order to use the multi-hop technology, a mobile terminal performing a multi-hop function or a separate multi-hop relay station is required, and radio resource allocation for the multi-hop relay is additionally required. The allocation of radio resources can be separated using different times, frequencies, or codes to minimize interference between multi-hop links and existing links.

The prior art does not consider radio resource allocation for multi-hop in a D-TDD system, and only describes radio resource allocation for multi-hop in a general TDD system. The main factor that determines the performance of the D-TDD system is the degree of performance degradation of uplink due to CCI in the dynamic resource allocation region. Therefore, when allocating radio resources for multiple hops in the D-TDD system, the CCI occurring in the dynamic resource allocation region must be considered.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and combines a D-TDD system and a multi-hop technology to effectively support asymmetric data services that change in time, and determine the performance of the D-TDD system. The present invention provides a method for improving the performance of an overall multi-hop wireless network by allocating multi-hop resources to minimize performance degradation of uplink due to CCI in a dynamic resource allocation area.

In order to achieve the above technical problem, a method for allocating resources in a multi-hop wireless network according to the present invention is a method for allocating radio resources by an apparatus for allocating radio resources in a multi-hop wireless network, wherein the apparatus allocates resources from upper and lower nodes. Receiving an allocation request; Allocating radio resources after constructing a frame according to the request; And reallocating the radio resources so as to minimize Co-Channel Interference (CCI) by monitoring communication channel information between the device and upper and lower nodes.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 3 is a flowchart illustrating a process of a method of allocating resources in a multi-hop wireless network according to the present invention. 4 is a diagram illustrating an example of channel status report, collection, and distribution according to the present invention, and FIG. 5 illustrates a frame structure for multi-hop resource allocation according to the present invention.

A resource allocation request step (step 301), a frame configuration step (302), a step of allocating multi-hop resources in the frame (step 303), a resource allocation step (304) for an uplink and a downlink, In this state, a step of monitoring a channel state (step 305) and reallocating resources according to channel information collected at each node (step 306). The channel information collected at each node is distributed to the base station or access point by combining the channel status reported by each base station or access point in each node, that is, the network controller 401 controlling a plurality of base stations or access points. The information can be selectively used according to the network design and environment.

Each step will be described in detail below.

First, the apparatus for allocating radio resources (which may be equipment such as a base station or an access point) receives a resource allocation request from a network controller or a lower node (for example, a mobile terminal) (step 301). In response to the request, the base station or access point configures a frame including a dynamic resource allocation area and allocates radio resources according to the request. In this case, as shown in FIG. 5, the frame is divided into a downlink region 502, a dynamic resource link region 503, and an uplink region 503, and the dynamic resource link region 503 is configured for downlink. After subdividing into dynamic region 504, dynamic region 505 for multiple hops, and dynamic region 506 for uplink, radio resources are allocated according to the communication channel information provided by network controller 401 ( 302 to 304).

The radio resources are reassigned to receive the result of monitoring the communication channel information to minimize Co-Channel Interference (CCI) (steps 305 to 306). To this end, the base station or access point is based on the channel information distributed from the network controller 401 including the base station or access point to minimize the CCI and to maximize the performance of the multi-hop wireless network multi-hop resources and up and down Allocate link resources step by step. At this time, whether to use the channel information distributed from the network controller can be selectively used according to the network design and environment. That is, whether the channel status report 405 from the RS 403 or the MS 404 to the network controller and the channel information collection 406 and distribution 407 from the network controller may or may not be necessary depending on the purpose of the network. Can be.

4, an embodiment in which the network controller collects channel information and then distributes channel information to each base station or access point will be described. The relay station 403 or the mobile terminal 404 reports the channel state estimated in the data transmission / reception process to the base station or the access point 402 through the control channel (405). The reporting of the channel state through the control channel is already performed for AMC (Adaptive Modulation Coding), etc., and no additional process is required. The base station or access point 402 transmits 406 each channel state collected from a relay station or mobile station included in a service range to a network controller controlling a plurality of base stations or access points. The network controller 401 aggregates the channel state collected from the base station or the access point and distributes the channel information according to the resource (time slot) to the base station or the access point (407). The base station or access point 402 relays or moves the radio resources using different time, frequency, or code to minimize inter-cell interference and maximize the performance of a multi-hop wireless network based on channel information distributed from the network controller. Assign to the terminal.

5 illustrates a frame structure for multi-hop resource allocation in the above-described D-TDD system. The frame structure is summarized as follows. The D-TDD frame for the multi-hop is divided into a downlink fixed region 501 and an uplink fixed region 503 for supporting a fixed data service as in the conventional D-TDD frame, and is a dynamic resource for asymmetric data service. It is composed of a dynamic resource allocation area 502 that can be allocated. The D-TDD frame for the multi-hop of the present invention includes a downlink dynamic region 504 and an uplink dynamic region 506 for asymmetric data service in a dynamic resource allocation region, and a multi-hop dynamic region 505 for multi-hop. Are divided again. Asymmetric data service for dynamic resource allocation area and resource allocation for multi-hop are allocated to minimize CCI and maximize performance of multi-hop wireless network using channel information.

Implement a system that combines a D-TDD system to support asymmetric data services that vary in downlink and uplink and vary with time, and a multi-hop technology capable of low transmission power consumption, system capacity, and service area expansion. In order to minimize the performance degradation caused by CCI in dynamic resource allocation. In particular, when a link of a reference cell is uplink and a cell providing interference is downlink, interference by CCI should be minimized. This is because the interference signal by the base station is more dominant than the interference by the mobile terminal or the relay station among the interference components affecting the system performance. The present invention minimizes downlink allocation of neighboring cells in the dynamic resource allocation region by allocating resources for multiple hops in the dynamic resource allocation region in order to minimize interference by the base stations of neighboring cells during uplink. Interference was minimized. In particular, we proposed a method of minimizing interference and maximizing the performance of a multi-hop wireless network by allocating resources based on channel information of neighboring cells that provide interference and the reference cell for resource allocation for multi-hop. It can be selectively applied according to design and environment.

The method of allocating resources in a multi-hop wireless network according to the present invention can be implemented as computer readable codes on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disks, optical data storage devices, and also implemented in the form of carrier waves (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. And functional programs, codes and code segments for implementing the present invention can be easily inferred by programmers in the art to which the present invention belongs.

As described above, optimal embodiments have been disclosed in the drawings and the specification. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not intended to limit the scope of the present invention as defined in the claims or the claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the method for allocating resources in a multi-hop wireless network according to the present invention combines a multi-hop technology with a D-TDD system for effectively supporting time-varying asymmetric data services, and provides a multi-hop wireless network. Resources can be allocated to reduce the performance degradation of the D-TDD system caused by the mismatch of uplink and downlink intervals between constituting cells.

In particular, multi-hop radio is ultimately allocated by allocating multi-hop resources in the dynamic resource allocation region to minimize the interference between the same channels in the dynamic resource allocation region that determines the performance of the D-TDD system, that is, the performance degradation of the uplink due to the CCI. You can improve the overall performance of your network.

Claims (3)

A method for allocating radio resources by a device for allocating radio resources in a multi-hop wireless network, (a) the device receiving a resource allocation request from a parent node; (b) According to the request, it is divided into a downlink region, a dynamic resource link region, and an uplink region, wherein the dynamic resource link region is a dynamic region for downlink, a dynamic region for multiple hops, and a dynamic region for uplink. Constructing a frame comprising a; (c) allocating radio resources to the respective areas based on communication channel information provided by a network controller; And (d) reallocating the radio resource to minimize co-channel interference (CCI) by monitoring communication channel information between upper and lower nodes connected to the device; How to allocate resources in a wireless network. The method of claim 1, And allocating said radio resources using different times, frequencies, or codes to exclude inter-link interference. The method of claim 1, wherein the communication channel information is A method for allocating resources in a multi-hop wireless network, comprising channel state information according to the radio resource allocation, through a control channel between the device and upper and lower nodes.

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