This application claims the benefit under 35 U.S.C. § 119(a) of an application filed in the Korean Intellectual Property Office on Oct. 28, 2005 and assigned Serial No. 2005-102361, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates generally to a wireless mobile communication system, and in particular, to a method for transmitting and receiving data in a wireless mobile communication system using a multi-hop scheme.
2. Description of the Related Art
Presently, wireless mobile communication systems have developed from the 3rd Generation mobile communication system into the 4th Generation mobile communication system. Research on the 4th Generation mobile communication system is being conducted not only to provide a higher rate, but also to extend the wireless transmission range, i.e. the service area. A multi-hop scheme has been proposed for the extension of the service area. In the multi-hop scheme, a relay node designed at low cost for communication with the nodes located outside the cell coverage uses a method of relaying signals to the nodes located outside the cell coverage.
A Wideband Code Division Multiple Access (W-CDMA) system employs multi-hop technology in which a user node (UE) serves as a relay based on an Opportunity Driven Multiple Access/Time Division Duplexing (ODMA/TDD) scheme, thereby extending coverage of the cellular network. In ODMA/TDD system, when a UE located outside the cellular coverage desires to communicate with a Node B, a UE located in the intermediate route serves as a relay node.
Referring to
Referring to
However, the ODCH and ORACH slots should occupy some of the general slots for relay in a fixed manner. This is because it is not possible to adaptively allocate the ODCH or the ORACH when the traffic load changes abruptly due to movement of a mobile station, or when the traffic change is considerable even in a short interval, like Internet service.
That is, when a more than required number of fixed ODCH and ORACH slots are allocated in the frame, resource waste occurs, and when a less than required number of the fixed ODCH and ORACH slots are allocated in the frame, time delay occurs during data transmission, making it impossible to satisfy Quality of Service (QoS) of the mobile station.
It is, therefore, an object of the present invention to provide a new frame structure in a multi-hop wireless mobile communication system.
It is another object of the present invention to provide a new operation scenario for transmitting and receiving data in a multi-hop wireless mobile communication system.
According to one aspect of the present invention, there is provided a method for transmitting and receiving data in a multi-hop wireless mobile communication system having a first mobile station (MS), a second MS, a base transceiver station (BTS), and a relay BTS. The method includes allowing the first MS to directly communicate with the BTS, and allowing the second MS to communicate with the BTS by relay of the relay BTS; performing communication between the BTS and the first MS and communication between the relay BTS and the second MS using a first frame; and performing communication between the BTS and the relay BTS using a second frame.
According to another aspect of the present invention, there is provided a method for exchanging data with a mobile station (MS) by a relay base transceiver station (BTS) in a multi-hop wireless mobile communication system having a BTS and the relay BTS, the relay BTS relaying an MS signal transmitted to the BTS. The method includes making access to the BTS using a first frame; receiving a resource allocated from the BTS after authentication thereof; if the MS attempts an access to the relay BTS, notifying the BTS of the attempt using a second frame; upon receipt of a notification indicating completed authentication on the MS from the BTS, notifying the MS of the completed authentication using the first frame; and allocating some or all of resources allocated from the BTS to the MS, and exchanging data with the MS using the allocated resource.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:
Preferred embodiments of the present invention will now be described in detail with reference to the annexed drawings. In the following description, a detailed description of known functions and configurations incorporated herein has been omitted for clarity and conciseness.
The present invention provides a new frame structure for efficiently using a multi-hop scheme in a multi-hop wireless mobile communication system, and presents an operation scenario for exchanging data between a base transceiver station (BTS), a mobile station (MS), and a relay BTS, or multi-hop BTS (“MH-BTS”), according to the new frame structure.
The present invention is applicable to a wireless mobile communication system using a multi-hop scheme (“multi-hop wireless mobile communication system”), and is preferably applicable to a communication system using an Orthogonal Frequency Division Multiple Access (OFDMA) scheme.
Referring to
In the communication system where only the BTS and MS exist, when the MH-BTS is added, the system takes into consideration not only the resources for data exchange between the BTS and the MS, but also the resources for delay, i.e. wireless resources allocated for data exchange between the MH-BTS and the MS, and wireless resources allocated for data exchange between the MH-BTS and the BTS.
The present invention uses a Time Division Duplexing (TDD) technique that time-shares all wireless resources. Accordingly, the present invention newly proposes a Type-A frame for data exchange between the BTS/MH-BTS and the MS that communicates directly with the BTS/MH-BTS, and a Type-B frame for data exchange between the BTS and the MH-BTS. A detailed description of the Type-A and Type-B frame structures will be made with reference to
Referring to
Referring to
Because the Type-A and Type-B frames are time-divided as described with reference to
The BTS selects one of the Type-A frame and the Type-B frame depending on traffic distribution. For example, if there is a large amount of data that the BTS exchanges with the MH-BTS, the BTS increases a frequency of use of the Type-B frame, and if there is a large amount of data that the BTS exchanges with an MS located in its own cell, the BTS increases a frequency of use of the Type-A frame.
Referring to
First, it is assumed that a BTS communicates with an MS located in its own cell using the Type-A frame.
If the BTS maps its own BTS ID to the preamble region 601 and then transmits the signal to an MS, the MS can perform frame synchronization acquisition and channel estimation by receiving the preamble.
The FCH region 603 includes therein size information indicating a percentage of the MAP region 605 in the frame, Modulation and Coding Scheme (MCS) level information, an identifier for frame type identification, and information indicating the time the Type-A frame is to be used next. The information on the time the Type-A frame is to be used can include offset information corresponding to a difference between a frame index where the BTS currently uses the Type-A frame and a frame index where the BTS will next use the Type-A frame. If the current frame index is 3 and the offset value is 2, the BTS previously notifies the MS that it will use the Type-A frame in the next frame, i.e. a frame with frame index=5.
The MAP region 605 includes therein uplink/downlink resource allocation information, and the downlink region 607 and the uplink region 609 each include therein data and control information exchanged with the MS.
The access region 611 is used by an MS or an MH-BTS to randomly access the BTS.
Next, it is assumed that an MH-BTS communicates with an MS located in its own cell using the Type-A frame.
If the MH-BTS maps its own MH-BTS ID to the preamble region 601 and then transmits the signal to an MS, the MS can perform frame synchronization acquisition and channel estimation by receiving the preamble.
The FCH region 603 includes therein size information indicating a percentage of the MAP region 605 in the frame, MCS level information, an identifier for frame type identification, and information indicating the time the Type-A frame is to be used next, i.e. an offset value.
The MAP region 605 includes therein uplink/downlink resource allocation information, and the downlink region 607 and the uplink region 609 each include therein data and control information exchanged with the MS.
The access region 611 is used by an MS to randomly access the MH-BTS.
A description will now be made of a scenario where the BTS and the MH-BTS use the Type-B frame.
When the BTS and the MH-BTS use the Type-B frame, an ID of the BTS is mapped to the preamble region 613, and the MS can acquire synchronization with a tracking mode or an initial mode and perform channel estimation using the preamble.
The FCH region 615 includes therein size information indicating a percentage of the MAP region 617 in the frame, MCS level information, an identifier for frame type identification, and information indicating the time the Type-B frame is to be used next, i.e. an offset value.
The MAP region 617 includes therein uplink/downlink resource allocation information, and the downlink region 619 and the uplink region 621 each include therein data and control information exchanged between the BTS and the MH-BTS.
The dedicated control channel region 623 is used by the MH-BTS to request resource allocation. The dedicated control channel region 623 includes Acknowledge (ACK)/Negative-Acknowledge (NACK) information, and is used by the MH-BTS to transmit fast feedback-required control information to the BTS.
Because the signals exchanged between the BTS and the MH-BTS include data for a plurality of MSs, the BTS and the MH-BTS can perform efficient data exchange by aggregating data of the same type and distinguishing the data with a relay header.
Referring to
The relay header region 701 includes message type information, MH-BTS ID information, and total message length information. The MH-BTS ID information is used by the BTS to determine with which MH-BTS the corresponding data is associated. The message type information is used to determine to which message (for example, access, authentication, etc.) the transmission/reception information corresponds. The total length information is used to indicate an end of the message.
The MAC header region 703 includes destination information and length information of a payload, and allows the BTS and the MH-BTS to decode the MAC header and determine with which MS the corresponding payload is associated.
The resource allocation information included in the MAC region 605 or 617 shown in
Referring to
A description will now be made of a method in which the BTS allocates the Type-A frame and the Type-B frame.
The frame allocation method is provided on the assumption that when the BTS and the MH-BTS perform communication using the Type-B frame, they do not use the Type-A frame for communication with the MS, and when the BTS or the MH-BTS communicates with the MS using the Type-A frame, it does not use the Type-B frame.
Referring to
Table 1 below shows exemplary information inserted in an FCH in each of the frames of
In Table 1, F_type is used for distinguishing between a Type-A frame and a Type-B frame, and an Offset value includes the information indicating in which frame following the current frame a frame of the same type is to be used. For example, information inserted in an FCH of the frame 901 indicates that the current frame is a Type-A frame, and the Type-A frame will be used again in the second frame.
Referring to
Table 2 below shows exemplary information inserted in an FCH of the frame of
When there is relay traffic, i.e. when there is data that the BTS will transmit to the MH-BTS, or when the MH-BTS sends a request for uplink resource allocation to the BTS, the BTS appropriately determines an offset value such that it can rapidly use the Type-B frame. However, if there is no relay traffic, the BTS decreases a frequency of use of the Type-B frame by multiplying an offset value inserted in an FCH of the Type-B frame by a predetermined integer.
Referring to
The MS21100 requests the resources necessary for data exchange using the basic resources allocated from the BTS 1130 (Step 1107). The MH-BTS 1150 recognizes access attempt from an MS11170 connected thereto in one hop (Step 1123). Upon recognizing the access attempt of the MS11170, the MH-BTS 1150 relays access information of the MS11170 at the time the BTS 1130 uses the Type-B frame (Step 1125). In the next Type-B frame, the BTS 1130 completes authentication on the MS11170 to the MH-BTS 1150 (Step 1127). The MH-BTS 1150 provides authentication-completed information to the MS11170 (Step 1131), allocates basic resources to the MS11170 (Step 1133), and receives a required-resource allocation request from the MS11170 (Step 1135).
Upon receipt of the required-resource allocation request from the MS11170, the MH-BTS 1150 sends a required-resource allocation request to the BTS 1130 using the Type-B frame (Step 1137), and is allocated uplink resources from the BTS 1130 (Step 1139). The MH-BTS 1150 allocates some or all of its allocated uplink resources to the MS11170 (Step 1141), and receives data from the MS11170 (Step 1143). The non-described steps include steps in which the BTS 1130 or the MH-BTS 1150 allocates wireless resources to the MSs 1100 and 1170 and receives data therefrom, and steps in which resource allocation request, resource allocation, and data exchange are performed between the BTS 1130 and the MH-BTS 1150. These steps are similar to the steps described above, so a description thereof will be omitted.
As described above, signal exchange between the BTS 1130 and the MS21100 and signal exchange between the MH-BTS 1150 and the MS11170 are performed using the Type-A frame, and signal exchange between the BTS 1130 and the MH-BTS 1150 is performed using the Type-B frame. Exchange of control information and data between the BTS 1130 and the MH-BTS 1150 is achieved based on a message in the Type-B frame. Therefore, the BTS 1130 and the MH-BTS 1150 can distinguish between a source MS and a target MS according to MAC header information of received data. For example, in step 1125 of
Referring to
Table 3 shows information and data included in each region of the frame structure of
As can be understood from the foregoing description, the present invention provides new frames and an operation method thereof so as to allow a BTS and a relay BTS (MH-BTS) serving as a relay to simultaneously operate in a multi-hop wireless mobile communication system, thereby contributing to improvement in wireless resource efficiency. In addition, because a data exchange method between the BTS and the MS is equal to a data exchange method between the BTS and the relay BTS, the new system can reduce its system complexity compared with other systems having a relay function.
While the invention has been shown and described with reference to a certain preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Number | Date | Country | Kind |
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2005-102361 | Oct 2005 | KR | national |