KR20050091582A - Method for transmission of downlink channel quality indication in broadband wireless access system - Google Patents

Abstract

The present invention discloses an uplink channel allocation and signaling method for downlink channel quality indication (hereinafter referred to as "CQI") in a broadband wireless access system. In the present invention, the base station allocates a portion of the uplink for CQI information, and the subscriber station receives the parameters using the CQI channel region from the base station during the initialization process, and the base station also assigns specific subscribers whenever necessary. By changing the CQI related parameters of the terminal or the subscriber station, the subscriber station does not need to read the UCC-Region-IE every time to the UL-MAP, and the base station can transmit the UCC-Region-IE according to the situation Make sure that resources are managed efficiently.

Description

Method for transmission of downlink channel quality indication in broadband wireless access system

The present invention relates to uplink channel allocation and signaling method for downlink channel quality indication in a broadband wireless access system. In particular, the present invention relates to adaptive modulation and coding (AMS) in a broadband wireless access system. The present invention relates to a method for enabling subscriber stations receiving high-speed downlink data from a base station to transmit downlink channel quality indication (CQI) information to the base station.

In general, according to the IEEE P802.16REVd / D3-2004 standard, a subscriber station may have a ranging request message (hereinafter referred to as 'RNG-REQ') or a downlink burst profile change request (hereinafter referred to as 'DBPC'). CQI information of the downlink is reported by sending a message to the base station. In addition, upon performing the report, the burst profile, that is, the AMC level, to be received is requested.

Then, the base station receiving the request from the subscriber station is a ranging response (Ranging Response, hereinafter 'RNG-RSP') message or Downlink Burst Profile Change Response (hereinafter 'DBPC-RSP') The message is transmitted to the subscriber station.

Next, a process of changing the burst profile as described above with reference to FIG. 1 will be described in detail below.

1 is a diagram illustrating a burst profile change procedure according to an orthogonal frequency division multiple access (OFDMA) system of the IEEE P802.16REVd / D3-2004 standard according to a typical embodiment, wherein reference numeral 101 denotes a base station. Reference numeral 102 denotes a subscriber station.

Referring to FIG. 1, in step 103, when the base station 101 transmits downlink data to the subscriber station 102, a downlink interval usage code indicating a burst profile or an AMC level is referred to as a “DIUC”. Value is set to n and transmitted (DL Data at DIUC n).

The subscriber station 102 then monitors a carrier to noise and interference ratio (CINR) indicating the signal quality of the downlink in step 104. As a result of the monitoring, if the average value is out of the allowable operating range, a series of procedures for changing the burst profile or the AMC level is performed.

First, in step 105, the subscriber station 102 transmits a CDMA code for transmitting a bandwidth request (hereinafter referred to as 'BW-REQ') header to the base station 101 in a competitive manner (CDMA code for BW-REQ).

Then, when the base station 101 successfully receives the CDMA code from the subscriber station 102, the CDMA of the uplink map message (hereinafter referred to as 'UL-MAP') in step 106 is received. A resource for BW-REQ header transmission is allocated to the subscriber station 102 through an allocation information element (hereinafter referred to as 'IE') (CDMA Allocation IE in UL-MAP).

Subsequently, the subscriber station 102 waits for the CDMA allocation IE allocation from the base station 101 for a prescribed time from the time when the CDMA code is transmitted. In this case, if the CDMA allocation IE is not received within the prescribed time, the process starts again from step 105 after performing the backoff defined by the standard.

Meanwhile, in step 107, the subscriber station 102 having successfully received the CDMA allocation IE transmits a BW-REQ header to the base station 101 so as to request allocation of a resource for transmitting an RNG-REQ or DBPC-REQ message. (BW-REQ).

Next, when the base station 101 receives the BW-REQ header from the subscriber station 102, the base station 101 allocates the requested resource through the UL-MAP message in step 108 (Resource Grant in UL-MAP). Then, the subscriber station 102 transmits the burst profile or AMC level information to be changed in the RNG-REQ or DBPC-REQ message using the allocated resource to the base station 101 in step 109 (RNG-REQ). or DBPC-REQ to change into DIUC k).

Subsequently, in step 110, the base station 101 transmits an RNG-RSP or DBPC-RSP message to the subscriber station 102 to accept the request of the subscriber station 102 (RNG-RSP or DBPC-RSP). In step 111, the downlink data is transmitted using the changed burst profile or AMC level (DL Data at DIUC k).

The technique according to a typical embodiment as described above is summarized as follows. That is, when the subscriber station transmits a message including downlink CQI information to the base station through the resource request process, the base station determines the AMC level through the reception of the message from the subscriber station.

However, in this case, the following problems occur.

That is, the subscriber station conforming to the OFDMA standard performs all of the CDMA code transmission, the BW-REQ header transmission, and the RNG-REQ or DBPC-REQ message transmission as shown in FIG. 1. Therefore, in the case of transmitting the three messages as described above, there is a problem in that the resources required for transmission increase, and a transmission delay occurs as the resources increase.

In addition, as described in the accompanying drawings as described above, as shown in FIG. 1, a random access delay is encountered, which causes performance degradation in the AMC transmission scheme in which more recent channel quality information is to be transmitted to the base station. There was a problem.

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide more efficient use of radio resources by a base station and a subscriber station in a broadband wireless access system employing an AMC transmission scheme, The present invention provides a method for allocating an uplink channel and indicating a signaling method for indicating a channel quality of a downlink in a broadband wireless access system for enabling faster downlink CQI transmission.

Method for transmitting downlink channel quality indication information in a broadband wireless access system employing the AMC transmission method according to the present invention for achieving the above object,

Determining whether the base station needs to change the CQI channel region allocated in the previous frame in the current frame;

If the CQI channel region needs to be changed as a result of the determination, the region to be changed in the UCC_Region_IE is coded and included in the UL-MAP, and then the CQI channel allocation information to be changed according to the change of the CQI channel region is configured for each subscriber station, Transmitting to the terminal,

Determining that the CQI channel allocation needs to be changed by the subscriber station when the CQI channel region does not need to be changed as a result of the determination;

If a change is necessary, the method includes configuring the CQI channel allocation information for each subscriber station and transmitting the same to the subscriber station.

In addition, a method for transmitting downlink channel quality indication information in a broadband wireless access system employing the AMC transmission scheme according to the present invention for achieving the above object,

Confirming, by the subscriber station, the size of the UCCI bit on the SICH broadcasted by the base station;

Updating the CQI channel allocation information after receiving the UCC_Region_IE in the UL-MAP message broadcasted by the base station when the UCCI bit is set to 1 as a result of the checking;

Confirming whether there is a CQI channel allocated to the current uplink by the subscriber station after the update, and transmitting the CQI information on the corresponding CQI channel if it exists;

If the UCCI bit is set to 0, the subscriber station receives the CQI channel allocation message from the base station and updates the CQI channel allocation information based on the CQI channel allocation message information.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

First, prior to the detailed description of the drawings, in the method proposed in the present invention, a base station allocates a portion of an uplink for every frame for transmitting CQI information of subscriber stations, and the subscriber station performs a network entry process at the subscriber station and the base station. The base station to perform the CQI channel assignment while transmitting the RNG-RSP message to the subscriber station, and the base station can change the CQI channel assignment to one or more subscriber stations when the base station needs to change the CQI channel assignment. By doing so, the base station can dynamically allocate the CQI channel region and signal the subscriber stations more efficiently in resource usage.

2 is a diagram illustrating a CQI channel region allocation and signaling process in a TDD OFDMA frame structure according to the present invention, and illustrates a process of allocating a CQI channel region and signaling to a subscriber station in the present invention using the TDD OFDMA frame structure. It is a figure for following.

Referring to FIG. 2, a TDD OFDMA frame first starts with a DL preamble 210 indicating a start of a frame, followed by a system information channel (SICH) for broadcasting system information. (Abbreviated as) 220 is present. Following the SICH 220, there is a DL-MAP indicating resource allocation information of a downlink subframe and a UL-MAP indicating resource allocation information of an uplink subframe.

In the present invention, one bit information of the SICH and a part of an uplink subframe are set to the CQI channel region through the UL-MAP. That is, one bit of the SICH 220 is set to an Uplink Control Channel Information Element Indicator (hereinafter, referred to as 'UCCI'). If the value is 1, UCC_Region_IE is set to UL-MAP of the current frame. Is present and if the value is 0, it indicates that UCC_Region_IE does not exist in the UL-MAP of the current frame (230a).

Here, the UCC_Region_IE, which may exist in the UL-MAP, indicates a location where channel regions related to system control exist in an uplink subframe of the current frame (240). As an embodiment of the present invention, it is assumed that channel areas related to the system control are divided into a ranging channel area, an ACK channel area, and a CQI channel area, and that UCC_Region_IE is coded as shown in Table 1 to indicate the location of the areas. do. However, the present invention is not limited thereto.

Table 1 shows the UCC_Region_IE format, and it can be seen that the UCC_Region_IE present in the UL-MAP indicates the size of the ranging channel, the size of the ACK channel, and the size of the CQI channel. This is possible by dividing the first three symbols constituting the uplink subframe in FIG. 2 into three regions on the frequency axis and indicating the number of subchannels occupying each region.

Meanwhile, in the accompanying FIG. 2, in the case of the K + 1 th TDD OFDMA frame, the UCCI bit of the SICH is set to 0 (230b). Accordingly, the UCC_Region_IE does not exist in the UL-MAP, which indicates that the CQI channel region allocated in the K-th TDD OFDMA frame is used as it is in the K + 1 th TDD OFDMA frame (250b).

The method of allocating and signaling the CQI channel region as described above may prevent resource waste (each message transmission routine as shown in FIG. 1) due to an increase in the UL-MAP size that occurs when displaying the CQI channel region every frame. do.

In addition, in the present invention, in order for the subscriber stations newly accessing the base station to recognize the CQI channel region within a predetermined time, the CQI channel region periodically transmits even when the CQI channel region is not changed.

Meanwhile, the subscriber stations that recognize the CQI channel region through signaling of the base station as shown in FIG. 2 share the CQI channels allocated to the CQI channel region on a frame basis. To this end, the base station transmits a CQI channel to a specific subscriber station. It is necessary to inform the allocation information. Signaling of the CQI channel allocation information will be described with reference to FIG. 3.

3 is a diagram illustrating a CQI channel allocation of a base station and a transmission of CQI information of a subscriber station in a network entry process according to the present invention, and shows a subscriber station through CQI channel allocation of the base station in a network entry process between a base station and a subscriber station. Shows a process of periodically transmitting the CQI information.

Referring to FIG. 3, when the base station 310 receives an RNG-REQ message for initial ranging from the subscriber station 320 (330), the base station 310 transmits an RNG-RSP message to the uplink parameter correction value. A basic connection identifier (hereinafter referred to as a basic CID) and a primary connection identifier (primary CID) are allocated to the subscriber station (340).

At this time, the base station 310 allocates a CQI channel to the subscriber station 320. For this purpose, the RNG-RSP message is a type length value (Type, length, and value, hereinafter referred to as 'TLV'. Here, Table 2 shows TLV encoding related to CQI channel allocation in an RNG-RSP message.

Referring to Table 2, the CQI_CH_Allocation TLV field is a compound TLV and includes three dependent TLV fields, that is, a frame offset, a CQI CH index, and a Period TLV field. .

First, the Frame offset field has a value of 1 byte and indicates a time interval from a frame where a subscriber station receives an RNG-RSP message including the TLV to a frame at which CQI information is transmitted, and a unit thereof. Is represented by a frame.

Next, the CQI CH index field, which is a dependent TLV field, also has a value of 1 byte, and indicates a CQI channel allocated in the CQI channel region defined as shown in FIG. 2, wherein the CQI channel is The RNG-RSP message is assigned to the subscriber station to which it is sent.

Lastly, the Period field, which is a dependent TLV field, also has a value of 1 byte, and indicates a period of using a CQI channel corresponding to a CQI CH index in the CQI channel region. The unit is represented by a frame.

Meanwhile, the subscriber station 320 allocated to the CQI channel through step 340 of FIG. 3 performs a network entry process with the base station 310, and on the other hand, determines the quality of the downlink signal transmitted from the base station 310. The CINR value that can be displayed is monitored and the average value is transmitted to the base station 310 periodically as CQI information (360a, 360b, 360c).

The base station 310 that receives the CQI information determines the optimal burst profile or AMC level that the subscriber station 320 can receive based on the information, and again determines the determined AMC level. After transmitting the RNG-RSP or DBPC-RSP message, the downlink data can be transmitted at the changed AMC level.

Here, in general, the base station allocates a CQI channel to the subscriber station when the specific subscriber station performs a network entry process as shown in FIG. However, the present invention is not specifically dealt with, that is, it may be necessary to change the CQI channel allocation parameter of a specific subscriber station due to terminal transition to a sleep mode or handover of the terminal. Accordingly, the base station can dynamically change the CQI channel parameter by transmitting the CQICH-ALC (CQICH-ALC) message shown in Table 3 below to the subscriber station or subscriber stations that need to change the CQI channel parameter. Table 3 shows the CQICH-ALC message structure.

Here, the CQICH-ALC message is a MAC management message transmitted through broadcast-CID, and starts with an 8-bit management message type field according to the IEEE P802.16REVd / D3-2004 standard. The second field is an 8-bit number of subscriber station's (SSs) field, which indicates the number of subscriber stations included in the CQICH-ALC message. The third field is repeated by the value of the Number of SSs field, and has a total length of 24 bits per SS. The 24 bits are composed of a Reduced CID field occupying the upper 10 bits, a Frame offset field occupying 3 bits space, a CQI CH index field having a 7-bit length, and a 4-bit Period field.

The reduced CID field is a field having a lower 10-bit value of Basic CID, and is a field for identifying a subscriber station. The other three fields are the same fields as the CQI channel allocation-related TLV fields of Table 2, which differ only in the length of each field.

Hereinafter, preferred embodiments of the operation between the base station and the subscriber station according to the present invention will be described with reference to the accompanying drawings, FIGS. 4 and 5.

4 is a diagram illustrating a signaling operation sequence of a CQI channel region and CQI channel allocation information by a base station according to the present invention.

Referring to FIG. 4, the base station determines whether the CQI channel region needs to be changed in the previous frame (410), and if it is necessary to change the CQI channel region, sets the UCCI bit of the SICH to 1 (420). After coding the changed region in the UCC_Region_IE to include in the UL-MAP (430), and after the inclusion of the UCC_Region_IE to configure the CQI channel allocation information for each subscriber station at least one or more through the RNG-RSP message or CQICH-ALC message A step 440 of transmitting to the subscriber station; and a determination of the necessity of changing the CQI channel allocation of the subscriber station if the change of the CQI channel region is not necessary in the current frame (450); and the confirmation result If a change is necessary, the CQI channel allocation information to be changed is configured for each subscriber station, and at least one or more provisional information is transmitted through an RNG-RSP message or a CQICH-ALC message. Transmitting (440) to those terminals, and comprises a step of, if you are not required to complete the operation.

Looking at the signaling operation of the CQI channel region and the CQI channel allocation information by the base station according to the present invention having such a configuration as follows.

First, the base station examines whether it is necessary to change the CQI channel region allocated in the previous frame in the current frame (410). In this case, when a change in the CQI channel region is required, the UCCI bit of the SICH is set to 1 (420), and the region changed in UCC_Region_IE according to the format of FIG. 1 is coded and included in the UL-MAP (430).

Subsequently, the CQI channel allocation information to be changed together according to the change of the CQI channel region is configured for each terminal and transmitted to the subscriber station or the subscriber stations through the RNG-RSP message or the CQICH-ALC message (440).

If it is determined in step 410 to use the same CQI channel region as the previous frame, the necessity of changing the CQI channel allocation of the subscriber station without performing steps 420 and 430 is examined (450). Performs step 440, and completes the operation if not necessary.

On the other hand, as an example of the CQI channel allocation change occurs in step 450, the specific subscriber station assigned the CQI channel is a sleep mode (Sleep mode: uplink / downlink traffic does not occur in the prior art is transmitted for a predetermined time / Non-receiving mode), which may occur when a CQI channel is allocated and reassigned to a subscriber station newly connecting or returning from the sleep mode to the normal mode. However, the present invention is not limited thereto, and it should be noted that such an example may occur in many cases not mentioned in the present invention as an embodiment.

5 is a diagram illustrating an operation sequence of CQI information transmission by a subscriber station according to the present invention.

Referring to FIG. 5, in step 510, the subscriber station determines whether the UCCI bit is set to 1 on the SICH broadcasted by the base station, and if the UCCI bit is set to 1, the UL-MAP message broadcasted by the base station. Receiving UCC_Region_IE at step 520 to update the information of the region allocated to the CQI channel (530), and updating the CQI channel allocation information at step 540 after updating the CQI channel region information (540); As a result, when the UCCI bit is set to 0, the subscriber station checks whether the CQI channel allocation message is received from the base station (550), and when receiving the check result message, updates the CQI channel allocation information (540) and does not receive it. If not, proceed to the next step, after updating the CQI channel allocation information of the step 540 or if the message is not received in step 550 the current phase Checking whether there is a CQI channel allocated to the downlink (560); and if the allocated CQI channel exists, transmitting the CQI information on the corresponding CQI channel (570), and assigning the allocated CQI channel. If it does not exist, it consists of completing the operation and returning it.

Looking at the operation of the CQI information transmission by the subscriber station according to the present invention having such a configuration as follows.

First, the subscriber station checks whether the UCCI bit is set to 1 on the SICH broadcasted by the base station (510), and receives the UCC_Region_IE from the UL-MAP message broadcasted by the base station when the UCCI bit is set to 1 ( In operation 530, a region allocated to the CQI channel is identified in the current frame. The subscriber station performing step 530 updates the CQI channel allocation information based on the CQI channel allocation message information received from the base station (540).

On the other hand, when the UCCI bit is set to 0 in step 510 (when reusing previously allocated CQI channel region information), the subscriber station according to whether to receive a CQI channel assignment message from the base station (550), In case of the reception, the operation 540 is performed, and in the case of not receiving the operation, the operation 560 is performed.

In step 560, the subscriber station determines whether there is a CQI channel allocated to the current uplink based on the updated or previous CQI channel allocation information (560), and then the CQI channel allocated to the subscriber station exists. In this case, the CQI information is transmitted on the corresponding CQI channel (570), or the process starts again from step 510 in the next frame.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims to be described.

According to the assignment of an uplink channel for downlink channel quality indication and a signaling method thereof in the broadband wireless access system of the present invention, more efficient use of radio resources by a base station and a subscriber station in a broadband wireless access system employing the AMC transmission scheme and Faster downlink CQI transmission by the subscriber station has the advantage that it is possible.

In addition, the base station allocates a portion of the uplink for the CQI information, the subscriber station is assigned to the parameters using the CQI channel region from the base station during the initialization process, and also the base station to the specific subscriber station or subscriber whenever necessary By allowing the CQI related parameters of the terminals to be changed, the subscriber station does not need to read the UCC-Region-IE every time to the UL-MAP, and the base station can transmit the UCC-Region-IE according to the situation so that system resources can be efficiently saved. Has the advantage of being managed.

1 is a diagram illustrating a burst profile change procedure according to the OFDMA system of the IEEE P802.16REVd / D3-2004 standard according to a typical embodiment;

2 is a diagram illustrating an allocation and signaling process of a CQI channel region in a TDD OFDMA frame structure according to the present invention;

3 is a diagram illustrating a CQI channel allocation of a base station and CQI information transmission of a subscriber station in a network entry process according to the present invention;

4 is a diagram illustrating a signaling operation sequence of a CQI channel region and CQI channel allocation information by a base station according to the present invention;

5 is a diagram illustrating an operation sequence of CQI information transmission by a subscriber station according to the present invention.

Claims (2)

A method for transmitting downlink channel quality indication information in a broadband wireless access system employing the AMC transmission method, Determining whether the base station needs to change the CQI channel region allocated in the previous frame in the current frame; If the CQI channel region needs to be changed as a result of the determination, the region to be changed in the UCC_Region_IE is coded and included in the UL-MAP, and then the CQI channel allocation information to be changed according to the change of the CQI channel region is configured for each subscriber station, Transmitting to the terminal, Determining that the CQI channel allocation needs to be changed by the subscriber station when the CQI channel region does not need to be changed as a result of the determination; The method comprising the step of configuring the CQI channel allocation information for each subscriber station and transmitting to the subscriber station if the change is necessary. A method for transmitting downlink channel quality indication information in a broadband wireless access system employing the AMC transmission method, Confirming, by the subscriber station, the size of the UCCI bit on the SICH broadcasted by the base station; Updating the CQI channel allocation information after receiving the UCC_Region_IE in the UL-MAP message broadcasted by the base station when the UCCI bit is set to 1 as a result of the checking; Confirming whether there is a CQI channel allocated to the current uplink by the subscriber station after the update, and transmitting the CQI information on the corresponding CQI channel if it exists; And if the UCCI bit is set to 0, receiving the CQI channel allocation message from the base station and updating the CQI channel allocation information based on the CQI channel allocation message information. .