KR20030022490A - Selective Combining Method Of Uplink Frame Data In IMT-2000 Vocoder - Google Patents

Abstract

The present invention provides improved frame data selection for uplink frames received through each base station in a boundary area during soft handoff of a vocoder performing a handoff function in a base station controller of an International Mobile Telecommunication-2000 (IMT-2000) system. The present invention relates to a method of selecting and combining uplink frame data of an IMT-2000 vocoder capable of improving voice quality and data service quality by implementing a combining function. Conventionally, it is included in an actual frame for a frame received through each base station. As handoff function was performed by selecting and combining any one frame by frame irrespective of the data, detailed control for each transport channel was not possible. Therefore, even transport layer or TB block Up to select poor quality data This increases was a problem.

Accordingly, the present invention uses the Quality Estimate (QE) included in the uplink frame received through each base station during soft handoff in the IMT-2000 vocoder and the cyclic redundancy check indicator (CRCI) for each TB block. By selecting and combining only good TB blocks, it is possible to improve the reliability of the transport layer.

In addition, the present invention selects and combines only high quality TB blocks in each uplink frame during soft handoff, and transmits them to a higher layer, thereby maintaining system performance by maintaining excellent voice call quality or reducing the number of retransmissions for data services. It can be improved.

Description

Selective Combining Method Of Uplink Frame Data In IMT-2000 Vocoder

The present invention relates to a vocoder performing a handoff function in a base station controller of an international mobile telecommunication-2000 (IMT-2000) system, and in particular, to an uplink frame received through each base station in a boundary area during soft handoff. The present invention relates to an uplink frame data selection and combination method of an IMT-2000 vocoder capable of improving voice quality and data service quality by implementing a frame data selection and combination function.

Recent advances in the Global System for Mobile communications (GSM) and Code Division Multiple Access (CDMA) technologies in the mobile telecommunications sector provide high-speed data services such as the Internet and video, and aim for global roaming by using global standardization and the same frequency band. As a result, the IMT-2000 system has been standardized and prepared for service as a next generation mobile communication with high speed, high quality, and advanced service compared to currently provided mobile phones.

A schematic network configuration of such an IMT-2000 system includes a base station (BTS) that performs termination function for matching with a subscriber station and a wireless standard, and for the IMT-2000 that is the center of the IMT-2000 network. An ATM (Asynchronous Transfer Mode) switch and a base station controller (BSC; Base Station Controller) connected to the ATM switch to accommodate a plurality of base stations and perform a handoff function, wherein the base station controller is a handoff Since the frame data may be received in a broken state according to a wired / wireless state, the vocoder may perform a frame-selective combining function for handoff.

Here, the handoff refers to a soft handoff that does not interfere with the call when the subscriber station moves between the base station and the base station during the call. FIG. 1 is an example of the soft handoff. FIG. 1 illustrates a case where a subscriber station in a call performs soft handoff for three base stations BTS0, BTS1, and BTS10.

However, in the above-described conventional IMT-2000 base station controller, a vocoder performing a handoff function for a subscriber station is received through three base stations BTS0, BTS1, and BTS10 (three frames are received in the example of FIG. 1). As a handoff function is performed by selecting and combining one frame on a frame basis regardless of data included in an actual frame, in particular, TB (transport block) data passing through a transport channel. Detailed control of each transport channel was not possible, and thus there was a problem that the possibility of selecting poor quality data was increased by going up to the transport layer or TB block.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems described above, and an object thereof is to provide a QE (Quality Estimate) included in an uplink frame received through each base station during soft handoff in an IMT-2000 vocoder and for each TB block. By using the Cyclic Redundancy Check Indicator (CRCI), only high-quality TB blocks are selected and combined and transmitted to the upper layer, which improves the reliability of the transport layer while maintaining excellent voice call quality or the number of retransmissions for data services. To improve system performance.

1 is a diagram illustrating a case where a subscriber station in a call in the IMT-2000 communication network performs soft handoff for three base stations.

FIG. 2 illustrates an uplink frame path for the case where the soft handoff illustrated in FIG. 1 is made. FIG.

3 is a flowchart of uplink frame data selection and combining operation of an IMT-2000 vocoder according to the present invention;

4 is a diagram illustrating a buffer structure for the IMT-2000 vocoder to select and combine the best quality frame data in the present invention.

5 illustrates an uplink frame structure during soft handoff.

Explanation of symbols on the main parts of the drawings

11, 12, 13: base station 21. 22: base station controller

25: ATM Switch 30: IMT-2000 Vocoder

31, 32, 33: frame buffer 35: combination buffer

A feature of the present invention for solving the above object is a process of receiving a plurality of uplink frames through each base station in the border area where the subscriber station is located at the time of soft handoff and storing in each frame buffer; Selecting TB blocks in which the CRCI is normal within the uplink frame having good QE among the uplink frames stored in each frame buffer, and copying them to the combination buffer; The present invention provides a method of selecting and combining uplink frame data of an IMT-2000 vocoder, including combining TB blocks copied to the combining buffer and transmitting the combined TB blocks to an upper layer.

Here, the process of selecting TB blocks in which CRCI is normal and copying them to a combination buffer includes selecting TB blocks in which CRCI is normal after sequentially selecting uplink frames in order of good QE among uplink frames stored in each frame buffer. Copying to a combination buffer; If there is a TB block in which CRCI is abnormally identified in every uplink frame, QE selects the TB block of the best uplink frame and copies it to the combination buffer.

In the method of selecting and combining uplink frame data of the IMT-2000 vocoder described above, the payload checksum of the uplink frame stored in each frame buffer is sequentially examined to determine whether there is an uplink frame having a normal payload. Process of doing; Copying the entire uplink frame to the combination buffer when there is an uplink frame having a normal paylog; The method may further include transmitting an uplink frame stored in the combination buffer to an upper layer.

In addition, the frame buffer is a buffer for temporarily storing the uplink frames received through one uplink frame path and each base station in the border area from one subscriber station, the combination buffer is different It is characterized in that the buffer for copying and combining the selected frame data in the uplink frame temporarily stored in each frame buffer through the uplink frame path.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the vocoder (hereinafter referred to as 'IMT-2000 vocoder') of the IMT-2000 base station controller according to the present invention, frame selection and combination during soft handoff are selected by DCH unit included in uplink frame, not by frame unit. And a combination thereof, which will be described below with reference to the uplink frame path during soft handoff illustrated in FIG. 2.

Here, FIG. 2 is a diagram illustrating an uplink frame path for a case where the subscriber station performs soft handoff for three base stations 11 to 13, as illustrated in FIG. The uplink frame received through the corresponding base stations 11 to 13 from the subscriber station located in the boundary region of 13) is transmitted to the IMT-2000 vocoder 30 via the base station controllers 21 to 22 or the ATM switch 25. Is received.

The IMT-2000 vocoder 30 selects and combines the best quality frame data from three frames received from one subscriber station through different uplink frame paths. Detailed operations of combining will be described in detail with reference to FIG. 3.

First, the IMT-2000 vocoder 30 includes a plurality of frame buffers 31 to 33 and one combination buffer 35 as shown in FIG. 4 to select and combine the best frame data. In this case, the frame buffers 31 to 33 are buffers for temporarily storing the frames received from the respective base stations 11 to 13 through the uplink frame path, and the combining buffer 35 is provided. The frame data, i.e., quality, selected from frames temporarily stored in each frame buffer 31 to 33 through one uplink frame path and each base station 11 to 13 in the boundary area from one subscriber station during soft handoff. A buffer for copying and combining these best frame data.

The IMT-2000 vocoder having such a buffer structure has a corresponding base station 11 to 13 from one subscriber station in a call in the boundary region of a plurality of base stations (three base stations in the example of FIG. 2) 11 to 13. After receiving a plurality of uplink frames through a path via the base station controllers 21 to 22 that are uplink frame paths, the ATM switch 25, and the like, each of the received uplink frames is stored in a corresponding frame buffer 31 to 33. ) Is temporarily stored (step S31). Here, the uplink frames stored in the frame buffers 31 to 33 have a frame structure as shown in FIG. 5.

The IMT-2000 vocoder 30 selects a good frame by performing a payload check on the uplink frames stored in the respective frame buffers 31 to 33. First, the payload checksum field in the uplink frame stored in each frame buffer 31 to 33 is sequentially checked (step S32) to check whether there is an uplink frame having a normal payload (step S32). S33).

At this time, if there is an uplink frame having a normal payload among the uplink frames stored in the frame buffers 31 to 33, the entire uplink frame is copied to the combination buffer 35 (step S34). This is because the uplink frame in which the payload is normal has little chance of breaking the cyclic redundancy check (CRC) for error detection and correction, and the IMT-2000 vocoder 30 copies the uplink copied to the combination buffer 35 in this manner. The link frame is transmitted to the higher layer (step S35).

However, if there is no uplink frame having a normal payload among the uplink frames stored in the respective frame buffers 31 to 33 in step S33, the IMT-2000 vocoder 30 performs QE (Quality Estimate) in each uplink frame. After the uplink frame having the best QE is selected by comparing) fields, TB blocks in which the CRCI indicator is normal are selected and copied to the combination buffer 35 within the selected uplink frame.

In more detail, first, the IMT-2000 vocoder 30 searches the CRCI field for the first TB block in the uplink frame having the best QE (step S36), and then checks whether the CRCI of the TB block is normal. (Step S37) If the CRCI field is confirmed to be Good, the corresponding TB block is selected and copied to the combination buffer 35 (Step S38). Here, the reason why the QE selects the best uplink frame to search for the CRCI field of the TB block is because the number of CRCIs in the uplink frame with good QE can reduce the search time.

If the CRCI field of the TB block is found to be abnormal in step S37, QE selects the next uplink frame in good order, and then searches for the CRCI field for the corresponding TB block in the corresponding uplink frame ( Step S39), it is checked whether the CRCI for the corresponding TB block is normal (step S40), and the TB block of the uplink frame for which the CRCI field is confirmed normal is selected and copied to the combination buffer 35 (step S38). ).

However, as a result of searching for the CRCI field for the corresponding TB block in all uplink frames in good order (step S41), all the uplink frames stored in each frame buffer 31 to 33 are assigned to the corresponding TB block. If the CRCI field is found to be abnormal, QE selects the TB block of the best frame and copies it to the combination buffer 35 (step S42).

After selecting a specific TB block in the uplink frame and copying it to the combination buffer 35 in the same manner as described above, the remaining TB blocks are selected and copied in the same manner as described above. For this purpose, an IMT-2000 vocoder ( 30) checks whether the currently copied TB block is the last TB block included in the uplink frame (step S43), and if it is not the last TB block, returns to step S36 to determine the next TB block in the uplink frame having the best QE. If the currently copied TB block is the last TB block included in the uplink frame, the TB blocks copied to the combining buffer 35 are combined and transmitted to a higher layer by Step S44), it is possible to provide the best voice quality or data service among the frames received through the respective base stations 11 to 13 during soft handoff. Can select and use frame data.

In addition, the embodiment according to the present invention is not limited to the above, and can be implemented by various alternatives, modifications and changes within the scope obvious to those skilled in the art, soft handoff For the uplink frame of the city, a good quality may be selected and combined even in a dedicated transport channel (DCH) unit including a plurality of TB blocks instead of a TB block unit.

As described above, the present invention selects and combines only high quality TB blocks using QE and CRCI for each TB block included in an uplink frame received through each base station during soft handoff in the IMT-2000 vocoder. As a result, the reliability of the transport layer can be improved.

In addition, the present invention selects and combines only high quality TB blocks in each uplink frame during soft handoff, and transmits them to a higher layer, thereby maintaining system performance by maintaining excellent voice call quality or reducing the number of retransmissions for data services. It can be improved.

Claims (5)

Receiving a plurality of uplink frames through respective base stations in the boundary area where the subscriber station is located and storing them in respective frame buffers during soft handoff; Selecting TB blocks in which the CRCI is normal within the uplink frame having good QE among the uplink frames stored in each frame buffer, and copying them to the combination buffer; And combining each TB block copied to the combining buffer and transmitting the combined TB blocks to a higher layer. The method of claim 1, In the process of selecting and copying TB blocks having the normal CRCI to the combined buffer, the uplink frames are sequentially selected from the uplink frames stored in the respective frame buffers in order of good QE, and then TB blocks having the normal CRCI are selected to select the combined buffer. Copying to; If there is a TB block in which CRCI is abnormally identified in all uplink frames, QE selects TB blocks of the best uplink frame and copies them to the combination buffer. How to select and combine link frame data. The method of claim 1, Sequentially checking a payload checksum of an uplink frame stored in each frame buffer to determine whether an uplink frame having a normal payload exists; Copying the entire uplink frame to the combination buffer when there is an uplink frame having a normal paylog; And transmitting the uplink frame stored in the combining buffer to a higher layer. The method according to any one of claims 1 to 3, The frame buffer is a buffer for temporarily storing one-to-one uplink frames received through each uplink frame path and a different uplink frame path in a boundary area from one subscriber station, uplink of IMT-2000 vocoder. How to select and combine frame data. The method according to any one of claims 1 to 3, The combination buffer is a buffer for copying and combining frame data selected from uplink frames temporarily stored in each frame buffer through different uplink frame paths. How to choose and combine.