KR20050080323A - Method for increasing received signal quality of mobile communication terminal - Google Patents

Abstract

The present invention provides a first process of receiving, by a base station, received signal quality information indicating a reception sensitivity of a mobile communication terminal through a slow coupled control channel, a second process of comparing the received signal quality information with a preset handover reference value, and a received signal. A third step of determining whether the handover is possible if the quality information is lower than the handover threshold value; a fourth step of allocating a remaining frame as an error prevention data frame by reducing the voice data of the traffic channel frame if the handover is impossible; And a fifth step of generating error protection data by error preventing coding, and transmitting the generated error protection data to the allocated error protection data frame to the mobile communication terminal. Accordingly, the present invention provides a method for increasing the reception sensitivity of a mobile communication terminal in a situation where a handover cannot be performed due to a decrease in reliability of a signal received by the mobile communication terminal, thereby reducing noise and mute, thereby reducing call quality. Improve the number of calls and reduce the number of call drops.

Description

METHOD FOR INCREASING RECEIVED SIGNAL QUALITY OF MOBILE COMMUNICATION TERMINAL}

The present invention relates to a method for increasing reception sensitivity of a mobile communication terminal. In particular, a base station can perform handover for increasing reception signal sensitivity of a time division multiple access (TDMA) type mobile communication terminal. It relates to a method of increasing the received signal sensitivity of the mobile communication terminal when there is no.

The development of mobile communication has been developed into the second generation digital method through the so-called first-generation analog method (FDMA: Frequency Division Multiple Access), and the second generation mobile communication is TDMA method (Europe, China, USA) Some) and Code Division Multiple Access (CDMA) methods (Asia / Pacific region such as the US, Korea, Australia). Since then, the global market has been divided into two major camps: Global System For Mobile Communication (GSM) based in Europe / Japan (W-CDMA: Wideband-CDMA) and US-based synchronous method (CDMA2000). And development is in progress.

Looking specifically at TDMA, TDMA divides a given frequency band (mostly much wider than a FDMA channel band) periodically at regular time intervals, and transmits its own signal for each user in order. The receiving side may also receive the reception information only during the corresponding time. This time interval is called a time slot, and uses a time gate to receive its information. In other words, if the total data rate that can be sent to a specific transmission channel is 100kbps, a voice signal usually needs a transmission speed of about 20kbps. Therefore, five 20kbps signals are sequentially transmitted to this 100kbps signal, and then another five data signals are transmitted. . This means that each user transmits and receives only the 20kbps signal needed for each user's own call.However, when using a wireless channel, the 100kbps channel is divided into 5 time slots, and each user occupies one time slot to transmit data. will be. In the TDMA method, each voice channel is a time slot, so in order to increase the number of voice channels, the time slot must be increased. When the time slot is increased, each transmission channel must be widened. Therefore, it is important to appropriately determine the RF transmission channel bandwidth and the number of time slots. .

1 is a configuration diagram of a TDMA mobile communication system. The mobile communication system shown in FIG. 1 includes a first mobile communication terminal (MS) 10, a second mobile communication terminal 12, base transceiver stations (BTS) 20 and 22, and a base station controller. (BSC: Base Station Controller) 30, Mobile Telephone Switching Center (MSC) 40, and Service Node 50 (SN: Service Node).

Base stations 20 and 22 are connected to base station controller 30. The base stations 20 and 22 are wirelessly connected to the first mobile communication terminal 10 and the second mobile communication terminal 12 in the cell areas C1 and C2 to provide mobile communication services.

The base station controller 30 is connected to the mobile communication exchange 40, and the service node 50 is connected to the mobile communication exchange 40 to support a predetermined service for the mobile communication system.

As shown in FIG. 1, since the first mobile communication terminal 10 is located in the cell C1 and the second mobile communication terminal 12 is located in the cell C2, the BTS 20 of the cell C1 and the BTS 22 of the cell C2 are illustrated. Provides a mobile communication service to the first mobile communication terminal 10 and the second mobile communication terminal 12 through a predetermined wireless channel according to the TDMA scheme.

Meanwhile, the channel usage method in GSM is used by mapping a logical channel to a physical channel such as an RF channel, a TDMA frame, a time slot, etc. The types of logical channels include a traffic channel (TCH) and Control channels (BCCH, PCH, RACH, SACCH, FACCH) and the like. Information such as voice and data is transmitted through the traffic channel, and control signals between the base station and a plurality of mobile communication terminals are transmitted through common control channels such as BCCH, PCH, and RACH among control channels. Here, SACCH (Slow Associated Control Channel) is a channel used for transmitting and receiving control information between one base station and one mobile communication terminal and is a logical channel used for transmitting and receiving system information and Mobile Assisted Handoff (MAHO). .

The SACCH is used in conjunction with a traffic channel, and the mobile communication terminal uses the uplink SACCH to communicate with the base station through the uplink SACCH, the received signal quality information received by the mobile communication terminal, and a logical channel set of links used for synchronization with an adjacent cell. Broadcast Channels (BCH) Power transmits power measurement information and the like. The downlink SACCH of the base station includes transmission signal power information of the mobile communication terminal, timing flow information of the mobile communication terminal, and channel configuration information of the cell. As described above, the SACCH plays an important role in controlling the radio link. Therefore, when a message containing information transmitted and received through the SACCH error occurs continuously, the wireless link can be adversely affected by other mobile communication terminals, so the connection is blocked. In this case, whether the radio link is blocked may be determined by the base station or the mobile communication terminal. The criterion for determining whether the radio link is blocked in the mobile communication terminal depends on the rate of successfully decoding the downlink SACCH message. The criterion for determining whether the radio link is blocked in the base station is the error rate of the uplink SACCH and the mobile communication. It depends on the quality of the received signal measured at the terminal. However, since SACCH has a strong error correction capability, the probability of error is very low, and thus the quality of a received signal is degraded by traffic channels used in combination with SACCH.

The base station performs a handover to change the call signal to another base station when the quality of the received signal of the mobile communication terminal deteriorates. However, if there is no base station capable of handover in the vicinity, the signal received by the mobile communication terminal may be muted with noise or voice ( Mute) will occur.

Accordingly, an object of the present invention is to provide a method of increasing reception sensitivity for improving call quality in a TDMA mobile communication terminal.

Another object of the present invention is to provide a method for increasing the reception sensitivity of a mobile communication terminal in a situation where it is impossible to perform a handover for increasing the sensitivity of the reception signal of the mobile communication terminal when the connection of the radio link is maintained by the SACCH.

In order to achieve the above object, the present invention provides a method for increasing the reception sensitivity of a mobile communication terminal in a time division multiple access type mobile communication system in which a low speed combined control channel used in combination with a traffic channel controls a radio link between a base station and a mobile communication terminal. A first process of receiving, by the base station, received signal quality information indicating the reception sensitivity of the mobile communication terminal through the slow coupled control channel; and a second process of comparing the received signal quality information with a preset handover reference value; And a third step of determining whether handover is possible when the received signal quality information is lower than the handover reference value, and if the handover is impossible as a result of the determination, a frame that reduces voice data of the traffic channel frame as an error prevention data frame. A fourth process of allocating the voice data; Characterized in that it comprises a sixth step of transmitting the fifth process and the put the error protection data generated in the allocated error protection data frame, the mobile terminal generates an error protection encoding data.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are represented by the same numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

2 is a flowchart illustrating an operation performed by a base station to increase a reception sensitivity of a mobile communication terminal.

Referring to FIG. 2, the base station receives reception signal quality information indicating the reception sensitivity of the mobile communication terminal transmitted by the mobile communication terminal through the uplink SACCH (S110).

The base station compares the received received signal quality information with a preset handover reference value to perform the handover (S120).

If the received signal quality information is lower than the handover reference value, the base station determines whether handover is possible (S130).

If the base station determines that handover is possible, the base station performs handover (S170). If the handover is impossible, the base station allocates a frame that reduces voice data of the traffic channel frame combined with the SACCH as an error prevention data frame (S140). . When the voice data of the traffic channel frame is reduced in step S140, it is preferable to reduce the full rate voice data corresponding to one frame by half using half rate voice coding. That is, if the amount of speech data at full rate speech coding for predetermined speech data "A" is "100", the amount of speech data at half rate speech coding is "100/2". The reason why the voice data is cut in half is that even if the voice data is cut in half, the quality of the signal received from the mobile communication terminal does not make a big difference.

The base station generates error-proof data by error-proof coding the remaining voice data in step S140 (S150). Here, the error protection data is preferably generated using an error protection coding scheme, and the error protection data is data that is interlocked with the voice data cut in half and the reliability (ie, the quality) of the voice data. ) To increase.

The base station transmits the generated error protection data to the mobile communication terminal along with the remaining voice data in the allocated error protection data frame (S160). Accordingly, the mobile communication terminal can receive highly reliable voice data in a state where handover is impossible.

3 is a diagram illustrating a state of a frame that changes according to a process for increasing reception sensitivity of a mobile communication terminal according to an exemplary embodiment of the present invention.

Referring to FIG. 3, reference numeral 210 denotes a structure of a frame in which a traffic channel and a SACCH are combined in full rate voice coding. "T" is a traffic channel frame, "S" is a SACCH frame, and "I" is a frame not used as an idle frame.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16 to 24 voice data in the traffic channel frame, and "12" information in the SACCH frame. Is listed.

Reference numeral 220 denotes a state in which speech data of a traffic channel frame excluding the SACCH frame and the idle frame of reference numeral 210 is cut in half using half rate speech coding according to an embodiment of the present invention. The remaining voice data in the traffic channel frame is 0, 2, 4, 6, 8, 10, 13, 15, 17, 19, 21 and 23, and the hatched frame is the traffic channel frame left by cutting the voice data in half. For example, the frame allocated to the error prevention data frame.

Reference numeral 230 denotes a state in which error protection data generated by using an error protection coding scheme (Error Protection Coding Scheme) is loaded on the error protection data frame (that is, T '). Error protection data (ie, 0 ', 2', 4 ', 6', 8 ', 10', 13 ', 15', 17 ', 19', 21 'and 23') in the T 'are the remaining voices. As data interlocked with data 0, 2, 4, 6, 8, 10, 13, 15, 17, 19, 21, and 23, it plays a role of enhancing the reliability of the voice data contained in a traffic channel frame. That is, the mobile communication terminal transmits voice data 0, 2, 4, 6, 8, 10, 13, 15, 17, 19, 21, and 23 transmitted by the base station to 1, 3, 5, 7, 8, 10, 13, When receiving with 15, 17, 19, 21 and 23, the error protection data 0 ', 2', 4 ', 6', 8 ', 10', 13 ', 15', received together in the error protection data frame The voice data 1, 3, 5, and 7 that are incorrectly received (ie, low reliability voice data) through 17 ', 19', 21 'and 23' can be received as the original voice data 0, 2, 4 and 6. It can be.

In the above description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined not only by the claims but also by the equivalents of the claims.

As described above, the present invention provides a method for increasing the reception sensitivity of a mobile communication terminal in a situation where a handover cannot be performed due to a decrease in reliability of a signal received by the mobile communication terminal, thereby reducing noise and mute. This improves call quality and reduces call drops.

1 is a configuration diagram of a TDMA mobile communication system.

2 is a flowchart illustrating an operation performed by a base station to increase a reception sensitivity of a mobile communication terminal.

3 is a view showing a state of a frame that changes according to a process for increasing reception sensitivity of a mobile communication terminal according to an embodiment of the present invention.

Claims (3)

In the method of increasing the reception sensitivity of a mobile communication terminal in a time division multiple access type mobile communication system in which a low speed combined control channel used in combination with a traffic channel controls a radio link between a base station and a mobile communication terminal, Receiving, by a base station, received signal quality information indicating the reception sensitivity of the mobile communication terminal through the slow coupled control channel; A second process of comparing the received signal quality information with a preset handover reference value; Determining whether the handover is possible when the received signal quality information is lower than the handover reference value; A fourth step of allocating a frame that reduces voice data of the traffic channel frame as an error prevention data frame when handover is impossible as a result of the determination; A fifth step of generating error protection data by error-proof coding the voice data; And a sixth step of transmitting the generated error protection data to the allocated error protection data frame to the mobile communication terminal. The method of claim 1, wherein the fourth process is And reducing the voice data included in the traffic channel frame in half and allocating the remaining frame as an error prevention data frame. The method of claim 1, wherein the fifth process is And generating the voice data as the error prevention data by using an ERROR PROTECTION CODING SCHEME.