KR0156855B1 - Method for scanning optical channel in cellular terminal device - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

A technique for scanning an optimal channel for transmitting and receiving data in a cellular terminal device.

2. The technical problem to be solved by the invention

When the mobile station transmits and receives data, the communication channel is temporarily recognized as a strong channel due to external influences such as fading and the like, thereby preventing transmission and reception data errors from occurring.

3. Summary of Solution to Invention

In selecting the optimal channel for the control channel in the mobile station, the seven channels are set in the order of the strongest reception level, and then the three channels with the strongest reception level are extracted by selecting the seven channels. During this period, the receiver can always transmit through the channel with the strongest reception level, increasing the success rate of the call.

4. Important uses of the invention

Applied to optimal channel scanning of cellular mobile communication systems.

Description

Optimal Channel Scanning Method in Cellular Terminal Equipment

1 is a block diagram of a cellular terminal device according to the present invention.

2 is an exemplary form of the construction of a cell site in a cellular system.

3 is a call processing flowchart in which the mobile station turns on and proceeds to a standby state.

4 is an optimal channel scan control flowchart according to the present invention.

* Explanation of symbols for main parts of the drawings

10 microprocessor 12 antenna

14: duplexer 16: RF / 1F unit

18: frequency synthesizer 20: RAM

22: pyrom

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellular mobile communication system and, more particularly, to a method for scanning an optimal channel for data transmission and reception in a cellular terminal device (or mobile station).

In general, a channel of a cellular system is composed of a control channel for sending and receiving data only and a voice channel for sending and receiving data and voice, and AMPS (Advanced Mobile Phone Service) defines a method for finding an optimal channel according to the cellular mobile communication standard. Is laying. Channels 333 and 334 are divided into A and B bands, each of which has 21 control channels. In the standard, the total number of channels is set to 666, of which channels 1 to 333 are assigned to band A for the transmission data. The band A divides 313-333 channels, that is, 21 channels into data channels and channels through the remaining 1-312 channels. Therefore, when using the A band, the 21 channels are scanned to find two optimal channel lists, and the data is tuned to the first optimal channel to receive data from the base station. In order to communicate with the mobile station, the mobile station must first transmit and receive necessary data through a control channel. To this end, the mobile station measures the reception level of 21 control channels of the A and B bands given by the cellular system, selects two channels having the best reception level, and receives no data from the channel having the strongest reception level. It then tunes to the selected strong channel and sends data back and forth to the ready state. Therefore, when transmitting and receiving protocol data between a base station and a mobile station in a cellular mobile communication, it is most ideal to transmit and receive through a control channel having the best Receive Signal Strength Indicate. Thus, US Patent No. 4,776, 037, issued on October 4, 1988, discloses a method and apparatus for scanning the two optimal channels. However, the problem at this time is a scan period defined by the Advanced Mobile Phone Service (AMPS), which occurs because the period is defined as 5 minutes. For example, if the vehicle maintaining the optimal channel at the A cell site, i.e., the mobile station moves to the B cell site before the scan period 5 minutes has elapsed, the optimal channel currently maintained is no longer the optimal channel. This doesn't work. If the rescan is performed after 5 minutes, the reception sensitivity of the existing channel will definitely fall, and in severe cases, the reception sensitivity will be low enough to not receive the paging message.

In fact, it is ideal to set the channel scan period in question every second or every minute to ensure that the mobile station tunes to the optimal channel at any time and from any location, but it does not receive data from the base station during the channel scan. Taking too short and too short is not a desirable channel scan method.

In addition, in the current cellular system, 21 control channels are tuned in order, and the two strong channels are selected by measuring the reception level of each channel twice. However, when sampling the change of the reception level caused by external factors such as fading twice and taking a strong one, the measurement is made incorrectly, and the reception level is temporarily strong and is actually read as a channel with a strong reception level. There was a problem that an error occurred.

Accordingly, an object of the present invention is to provide an optimal channel scan method that performs an optimal channel scan so that a data transceiver error does not occur in a mobile communication system.

Another object of the present invention is to provide an optimal channel scanning method capable of preventing a data transmission / reception error by incorrectly recognizing a strong channel temporarily due to an external influence such as fading phenomenon in a mobile communication system.

In order to achieve the above object, the present invention is to select the strongest 7 channels by sampling twice in one channel, and then select the strongest 3 channels by sampling each of these channels several times, and the mobile station performs the channel scan. By using a channel list with a strong reception level, a channel having a strong reception level can be scanned accurately and quickly while moving.

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

1 is a block diagram of a cellular terminal device applied to the present invention in a cellular mobile communication system, and includes a microprocessor 10, an antenna 12, a duplexer 14, an RF / 1F 16, and frequency synthesis. The unit 18, the RAM 20 and the EPROM (20). It should be noted that in FIG. 1, a block diagram of the audio processor is omitted in order not to obscure the present invention.

In the configuration of FIG. 1, the duplexer 14 is a device that protects the receiver from a transmission output when transmitting for the common use of one antenna 12 for transmission and reception and supplies an echo signal to the receiver when receiving. The RF / 1F unit 16 includes a transmitter, a receiver, and an interface unit. The RF / 1F unit 16 outputs the received data to the microprocessor 10 and outputs the transmission data transmitted by the microprocessor 10 to the duplexer 14. The microprocessor 10 controls the entire system and processes data. The microprocessor 10 outputs the transmission data to the transmission terminal Tx, receives the reception data to the reception terminal Rx, and applies the reception sensitivity strength of the predetermined channel to the reception sensitivity strength measurement terminal RSSI. Receive. In addition, the channel control signals CHCONT for scanning a predetermined channel, for example, channel data, a data strobe signal, and a clock signal are output to the frequency synthesizer 18. The frequency synthesizer 18 controls the RF unit in the RF / 1F unit 16 in response to the channel control signals to lock a predetermined channel for transmission and reception.

2 shows an example of the configuration of a cell site in a cellular system.

A feature of the present invention is to select the strongest 7 channels by sampling twice in a channel twice in a mobile communication system, and then select the strongest 3 channels by sampling these channels several times each, and receive level when the mobile station performs channel scan. This strong channel list is used to accurately and quickly scan channels with strong reception levels while moving.

Therefore, in the present invention, first finding seven channels and selecting three channels again, three directional antennas having seven cell sites as one group and 120 ° as another cell site as shown in FIG. This is because it has two and three control channels.

Since the mobile station needs to be tuned to a channel that scans a given control channel to transmit and receive data well, transmission and reception calls are possible, it is important to select a channel as the mobile station moves. A flowchart of call processing in which the mobile station powers on and goes to a standby state is shown in FIG. 3. In operation 101, the microprocessor 10 scans a control channel and receives data in step 102. Check it. If no data is received, the process proceeds to step 103. If the current channel is equal to the next channel, the process returns to step 101. If not, the process returns to step 101. If not, the process proceeds to step 104. However, if data has been received in step 102, the microprocessor 10 proceeds to step 105 and updates to overhead information in step 106. In step 106, the microprocessor 10 scans the paging channel selection and proceeds to step 107. In step 107, the microprocessor 10 checks whether there is a compared channel list. If no channel list is compared, the microprocessor 10 proceeds to step 108 and compares the current channel list with the previous channel list. Then, in step 109, the microprocessor 10 checks whether the electric field strength of the compared current channel and the previous channel is the same as the strongest channel, and returns to step 106 if it is not the same, and proceeds to step 110 if it is equal. Here, in step 107, 108, and 109, the channel list for the strong reception sensitivity value is compared in order to tune to the strongest channel even after moving with the moving state check. If the mobile station continues to grab a channel with a weak reception level and communicates with the mobile station, a data transmission / reception error occurs and the success rate of incoming and outgoing calls is reduced. In step 110, the microprocessor 10 sets the channel having the strongest electric field strength and proceeds to step 111. In step 111, the microprocessor 10 checks whether data has been received. If no data is received, the process proceeds to step 112. If the current channel is equal to the next channel, the process returns to step 101. If not, the process returns to step 101. If not, the process proceeds to step 113. However, if data is received in step 111, the process proceeds to step 114 and the microprocessor 10 proceeds to step 115 after updating the overhead information. In step 115, the microprocessor 10 enters a standby state that can be called and terminates the program.

In the current cellular system, the control channel scan reads the received field strength twice for each channel, compares the values and specifies the two strongest channels, searches for the reception of data through these two channels, and If not, scan the control channel again. The operation of scanning the channel in this way will be described with reference to FIG.

4 is an optimal channel scan control flow chart according to the present invention. The process of setting a channel range for searching for a reception sensitivity strength, and tuning a set channel after setting the channel range for the search, repeatedly repeats the reception sensitivity strength. The process of selecting the seven strongest channels by reading and the process of selecting the three strongest channels by reading the reception sensitivity of the selected channels.

Hereinafter, the operation of the present invention in detail based on the above configuration.

Referring to FIG. 4, in step 120, the microprocessor 10 sets a window range of a channel to search for the received sensitivity strength. In this case, the channel range may be changed according to call progress. Thereafter, in step 121, the microprocessor 10 tunes the set channel and proceeds to step 122. In step 122, the microprocessor 10 repeatedly reads the received sensitivity value twice and proceeds to step 123. In step 123, the microprocessor 10 checks whether the channel scan has ended, and if not, proceeds to step 124. The microprocessor 10 in step 124 tunes the next channel and repeats the above-described operations until the channel scan is completed by repeating steps 122 and 123. Then, in step 125, the microprocessor 10 compares the RSI values of the respective channels, selects seven channels having the strongest RX values in step 126, and proceeds to step 127. In step 127, the microprocessor 10 tunes the selected channel and proceeds to step 128. In step 128, the microprocessor 10 repeatedly reads the received sensitivity value three times and proceeds to step 129. In step 129, the microprocessor 10 checks whether the channel scan has ended, and if not, proceeds to step 130. The 130-stage microprocessor 10 tunes the next channel and repeats the above operations until the channel scan is completed by repeating steps 128 and 129. Then, in step 131, the microprocessor 10 compares RSSI values of the respective channels, selects three channels having the strongest reception sensitivity values, and ends the program in step 132.

As described above, according to the present invention, in selecting the optimal channel for the control channel, the seven channels are set in the order of the strongest reception levels, and the three channels having the strongest reception levels are extracted by searching for the reception levels of the seven channels. In this case, it is possible to transmit / receive through the channel having the strongest reception level even during the movement, thereby increasing the success rate of the call, and also preventing the error of the data transmitted / received by the strong channel temporarily due to fading phenomenon.

Claims (2)

In a cellular mobile communication system for scanning an optimal channel, a process of setting a channel range for searching a reception sensitivity strength, a channel range for the search is set, and then tuning the set channel to repeat the reception sensitivity strength. And selecting the seven strongest channels by reading the data, and selecting the three most optimal channels by reading the reception sensitivity strengths of the selected channels. A method for scanning an optimal channel of a cellular terminal device in a cellular mobile communication system, the method comprising: setting a channel range for searching for reception sensitivity strength, sequentially tuning the set black channel, and in the tuning process A process of repeatedly reading the received sensitivity strengths of the sequentially tuned channels twice, a process of selecting seven channels having the strongest received sensitivity strengths by comparing the received sensitivity strengths of the sequentially tuned channels, respectively; Sequentially tuning the selected seven channels, repeatedly reading the received sensitivity strengths of the tuned seven channels, and comparing the received sensitivity strength values for the read seven channels, respectively. Optimal channel scanning method comprising the process of selecting the strongest three optimal channels.