JP2002191068A - Wireless base station unit for mobile communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless base station unit for mobile communication by optimizing a synchronous word retrieval window width of a control channel by each wireless base station so as to relieve a load on synchronization processing of each wireless base station. SOLUTION: The wireless base station unit is provided with a wireless reception section 11 that receives incoming data from a mobile station, an information channel synchronous word retrieval section 12 that retrieves a synchronous word of an incoming information channel to measure a transmission delay, a control channel synchronous word retrieval section 13 that retrieves the synchronous word of the incoming control channel, a time alignment control section 14 that corrects the transmission delay amount, a time alignment control variable storage section 15 that stores a time alignment control variable, a storage section monitor control section 16 that monitors and controls the time alignment control variable storage section 15, and a control channel synchronous word retrieval window width control section 17 that applies variable control to a retrieved window width of the control channel synchronous word retrieval section 13 depending on the time alignment control variable stored in the time alignment control variable storage section 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio base station apparatus for mobile communication, and more particularly, to a transmission delay range in which synchronization can be established when receiving a control signal from a mobile station in a TDMA digital mobile communication system. The present invention relates to a wireless base station device optimized for each wireless zone assigned by the wireless base station.

[0002]

2. Description of the Related Art In a radio base station in a conventional TDMA digital mobile communication system, reception of an uplink control channel from a mobile station is performed as follows. FIG.
It shows the transmission and reception timing of the radio base station and the mobile station,
In the figure, it is assumed that a wireless base station and a mobile station are communicating using slot 0. The reception timing of the radio base station is determined by the transmission timing of the radio base station. In FIG. 4, the reception start timing of slot 1 at the start of transmission of slot 0, the reception start timing of slot 2 at the start of transmission of slot 1, At the start of transmission of slot 2, the reception start timing of slot 0 is reached. The same applies to the following transmission / reception timing.

On the mobile station side, the timing of transmitting an uplink signal to a base station is determined by the timing of receiving a downlink signal from a radio base station.
After receiving the downlink signal, transmission is started at an interval T for a time equal to one slot. Here, as described above, the reception timing of the radio base station and the transmission and reception timing of the mobile station are determined by the transmission timing of the radio base station. Therefore, when the radio base station receives an uplink signal from the mobile station, Due to the transmission delay in the radio section in the downlink direction from the station to the mobile station and in the uplink direction from the mobile station to the radio base station, the uplink signal is delayed by a symbol with respect to the reception timing of the radio base station.

In response to this delay, a PDC (Personal Digi
In the information channel in the mobile communication system of the (tal Sellular) system, the transmission timing of the mobile station is forcibly controlled by an instruction from the radio base station so that the uplink signal arrives at the reception timing of the radio base station, that is, to eliminate the delay. Time alignment control is performed. PDC
The modulation system is a 1 / 4π shift QPSK (4-phase PS
K) and two bits of data are transmitted simultaneously as one symbol, so that the time alignment adjustment range can be transmitted between 0 and 6 symbols earlier than the standard transmission timing of the mobile station. ing.

FIG. 5 shows a data structure of a slot. The slot includes a synchronization word, which is a specific data pattern for synchronizing between the radio base station and the mobile station, and an information section, which is data to be transmitted, and the synchronization word is arranged while the information section is divided. I have. FIG. 6 shows a conventional time alignment control. The wireless base station searches the received data for the presence of the same bit pattern as the synchronization word in data for several symbols before and after the position of the original synchronization word at the reception timing. This range of data to be searched will be referred to as a synchronization word search window.

The range of the synchronization word search window W shown in FIG. 6 is set to be one symbol in the forward direction and six symbols in the backward direction from the above-mentioned time alignment adjustment width from the synchronization word at the reception timing of the radio base station. Good. If the same data pattern as the sync word is found in the sync word search window W, but the data pattern is delayed by b symbols from the reception timing of the radio base station, the radio base station sends Then, the mobile station issues an instruction to advance the transmission of the b symbol, and the mobile station starts the transmission with the transmission timing of the b symbol advanced. Thereby, the radio base station can receive the uplink signal from the mobile station at its own reception timing. Also, if the synchronization word is again before or after the reception timing at the radio base station at the radio base station due to factors such as the mobile station having moved after the previous time alignment adjustment, the transmission timing is similarly transmitted to the mobile station. Direct and adjust.

[0007]

By the way, the control signal is different from the information channel in that the uplink signal is
Random access only when an event occurs,
Since the above-described time alignment control is not performed, the synchronization word detection window W has only to have the same width as the above-mentioned information channel for the control channel of the radio base station.

However, the size of the wireless zone varies depending on the radio wave propagation environment in the wireless zone, the transmission output of the wireless base station, the distance between the wireless base stations in adjacent wireless zones, and the like. That is, while the maximum delay amount of the uplink signal from the mobile station differs for each wireless zone, the fact that the control channel synchronization word search window W has the same width as that of the above-mentioned information channel is the same as that of the wireless base station. It is useless as a process, and there is a problem that having a wide detection width of the synchronization word increases the frequency of occurrence of false recognition synchronization.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and reduces the synchronization processing of a radio base station by optimizing a synchronization word search window width of a control channel for each radio base station. It is an object of the present invention to provide a mobile communication radio base station apparatus capable of suppressing the occurrence frequency of false recognition synchronization.

[0010]

In order to achieve the above object, a mobile communication radio base station apparatus according to the present invention comprises: a radio reception unit for receiving uplink reception data from a mobile station; An information channel synchronization word search unit for searching for a synchronization word of an uplink information channel with the signal of (a) and measuring a transmission delay amount, a control channel synchronization word search unit for searching for a synchronization word of an uplink control channel, and correcting the transmission delay amount A time alignment control unit, a time alignment control amount storage unit that stores a time alignment control value, a storage unit monitoring control unit that monitors and controls the time alignment control amount storage unit, and a time alignment control amount storage unit A control channel for variably controlling a search window width of the control channel synchronization word search unit in accordance with the time alignment control amount being set. Characterized by comprising a Le sync word search window width control unit.

In the present invention, the initial value is set in the time alignment control amount storage unit, and the same initial value is set in the control channel synchronization word search unit by the control channel synchronization word search window width control unit. When the time alignment control occurs in the information channel, the time alignment control unit notifies the storage unit monitoring control unit of the time alignment control amount, and the storage unit monitoring control unit stores the time alignment control amount in the time alignment control amount storage unit. The maximum time alignment control amount is compared, and if the former time alignment control amount is larger than the latter maximum time alignment control amount, the storage unit monitoring control unit is notified to the time alignment control amount storage unit. Rewrite with the time alignment control amount. Thus, under the control of the control channel synchronization word search window width control unit, the control channel synchronization word search window unit changes the synchronization word search window width to the same value as the time alignment control amount. This operation makes it possible to set the synchronization word search window width of the control channel to an optimum value.

A timer is mounted on the storage unit monitoring and control unit. When a time-out occurs, a function of subtracting 1 from the time alignment control amount stored in the time alignment control amount storage unit and a notification from the time alignment control unit are provided. The time alignment control value is compared with the time alignment control amount stored in the time alignment control amount storage unit. If the former is larger, the time alignment control value stored in the time alignment control amount storage unit is compared. And a function of rewriting the amount.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the radio base station apparatus for mobile communication according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram of a mobile communication system.
3 is a wireless base station, 31 to 33 are mobile stations, and 21 to 23 are wireless zones assigned from the wireless base stations 1 to 3, respectively. In the example of FIG. 1, the size of the wireless zone is as follows: wireless zone 21 <wireless zone 22 <wireless zone 23.

The standard transmission and reception timings of the radio base station and the mobile station are as described in FIG. 4, but will be described again. The radio base station and the mobile station perform communication using slot 0, and the reception timing of the radio base station is determined by the transmission timing of the radio base station. , When the transmission of slot 1 is started, the reception start timing of slot 2 is reached, and when the transmission of slot 2 is started, the reception start timing of slot 0 is reached.

Also, on the mobile station side, it is assumed that the transmission timing of the uplink signal to the radio base station is determined by the timing of the reception of the downlink signal from the radio base station, and FIG. Transmission is started at equal intervals. Here, as described above, the reception timing of the radio base station and the transmission / reception timing of the mobile station are determined by the transmission timing of the radio base station.
When the radio base station receives an uplink signal from the mobile station, the radio delay is caused by the transmission delay in the radio section from the radio base station to the mobile station and from the mobile station to the radio base station. It is assumed that the uplink signal is delayed by a symbol from the reception timing of the base station.

FIG. 2 shows a configuration of a radio base station apparatus according to an embodiment of the present invention. This wireless base station device 1
0 indicates a wireless reception unit 11, an information channel synchronization word search unit 12, a control channel synchronization word search unit 13, a time alignment control unit 14, a time alignment control amount storage unit 15, a storage unit monitoring control unit 16, a control channel synchronization word search. The window width control unit 17 is provided.

Radio receiving section 11 receives uplink data from a mobile station, and receives a signal from radio receiving section 11, and information channel synchronization word searching section 12 searches for a synchronization word of an uplink information channel. The symbol a, which is the transmission delay amount shown in FIG. 4, is measured. Time alignment control unit 14
Is for correcting the symbol a, which is the amount of transmission delay in the information channel. The storage unit monitoring control unit 16 monitors and controls the time alignment control amount storage unit 15, and the time alignment control amount storage unit 15 stores the time alignment control value. The control channel synchronization word search window width control unit 17 includes a time alignment control amount storage unit 15
Variably controls the search window width of the control channel synchronization word search unit 13 in accordance with the time alignment control amount stored in the control channel synchronization word search unit 13. The control channel synchronization word search unit 13 searches for a synchronization word of an uplink control channel. .

A timer is mounted on the storage section monitoring and control section 16. When a timeout occurs, a function of subtracting 1 from the time alignment control amount stored in the time alignment control amount storage section 15 is provided. The time alignment control value notified from 14 and the time alignment control amount stored in the time alignment control amount storage unit 15 are compared, and if the former is larger, the time alignment control amount storage unit 15
It has a function to rewrite the time alignment control amount stored in the memory.

Next, the operation of setting the synchronization word search window width of the control channel to the optimum value will be described with reference to the flowchart of FIG. First, when the BTS starts operating (step S1), an initial value is set in the time alignment control amount storage unit 15 (step S2), and accordingly, the control channel synchronization word search window width control unit 17 controls the control channel synchronization. The same initial value is set in the word search unit 13 (step S3). After the setting of step S3 is completed,
The timer in the storage unit monitoring control unit 16 is started (step S4).

Thereafter, when time alignment control occurs in the information channel (step S5),
From the time alignment control unit 14 to the storage unit monitoring control unit 1
6 is notified of the time alignment control amount, and the storage unit monitoring control unit 16 compares this with the maximum time alignment control amount stored in the time alignment control amount storage unit 15 (step S6). When the former time alignment control amount is larger than the latter maximum time alignment control amount in the comparison in step S6 (Y), the storage unit monitoring control unit 16 sends the time notified to the time alignment control amount storage unit 15 to the time. Rewrite with the alignment control amount (step S7). Thus, under the control of the control channel synchronization word search window width control unit 17, the control channel synchronization word search window unit 13 changes the synchronization word search window width to the same value as the time alignment control amount (step S).
8).

When the comparison result in step S6 is not satisfied (N) and the former is equal to the latter (step S9)
In the case of Y), the process returns to step S4, and the timer in the storage monitoring control unit 16 is restarted. That is, in this case, the control channel synchronization word window width is maintained as it is. If step S9 is N, step S5 is performed again.
Return to In step S5, if the time alignment control does not occur (N), the storage unit monitoring control unit 16
Is checked (step S10), and if the timer has not timed out (N in step S10), the process returns to step S5.

In step S10, when the timer times out (Y), the storage unit monitoring control unit 16
It is rewritten to a value obtained by subtracting one symbol from the time alignment control amount in the time alignment control amount storage unit 15 (step S11). Thereby, under the control of the control channel synchronization word search window width control unit 17, the control channel synchronization word search window unit 13 changes the synchronization word search window width to the same value as the time alignment control amount (step S8). The above operation makes it possible to set the synchronization word search window width of the control channel to an optimum value.

Next, it will be described that the synchronization word search window width of the control channel becomes an optimum value depending on the state of the wireless zone. In FIG. 1, the time alignment of the information channel is set to 0 for the wireless zone 21 having the smallest wireless zone due to the radio wave propagation environment or the small transmission output of the wireless base station. This means that the handover to the adjacent wireless zone 22 is performed before the time alignment value = 1 because of the reception level at the mobile station 31 or the like. It can be said that the boundary. At this time, the synchronization word search window width of the control channel becomes equal to the synchronization word.

Next, the wireless zone 22 having the larger wireless zone
, The transmission delay from the mobile station 32 is
Since it is larger than 1, time alignment control occurs, and its maximum value is 2. In this case, the synchronization word search window width of the control channel is +2. Further, in the wireless zone 23 having the largest wireless zone, if the transmission delay from the mobile station 33 is further increased and the maximum time alignment value becomes 4, the synchronization word search window width of the control channel becomes +4.

Here, when the radio base station 2 is stopped due to construction work or the like, and the radio wave from the radio base station 3 is originally located at the position of the radio base station 2 due to overreach, the mobile station is located. If the reception level is valid, the mobile station 3
3 moves to the radio base station 2, the time alignment of the radio base station 3 becomes 6, and the synchronization word search window width of the control channel also becomes +6. It should be noted that in step S6 in FIG. 3, Y may be determined not only once but when a plurality of times have been counted. This can prevent the control channel synchronization word search width from being excessively expanded.

[0026]

As described in detail above, according to the present invention, the time alignment control amount of the information channel
Since the synchronization word search window width of the control channel is adjusted, it can be optimized for each wireless zone assigned by the wireless base station, so that the processing of the wireless base station can be reduced and the frequency of occurrence of false recognition synchronization can be reduced. There is an effect that it can be suppressed.

Furthermore, the synchronous word search window width can be changed so as to follow a change in the size of the corresponding wireless zone when the adjacent wireless base station is stopped due to construction or the like or when an adjacent wireless base station is added. Therefore, even if the state of the wireless zone changes, it is possible to automatically optimize the synchronization word search window width without the intervention of a maintenance person.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a radio base station, a mobile station, and a radio zone in a TDMA mobile communication system.

FIG. 2 is a block diagram illustrating an embodiment of a mobile communication radio base station apparatus according to the present invention.

FIG. 3 is a flowchart showing the operation of the present invention.

FIG. 4 is a diagram showing standard transmission and reception timings of a radio base station and a mobile station in a TDMA mobile communication system.

FIG. 5 is a configuration diagram of slot data in a conventional TDMA mobile communication system.

FIG. 6 is an explanatory diagram of conventional time alignment control.

[Explanation of symbols]

 1 to 3 radio base station 11 radio reception unit 12 information channel synchronization word search unit 13 control channel synchronization word search unit 14 time alignment control unit 15 time alignment control amount storage unit 16 storage unit monitoring control unit 17 control channel synchronization word search window width Control units 21 to 23 Wireless zones 31 to 33 Mobile stations

Claims (2)

[Claims] 1. A radio base station apparatus in a TDMA digital mobile communication system, comprising: a radio reception unit for receiving uplink reception data from a mobile station;
An information channel synchronization word search unit for searching for a synchronization word of an uplink information channel with a signal from the radio reception unit, and measuring a transmission delay amount; a control channel synchronization word search unit for searching for an uplink control channel synchronization word; A time alignment control unit for correcting a transmission delay amount, a time alignment control amount storage unit for storing a time alignment control value, a storage unit monitoring control unit for monitoring and controlling the time alignment control amount storage unit, and the time alignment control And a control channel synchronization word search window width control unit for variably controlling a search window width of the control channel synchronization word search unit according to the time alignment control amount stored in the amount storage unit. Wireless base station device. 2. The storage unit monitoring and control unit includes a timer, and a function of subtracting 1 from a time alignment control amount stored in the time alignment control amount storage unit when a time-out occurs, and a function of the time alignment control. The time alignment control value notified from the unit and the time alignment control amount stored in the time alignment control amount storage unit are compared, and when the former is larger, the time alignment control amount is stored in the time alignment control amount storage unit. 2. The mobile communication radio base station apparatus according to claim 1, further comprising a function of rewriting a time alignment control amount.