JP3060265B2 - BTR phase hold control method - Google Patents

Abstract

PURPOSE:To eliminate too rapid switching of control by controlling a phase hold of BTR in a predetermined timing when the VOX mode of an opposite mobile equipment is detected and the synchronization burst transmission mode is detected. CONSTITUTION:An RSSI level being an output of an RSSI (reception electric field strength) amplifier 2 is measured at three points a, b, c in the VOX timing given externally by a VOX detection circuit 4, and the level is identified based on an externally set threshold level at a comparator 3. As a result, when a difference of a reference level or over is in existence between a level of the point (b) and a level of the points a, c, the VOX detection circuit 4 discriminates it that a mobile equipment being a communication opposite party is in operation in the VOX mode, a BTR hold control section 5 masks an output L/H of the comparator 3 to a BTR section 6 and sends a control signal of a BTR hold in a predetermined timing. Furthermore, too rapid switching of control due to identification results L/H of the RSSI for each symbol is prevented in any case by allowing the BTR hold control section 5 to fetch a designation signal of a received synchronization burst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base station receiver for receiving bursts transmitted from a plurality of mobile stations of a TDMA communication such as a digital automobile radio telephone system to a base station. The present invention relates to a control method for holding a phase of demodulated data for so-called Bit Timing Recovery (BTR) for reproducing a clock having a bit phase. Taking a digital car telephone system as an example, a base station receiver for TDMA communication transmits an uplink synchronization burst to the base station receiver in order to synchronize the frame received from each mobile station with a frame. So-called Voice Operat for low power consumption
ed Transmitter: Receives upstream communication bursts in the VOX operation mode.In each burst, 54 to 118 bits are provided as so-called guard bits (G) at the beginning and end of a plurality of symbols constituting the burst. However, in the base station receiver, the guard bit that originally has no received wave
In order to prevent erroneous synchronization when the interference noise of the same channel is added to the portion (G), ie, loss of synchronization, some means is required. Usually, the mobile station in the base station receiver
The determination of the OX mode is made by receiving a postamble pattern for notifying the VOX operation and a preamble pattern for notifying the end of VOX from the mobile device. However, since the length of these patterns is as large as 224 bits, the number of VOX recognition circuits including error tolerant circuits and the like becomes enormous, and it becomes impossible to satisfy the demands for downsizing base station equipment and reducing power consumption. In addition, the timing of reception in the mode of synchronous burst transmission by the steady procedure is not problematic because it is notified from the network side, but when the base station recognizes out-of-synchronization on the mobile station side during a call with the mobile station. Transmits a synchronization burst at random according to the rules, but the base station has no means to know until the mobile station side receives the synchronization word SW and recognizes the state of the synchronization burst. Therefore, on the base station receiver side,
A BTR that reproduces a bit timing clock from a received burst in a guard bit (G) part of a synchronous burst received from a mobile station during a call so that the above-mentioned erroneous synchronization does not occur.
Therefore, control for holding the bit phase of the demodulated data is required.

[0002]

2. Description of the Related Art Taking a digital car telephone system as an example,
FIG. 4 is a block diagram showing a conventional BDMA phase hold control system in a TDMA communication mode limited to the VOX operation mode of a mobile station, FIG. 5 is a time chart, and FIG. This will be described below. In the configuration diagram of FIG. 4, (7) is a detection circuit for detecting a burst-like IF signal received from each mobile station by the base station receiver and outputting demodulated data of a certain slot, and (8) is a detection circuit for the received burst-like signal. An RSSI amplifier that determines the received field strength RSSI level from the IF signal of (9), the comparator (9) identifies the RSSI level of the output with a threshold of an external setting, and determines whether the required level of RSSI is present H / L, (10) outputs a VOX detection signal indicating that the mobile device is operating in the VOX mode, based on the determination result H / L and VOX timings a, b, and c provided from the outside, and outputs the BTR unit ( In contrast to 11), a control signal for holding a symbol phase of demodulated data in a fixed slot composed of a plurality of symbols output from the detection circuit (7) and reproducing a clock.
(BTR hold). As described above, the conventional phase hold control method of the BTR of the base station receiver uses the RSSI amplifier with the reference threshold value set from the outside.
The RSSI level of the output of (8) is identified for each symbol of the demodulated data of the fixed slot in which the received IF signal is detected, and the control signal of the BTR hold is changed to the BTR (11) only when the identification result is a symbol of "L". ), The BTR hold control for each symbol is performed, and as a result, the BTR hold control shown in FIG.
The control method operates at the timing shown in FIG. Independently of the phase hold control of the BTR, the identification result at the three points a, b, and c of the VOX timing of the external input causes a level difference such as "L", "H", and "L". A circuit was provided to detect that the mobile was operating in VOX mode.

[0003]

In the above-mentioned prior art,
Also, (1) the line condition from the mobile device deteriorates and the
When the RSSI is near the reception sensitivity point, the identification result "L / H" is fluttered near the threshold of the comparator, and the BTR hold in FIG.
The control signal is as shown in (C). Also, (2) there is a problem that there is no correspondence when the operation mode is suddenly switched from the communication burst to the synchronization burst due to the loss of synchronization on the mobile device side during a call. An object of the present invention is to realize a phase hold control method of a BTR that solves the above-mentioned problems of the prior art.

[0004]

SUMMARY OF THE INVENTION The problem of the conventional system described above is that only the identification result of the RSSI level performed for each of a plurality of symbols of the demodulated data of a fixed slot received and detected by the base station receiver is used. Focusing on the fact that this is the only information of the phase hold for the BTR, the basic configuration of the present invention is shown in the principle diagram of FIG. (1) is a reception IF signal detection circuit. (2) RSSI amplifier. (3) is a comparator that identifies the RSSI level based on an externally set threshold. (4) is
In the VOX detection circuit, the difference between the RSSI level at the three points a, b, and c of the VOX timing given from the outside is "L""H""L" and the level is different. Is a circuit that detects that is operating in VOX mode. (6) is the detection circuit 1
A BTR unit that reproduces a clock of the bit phase from the demodulated data of the output of FIG. (1)-(4) (6) are the same as the circuits (7)-(10) (11) of the conventional system described above. Reference numeral (5) denotes a BTR hold control unit. The BTR unit (6) uses the output of the comparator 3, the output of the VOX detection circuit 4, and the input synchronous burst designation signal.
This is a new circuit for generating a control signal for holding the reproduced clock of the bit phase of the output.

[0005]

In the present invention, referring to the time chart of FIG.
The VOX detection circuit 4 measures the RSSI level of the output of the RSSI amplifier 2 at three points (a), (b), and (c) of the externally applied VOX timing, and externally sets the RSSI level with the comparator 3 Is identified by the threshold value. As a result of the identification, when there is a level difference equal to or more than the reference level between the level at the point (b) and the level at the points (a) and (c), the VOX detection circuit 4
When it is determined that the device is operating in the VOX mode, and when it is determined that the device is operating in the VOX mode, the BTR hold control unit 5 sets the BTR unit (6)
In response to this, a control signal for the BTR hold (B) is generated and transmitted at a predetermined timing by masking the output L / H of the comparator 3. As a result, RSSI for each symbol in the second and subsequent bursts from a mobile station operating in VOX mode
Of the identification result "L / H" is prevented. Also, the BTR hold control unit 5 is provided with a designation signal indicating that it is operating in the mode of synchronous burst transmission received from the mobile station of the other party.
(32 in the uplink synchronization burst in the frame configuration diagram of FIG. 3)
Bit SW bit), the second and subsequent bursts of a synchronous burst during a call
It is also possible to prevent flutter due to the RSSI identification result "L / H".

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle diagram of FIG. 1 shows the configuration of an embodiment of the present invention as it is. The detection circuit of (1), the RSSI amplifier of (2), and the BTR section of (6) are circuits provided in the demodulator of the base station receiver for general TDMA communication. The comparator of (3) and the comparator of (4)
The VOX detector and the BTR hold control section of (5) are circuits specific to the present invention. The threshold value of the comparator (3) is set to a level (RSSI level + α) slightly higher than the RSSI level, which is the reception sensitivity point of the demodulator, and is set in each of the fixed slots where a burst received from the mobile station of the other party is detected. For each symbol,
Perform level identification. In the steady state, the RSSI level of the output of the RSSI amplifier (2) is equal to or higher than the above-mentioned threshold value for all symbols, so that the BTR hold control unit (5)
Does not control the BTR phase hold for
The clock is extracted in synchronization with the phase of each symbol of the demodulated data in the fixed slot of the output of (1) and is used as a reproduction clock. Next, a call burst from the mobile device of the other party
So-called Voice Operated Tra for low power consumption of mobile devices
nsmitter: When switching to VOX mode, if the RSSI level is sufficiently high, the result of identification of the output of the comparator (3) "L / H"
Flutter does not occur, but the RSSI level drops and the comparator
When approaching the threshold value of (3), the fluttering may occur. At this time, the VOX detector (4) constantly monitors the level difference between points (b) and (a), and points (b) and (c) of the VOX timing given from the outside, so that Mobile device is VOX
Mode is operating, and the detection result is
It is sent to the TR hold control unit (5). The BTR hold control section (5) outputs the identification output of the comparator (3) from the next burst from the mobile station determined to be in VOX mode to the next burst from the mobile station determined to be in non-VOX mode. By masking L / H and transmitting the BTR phase hold signal (B) to the BTR section (6) at a predetermined guard bit G timing, control flutter is prevented. When the mobile station recognizes out-of-sync during a call and switches to the mode of synchronous burst transmission, the first burst is sent to the comparator (3).
Control by the identification output L / H of the next, and the designated signal of the 32-bit SW bit in the received synchronous burst comes next.
VOX from the next synchronous burst to the communication burst
At a predetermined timing, as when operating in mode
Controls BTR phase hold.

[0007]

As described above, according to the present invention, when the base station receiver detects the VOX mode operation of the partner mobile station by detecting the level difference of the received electric field strength RSSI, and when the received synchronous burst is detected. When the synchronous burst transmission mode is detected by the detection of the designated signal, the BTR phase hold control is performed at a predetermined timing. Otherwise, the BTR phase hold control is performed for each symbol of the received and detected demodulated data of a certain slot. Since the BTR phase hold is controlled based on the judgment result based on the threshold value of the RSSI level that has been performed, simple, small-scale and controllable operation is possible even when all bursts (control, synchronization, communication) of any format are received from the mobile station. The effect of controlling the phase hold of the BTR without flutter can be obtained.

[Brief description of the drawings]

FIG. 1 is a principle diagram showing a basic configuration of a BTR phase hold control method according to the present invention.

FIG. 2 is a time chart for explaining the operation of the embodiment of the present invention.

FIG. 3 is a diagram illustrating a frame configuration of an uplink communication burst and an uplink synchronization burst for explaining the present invention;

FIG. 4 is a configuration diagram of a conventional BTR phase hold control method.

FIG. 5 is a time chart for explaining the operation of the conventional example.

FIG. 6 is a diagram illustrating a frame configuration of an uplink communication burst for explaining a conventional example.

[Explanation of symbols]

1 is a detection circuit, 2 is an RSSI amplifier, 3 is a comparator, 4 is V
An OX detector, 5 is a BTR hold control unit, and 6 is a BTR unit.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 1/38-1/58 H04B 7/26 H04J 3/06 H04Q 7/00-7/38

Claims (1)

(57) [Claims] 1. A base station receiver for receiving each burst transmitted from a plurality of mobile stations in a TDMA communication to a base station. The base station receiver receives and detects (1) each mobile station from a demodulated data of a fixed slot of an output. Control signal (5) for holding the bit phase to a BTR (6) for reproducing a clock synchronized with the bit phase of
In the BTR phase hold control method for transmitting the first field, the base station receiver recognizes the first guard bits of a plurality of symbols of the first burst received from each mobile station and determines the received field strength (RSSI of the output of 2). The comparator (3) performs the operation based on the result of identification (L / H) for each symbol based on the externally set reference threshold. In the second and subsequent bursts, the other mobile unit uses the VOX mode to reduce power consumption. Each operation state is recognized by the detection signal (4) indicating that the mobile station is operating in the specified mode or by the designation signal indicating that the other mobile station is operating in the mode of transmitting the synchronization burst by recognizing the loss of synchronization. A BTR phase hold control method characterized in that a clock synchronized with the bit phase is reproduced at the guard bit position of the burst.