JP2972084B2 - TDMA mobile radio equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a TDMA (Time Divis
The present invention relates to a mobile radio apparatus of an ion multiple access (time division multiplex access) system.

[0002]

2. Description of the Related Art In a radio communication system of the TDMA system, when a mobile radio station is used in a communication area of a base station, a burst signal transmitted from the base station is first transmitted by a receiving section when the radio apparatus is powered on. Upon reception, a unique word in the burst signal is detected, and if the unique word matches the desired one of the mobile radio station, the information of the burst signal is read to find a base station and start communication. did it. However, for example, in a system using a micro cell such as a digital cordless telephone, a communication is attempted with a base station that can first detect a unique word in accordance with the timing, but the station is a mobile radio station. Is not necessarily the shortest distance from the base station. If the base station is not the shortest distance, a burst signal of the shortest distance base station becomes an interference wave, so that it takes time to establish communication with the shortest distance base station. In order to prevent this, first, only the electric field strength is continuously measured over the period equal to or longer than the burst period, and the burst of the base station located at the shortest distance during the period having the electric field strength having the relatively largest absolute value among them is measured. Assuming that there is a slot, a method of detecting a unique word by receiving a burst signal in the next burst cycle has been proposed.

[0003]

However, in the case of such a method, there is a problem that the measurement of the electric field intensity must be continued for at least one burst period or more, so that the start of communication is delayed. Therefore, an object of the present invention is to provide a mobile radio apparatus of the TDMA system which can start actual communication relatively quickly after the apparatus is turned on.

[0004]

SUMMARY OF THE INVENTION A wireless communication system according to the present invention.
In a TDMA wireless communication system, a burst signal emitted from a base station at a predetermined cycle is detected from a received signal, data in the burst signal is read based on the detected burst signal, and then bidirectional communication is performed. a mobile wireless device to start, and the electric field strength detecting means for detecting an electric field strength of a received signal, after power to the mobile radio device
First Accordingly field strength detection value in the field strength detection means first
A first discriminating means for setting a point in time when it is detected that the value is equal to or more than a predetermined value as a burst signal detection point.

[0005]

In the mobile radio apparatus of the TDMA system of the present invention, the electric field strength of the received signal is detected and the electric power to the mobile radio apparatus is detected.
When the electric field strength detection value is greater than or equal to the first predetermined value for the first time after the power is turned on, the burst signal detection time is set, and based on the burst signal detection time, data such as a unique word in the burst signal is read, and then bidirectional communication is performed. Be started.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the receiving section of the TDMA mobile radio apparatus shown in FIG. 1, a signal received from an antenna 1 is amplified by a low noise amplifier (LNA) 2 and then supplied to a mixer 3. The mixer 3 mixes the received signal with the first oscillation signal from the first local oscillator 4 to generate an intermediate frequency signal. Intermediate frequency signal is AGC (automatic gain control)
The signal is supplied to one input terminal of the two mixers 6 and 7 via the amplifier 5.

The second input terminal of the mixer 6 is directly supplied with a second oscillation signal for demodulation having a predetermined frequency and emitted from a second local oscillator 8. A signal obtained by shifting the phase of the second oscillation signal by 90 ° by the phase shifter 9 is supplied to the other input terminal of the mixer 7. Accordingly, the in-phase component in the received signal is detected by the mixer 6, and the quadrature component is detected by the mixer 7. The output signal of the mixer 6 is an A / D converter 10
, And as an I (In-phase) channel data, the detection output signal of the mixer 7 passes through an A / D converter 11 and Q (Quadrature).
Each is transferred to a DSP (Digital Signal Processor) 12 as channel data. The DSP 12 is controlled by a microcomputer (not shown).
After compensating for the phase amplitude of the data, the data is determined, serially converted, and output to the D / A converter 13 as received data. The D / A converter 13 converts audio data in the received data into analog data.

The electric field intensity of the intermediate frequency signal output from the mixer 3 is detected by a level detector 14, and the output signal of the level detector 14 is supplied to the DSP 12 as digital data. In such a mobile radio apparatus system, for example, in a time slot allocated from a base station, the transmission output of the transmission unit is increased at a predetermined timing as shown in a waveform in FIG. 2 and is decreased after a predetermined time. . In FIG. 2, a quadruple TDM
A shows the A system, and transmission and reception are alternately performed between the base station and the mobile station at each position having the same slot number such as slot number 1.

In a control channel used for communication between a base station and a mobile station, slots are configured as shown in FIG. 3 in the case of a quadruple TDMA system. That is, downlink slots 1-4 from the cell-based base station (CS) to the mobile station and uplink slots 1 from the mobile station to the base station.
4 form one TDMA frame, and the TDMA frame consists of 5 msec. The length in which the TDMA frame is repeated for n frames is the downlink intermittent transmission cycle, that is, the burst cycle. The uplink logical control channel is each TD
It is configured by collecting the first slot in the upstream of the MA frame. The downlink logical control channel carries a downlink burst signal of the first TDMA frame in each downlink intermittent transmission cycle.
Slots (burst slots) are collected, and LC
It is called a CH superframe. FIG. 4 shows a configuration example of the LCCH superframe. Here, BC is a broadcast channel, P1 to P6 are paging channels, and SC is an individual cell channel. Also, n _SG = 2 and n _SUB =
4, n _PCH = 3, n _GROUP = 2. Each channel has a data format in the order of a ramp at the rising edge of the transmission, a unique word serving as a synchronization signal, control data, a CRC (cyclic redundancy check) for error detection, communication data, and a ramp at the falling edge of the transmission.

When power is supplied to the above-mentioned mobile radio apparatus, communication is started in the procedure shown in FIG. That is, the DSP 12 starts an operation of detecting a burst signal as described later (step S1). When the burst signal can be detected, the logical control channel LCC
H can read the broadcast channel B including the information on the channel structure and the system information.
The CCH is read (step S2), and the paging channel PiCH and off-hook (OFF HOOK) are monitored (step S3). Thereafter, a link channel is established (step S4), a service channel is established (step S5), and communication is actually started (step S4).
6). During this communication, it is monitored whether or not there is interference from another station (step S7). If there is no interference, it is determined whether or not the communication is on-hook (ON HOOK) (step S8). If the communication is off hook, the process returns to step S7. If it is on-hook, the process returns to step S3.

A link channel is a channel having a quality capacity necessary for call connection of each service using a control channel function. A service channel is a service channel for providing a service using the link channel function. The channel has the required capacity. If there is interference in step S7, another usable communication channel is found (step S9), and the communication channel is avoided (step S10), and thereafter, the process proceeds to step S8.

In the burst signal detecting operation, as shown in FIG. 6, the DSP 12 reads a reference electric field intensity value AVE stored in advance in an internal memory (not shown) (step S11) and is supplied from the level detector 14. The obtained electric field intensity signal is taken as an actually measured electric field intensity value EMF (step S12). From the reference electric field intensity value AVE and the measured electric field intensity value EMF, a reception electric field intensity detection value LEVEL is calculated from the following equation (step S13).

[0013]

LEVEL = (| EMF | / AVE) ² (1) By calculating the received electric field strength detection value LEVEL as described above, the influence of fading can be obtained when a plurality of base stations are almost equidistant. This prevents an error in the selection of the base station at times.

When the received electric field strength detection value LEVEL is obtained,
It is determined whether or not the received electric field strength detection value LEVEL is equal to or more than the upper limit value MAX (step S14). LEVE
If L ≧ MAX, the reception signal at the time when the electric field strength is obtained is regarded as the burst slot time, and the time t at the time of measuring the reception electric field strength detection value LEVEL is stored as the time point t _sot (step S15). The time t is an elapsed time from the time when the power is turned on. The time point t _sot is a time point when the base station transmits the burst signal. On the other hand, if LEVEL <MAX, it is considered that the mobile station exists at an intermediate position between the two base stations. In this case, the reception electric field strength detection value LE
It is determined whether or not VEL is greater than the maximum value 0LEVEL (step S16). The maximum value 0LEVEL is the maximum value of the reception electric field strength detection value LEVEL calculated so far, and the initial value is 0. If LEVEL ≦ 0 LEVEL, it is determined whether or not the time t when measuring the reception electric field strength detection value LEVEL is longer than one burst cycle (step S17).

If LEVEL> 0LEVEL, the received electric field strength detection value LEVEL at this time is set to a new maximum value 0L.
It is updated as EVEL (step S18), and thereafter, the process proceeds to step S17. If the time t when measuring the received electric field strength detection value LEVEL is equal to or shorter than one burst cycle in step S17, the process proceeds to step S12 and the above operation is repeated. On the other hand, the reception electric field strength detection value LEVEL
If the time t at the time of measuring L is longer than one burst period, it means that a received signal satisfying LEVEL ≧ MAX could not be obtained despite measuring the electric field strength longer than one burst period. Therefore, the DSP 12 sets the maximum value to 0 LEV.
It is determined whether or not EL is smaller than the lower limit value MIN (step S19). If 0LEVEL <MIN, only the received electric field intensity detection value LEVEL smaller than the lower limit value MIN was detected during the electric field intensity measurement period, and the communication area flag is set as the distance is too long for communication with the base station. (Step S20). If the out-of-communication area flag is set, communication is not possible.
For example, this is displayed on the display. 0LEVEL
If ≧ MIN, the time t when measuring the maximum value 0LEVEL
_Is stored as the burst signal transmission time point t _sot of the base station (step S21). Note that the upper limit value MAX and the lower limit value M
IN is stored in the internal memory in advance.

When the time t is stored as described above,
As shown in FIG. 7, based on time t, a data signal is detected at the timing of a unique word included in the transmission wave of the base station (step S22), and it is determined whether or not the detected signal matches a predetermined unique word. (Step S2
3). If it is determined that the unique words match, the process proceeds to step S2 shown in FIG. 5 to perform communication. However, if a unique word match cannot be detected, it is determined whether a predetermined time including a burst slot has elapsed (step S24). If the predetermined time has not elapsed, the process returns to step S22, and if the predetermined time has elapsed, this routine ends.

In the case of being far from any base station, even if the absolute value of the electric field strength is relatively large, the absolute value of the absolute electric field strength is small, so that the burst signal cannot be accurately detected. If this is repeated several times, it is consequently determined to be out of the communication area. However, in the device according to the present invention, 0LEVEL ≧ MI
If N, the time t when the maximum value 0LEVEL is measured is stored as the burst signal transmission time t _sot of the base station.
The possibility of erroneously discriminating outside the communication area is reduced.

When the out-of-communication-area flag is set in step S20 or when it is determined in step S24 that a predetermined time has elapsed, the process returns to step S1 and the above-described operation is repeated. Also,
Although the initial value of the reference electric field strength value AVE is stored in the internal memory in advance, the average value is calculated every time the electric field strength is detected, and the reference electric field strength value AVE in the internal memory is updated.

Further, the repetition cycle of the above-mentioned routine is set so that the electric field intensity is detected twice or three times in one time slot.

[0020]

As described above, in the mobile radio apparatus of the TDMA system according to the present invention, the electric field strength of the received signal is detected.
When the electric field strength detection value is equal to or more than the first predetermined value for the first time after the power is supplied to the mobile radio apparatus, the burst signal detection time is set. Even if the measurement is not continued, the bidirectional communication can be started after reading the data such as the unique word based on the burst signal detection time. Further, when the burst signal detection time point is detected, the subsequent measurement of the electric field strength can be stopped.
By placing the device in a so-called sleep mode until the next reception, power consumption can be reduced as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a receiving unit of a mobile wireless device according to the present invention.

FIG. 2 is a diagram illustrating an example of output power control in a TDMA system.

FIG. 3 is a diagram showing an arrangement relationship of slots in a TDMA mobile radio system.

FIG. 4 is a diagram illustrating a structure of an LCCH superframe.

FIG. 5 is a flowchart showing an operation procedure from power-on to communication start.

FIG. 6 is a flowchart showing a burst signal detection operation.

FIG. 7 is a flowchart showing a continuation of the operation in FIG. 6;

[Description of Signs of Main Parts]

 DESCRIPTION OF SYMBOLS 1 Antenna 3,6,7 Mixer 4,8 Local oscillator 12 DSP 14 Level detector

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-222224 (JP, A) JP-A-5-244085 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04Q 7/00-7/38 H04B 7/24-7/26 102

Claims (8)

(57) [Claims] In a wireless communication system of the TDMA system, a burst signal emitted from a base station at a predetermined cycle is detected from a received signal, and data in the burst signal is read based on the detected burst signal and both data are read. Direction
A mobile wireless device to initiate the communication, and the electric field strength detecting means for detecting an electric field strength of the received signal, the moving electric field strength detection value of the first for the first time the field strength detecting means after power to the wireless device It is more than a predetermined value
It mobile radio device, wherein a and a first determination means to the burst signal detection time point when it is detected. 2. A cycle detecting means for detecting a period until the predetermined cycle elapses from the start of the electric field strength detecting operation of the electric field strength detecting means, and the elapse of the predetermined cycle is detected by the cycle detecting means. A maximum value detecting means for detecting a maximum value of the electric field intensity detected by the electric field intensity detecting means during a period until the electric field intensity detecting value is determined to be smaller than the first predetermined value by the first determining means. And determining whether or not the maximum value detected by the maximum value detection means is equal to or greater than a second predetermined value smaller than the first predetermined value when the elapse of the predetermined cycle is detected by the cycle detection means. A second discriminating means, and if the second discriminating means determines that the maximum value is equal to or greater than the second predetermined value, the electric field intensity detecting means detects when the electric field intensity of the maximum value is detected. Processing means for processing as a burst signal detection time, and when the second determination means determines that the maximum value is smaller than the second predetermined value, processing assuming that the own station is outside the communication area of the base station; The mobile radio device according to claim 1, further comprising: 3. The electric field intensity detecting means obtains an electric field intensity detection value LEVEL from an actually measured electric field intensity value EMF actually measured for the received signal and a reference electric field intensity value AVE, and LEVEL = (| EMF | / AVE) 2. The mobile wireless device according to claim 1, wherein the mobile wireless device is calculated from an equation. 4. The apparatus according to claim 3, wherein said electric field intensity detecting means has a memory in which said reference electric field intensity value is stored in advance, and is updated by an average value of the sequentially calculated electric field intensity detection values. Mobile radio device. 5. The electric field strength detecting means detects electric field strength at a predetermined detection cycle, and the predetermined detection cycle is set so that the electric field strength is detected twice or three times in one time slot. The mobile radio device according to claim 1, wherein: 6. The mobile radio apparatus according to claim 1, wherein said electric field strength detecting means starts an electric field strength detecting operation in response to power-on of said apparatus. 7. A method according to claim 7, further comprising a third determining means for detecting a unique word from the burst signal when the burst signal detection time point is detected, and determining whether or not the unique word matches the unique word of the own station. The mobile wireless device according to claim 1, wherein 8. The mobile radio apparatus according to claim 7, wherein when the third discriminating means does not discriminate the coincidence of the unique words within a predetermined time, the burst signal detection time is newly detected.