JPH088808A - Mobile radio equipment adopting tdma system - Google Patents

Abstract

PURPOSE:To start actual communication comparatively earlier after application of power to the equipment by using an electric field strength detected by an electric field strength detection means as a burst signal detecting point of time when the detected level is a prescribed 1st level or over. CONSTITUTION:An electric field strength of an intermediate frequency signal outputted from a mixer 3 is detected by a level detector 14 and an output signal of the level detector 14 is fed to a DSP 12 as digital data. The DSP 12 reads a reference electric field strength stored in advance in its internal memory and fetches the electric field strength signal fed from the level detector 14 as an actually measured electric field strength. The DSP 12 obtains a reception electric field strength detected level LEVEL based on the reference electric field strength and the actually measured electric field strength, and discriminates whether or not the received electric field strength level LEVEL is an upper limit level MAX and uses a reception signal at a point of time when the electric field strength is obtained in the case of LEVEL>=MAX for a signal at a burst slot and stores the time when the received electric field strength level LEVEL is measures as a burst signal detection point of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to TDMA (Time Divis).
ion multiple access: time division multiplexing connection).

[0002]

2. Description of the Related Art In a TDMA type wireless communication system, when a mobile wireless station is used in a base station communication area, first, a burst signal sent from the base station is transmitted from a base station at the time of power-on of the wireless device. Upon reception, the unique word in the burst signal is detected, and if the unique word matches the one desired by the mobile radio station, the information in the burst signal can be read to discover the base station and start communication. did it. However, for example, in a system using a micro cell such as a digital cordless telephone, it tries to start communication according to the timing with a base station that can first detect a unique word, but that station is a mobile radio station. Is not necessarily the base station in the shortest distance from. If it is not the shortest distance base station, the burst signal of the shortest distance base station becomes an interfering radio 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 for a period equal to or longer than the burst period, and the burst of the base station located at the shortest distance in the period in which the electric field strength has the largest relative absolute value. A method has been proposed in which, assuming that there is a slot, a burst signal is received in the next burst cycle to detect a unique word.

[0003]

However, in the case of such a method, there is a problem that the electric field strength has to be continuously measured for at least one burst period or more and the start of communication is delayed. Therefore, an object of the present invention is to provide a TDMA type mobile radio device capable of starting actual communication relatively early after power-on of the device.

[0004]

A TDMA mobile radio apparatus according to the present invention detects a burst signal emitted from a base station in a predetermined cycle from a received signal and detects a burst signal based on the burst signal detection time. A mobile radio device which starts communication after reading the data of 1., and an electric field strength detecting means for detecting electric field strength of a received signal, and an electric field strength detection value by the electric field strength detecting means is equal to or more than a first predetermined value. It is characterized in that it is provided with a first discriminating means for making a burst signal detection time point.

[0005]

In the TDMA mobile radio apparatus of the present invention, the electric field strength of the received signal is detected, and when the electric field strength detection value is not less than the first predetermined value, the burst signal detection time is set, and the burst signal detection time is set as the burst signal detection time. Communication is started after the data such as the unique word in the burst signal is read based on the basis.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. In the receiving section of the TDMA mobile radio apparatus shown in FIG. 1, the received signal from the antenna 1 is amplified by the low noise amplifier (LNA) 2 and then supplied to the 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)
It is supplied to one input end of the two mixers 6 and 7 via the amplifier 5.

A second oscillating signal for demodulation having a predetermined frequency, which is emitted from the second local oscillator 8, is directly supplied to the other input terminal of the mixer 6. A signal obtained by phase-shifting the second oscillation signal by 90 ° is supplied to the other input terminal of the mixer 7 by the phase shifter 9. Therefore, the mixer 6 detects the in-phase component in the received signal, and the mixer 7 detects the quadrature component. The output signal of the mixer 6 is the A / D converter 10
As I (In-phase) channel data, the detection output signal of the mixer 7 passes through the A / D converter 11 and Q (Quadrature).
The data is transferred to the DSP (Digital Signal Processor) 12 as channel data. The DSP 12 is controlled by a microcomputer (not shown), and I, Q
After compensating the phase amplitude of the data, data determination is performed, serial conversion is performed, and the received data is output to the D / A converter 13. The D / A converter 13 converts the voice data in the received data into analog data.

The electric field strength of the intermediate frequency signal output from the mixer 3 is detected by the 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 device system, for example, in a time slot assigned from a base station, the transmission output of the transmission unit is increased at a predetermined timing and decreased after a predetermined time as shown in the waveform of FIG. . In FIG. 2, four-fold TDM
In the A system, transmission and reception are alternately performed between the base station and the mobile station at each position where the slot numbers are the same, such as slot number 1.

In the control channel used for communication between the base station and the mobile station, in the case of the quadruple TDMA system, slots are formed as shown in FIG. That is, downlink slots 1 to 4 from the cell type base station (CS) to the mobile station and uplink slot 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. Uplink logical control channel is each TD
It is configured by collecting the first upstream slots of the MA frame. The downlink logical control channel is the first burst signal for the downlink of the first TDMA frame in each downlink intermittent transmission cycle.
It is composed by collecting slots (burst slots), 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, n _SUB =
This is an example in the case of 4, n _PCH = 3, n _GROUP = 2. In each channel, a data format is configured in the order of a ramp at the transmission rising edge, 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 transmission falling edge.

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

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

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

[0013]

[Equation 1] LEVEL = (| EMF | / AVE) ² (1) By calculating the received electric field strength detection value LEVEL in this way, the influence of fading can be obtained when a plurality of base stations are substantially equidistant. This sometimes prevents the selection of the base station from being erroneous.

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 greater than or equal to the upper limit value MAX (step S14). LEVE
If L ≧ MAX, the received signal at the time when the electric field strength is obtained is regarded as a burst slot, and the time t at the time of measuring the received electric field strength detection value LEVEL is stored as the time point t _sot (step S15). Time t is the elapsed time from the time when the power was turned on. Time point t _sot is the 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 received electric field strength detection value LE
It is determined whether VEL is larger than the maximum value 0LEVEL (step S16). The maximum value 0LEVEL is the maximum value of the received 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 at the time of measuring the received electric field strength detection value LEVEL is longer than one burst period (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 then the process proceeds to step S17. When the time t at the time of measuring the received electric field strength detection value LEVEL is equal to or less than one burst period in step S17, the process proceeds to step S12 and the above operation is repeated. On the other hand, the received electric field strength detection value LEVE
If the time t at the time of measuring L is longer than one burst period, it means that the received signal that satisfies LEVEL ≧ MAX could not be obtained even though the electric field strength was measured longer than one burst period. Therefore, the DSP 12 has a maximum value of 0 LEV.
It is determined whether EL is smaller than the lower limit value MIN (step S19). If 0LEVEL <MIN, only the received electric field strength detection value LEVEL that is smaller than the lower limit value MIN can be detected during the electric field strength measurement period. Therefore, the communication area flag is set to be too far for communication with the base station. Yes (step S20). If the out-of-communication area flag is set, you cannot communicate, so
For example, this is displayed on the display. 0LEVEL
If MIN, the time t at the time of measuring the maximum value 0 LEVEL
_Is stored as the burst signal transmission time t _sot of the base station (step S21). The upper limit value MAX and the lower limit value M
IN is previously stored in the internal memory.

When the time t is stored in this way,
As shown in FIG. 7, the data signal is detected at the timing of the unique word included in the transmission wave of the base station based on the time t (step S22), and it is determined whether or not the detected signal matches the predetermined unique word. Yes (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 or not a predetermined time including the 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.

When it is far from any base station, the burst signal cannot be accurately detected because the absolute value of the absolute electric field strength is small even if the absolute value of the electric field strength is relatively large. If this is repeated several times, it will eventually be determined to be outside the communication area, but in the device according to the present invention, 0LEVEL ≧ MI in step S21.
If N, the time t at the time of measuring the maximum value 0 _LEVEL is stored as the burst signal transmission time t _sot of the base station.
The possibility of erroneously distinguishing from the communication area is reduced.

When the outside-communication-area flag is set in step S20 or when it is determined in step S24 that the 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 advance in the internal memory, the reference electric field strength value AVE in the internal memory is updated by taking an average value every time the electric field strength is detected.

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

[0020]

As described above, in the TDMA mobile radio apparatus of the present invention, the electric field strength of the received signal is detected,
Since the burst signal is detected when the electric field strength detection value is equal to or larger than the first predetermined value, if the electric field strength exists in the communication area, the electric field strength must be continuously measured for a period of one burst cycle or more. Communication can be started after reading data such as a unique word based on the burst signal detection time. Further, when the burst signal detection time point is detected, the measurement of the electric field strength after that can be stopped. Therefore, the power consumption can be reduced more than before by putting the apparatus in the so-called sleep mode until the next reception. Can be planned.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an example of output power control of the TDMA method.

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

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

FIG. 5 is a flowchart showing an operation procedure after power-on until communication start.

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

FIG. 7 is a flowchart showing a part following the operation shown in FIG. 6;

[Explanation of symbols for main parts]

 1 Antenna 3,6,7 Mixer 4,8 Local Oscillator 12 DSP 14 Level Detector

Claims (8)

[Claims] 1. In a TDMA wireless communication system, a burst signal emitted from a base station in a predetermined cycle is detected from a received signal, and data in the burst signal is read based on the burst signal detection time before communication. And a burst signal detection time point when an electric field strength detection value by the electric field strength detection means is equal to or more than a first predetermined value. First to do
A mobile wireless device comprising: a determination unit. 2. A cycle detecting means for detecting a period from the start of the electric field strength detecting operation of the electric field strength detecting means to the lapse of the predetermined cycle, and the cycle detecting means detects the lapse of the predetermined cycle. Maximum value detecting means for detecting the maximum value of the electric field strength detected value by the electric field strength detecting means in the period until the time, and the electric field strength detected value is judged to be smaller than the first predetermined value by the first judging means. When the elapse of the predetermined cycle is detected by the cycle detecting means, it is determined whether or not the maximum value detected by the maximum value detecting means is equal to or more than a second predetermined value smaller than the first predetermined value. And a second discriminating means which determines that the electric field strength detecting means detects the electric field strength of the maximum value when the second judging means judges that the maximum value is equal to or more than the second predetermined value. Processing means for processing as a burst signal detection time, and processing means, if the second judging means judges that the maximum value is smaller than the second predetermined value, that the own station exists outside the communication area of the base station. The mobile wireless device according to claim 1, further comprising: 3. The electric field strength detection means obtains an electric field strength detection value LEVEL from the actually measured electric field strength value EMF and the reference electric field strength value AVE obtained by actually measuring the received signal, and LEVEL = (| EMF | / AVE) ² . The mobile radio device according to claim 1, wherein the mobile radio device is calculated from an equation. 4. The electric field strength detection means has a memory in which the reference electric field strength value is stored in advance, and is updated by an average value of the sequentially calculated electric field strength values. Mobile radio device. 5. The electric field strength detecting means detects the 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 apparatus according to claim 1, wherein: 6. The mobile radio apparatus according to claim 1, wherein the electric field strength detection means starts an electric field strength detection operation in response to power-on of the apparatus. 7. When the burst signal detection time is detected, a unique word is detected from the burst signal, and a third judging means is provided for judging whether or not it matches the unique word of the own station. The mobile radio device according to claim 1. 8. The mobile radio apparatus according to claim 1, wherein the burst signal detection time point is newly detected when the unique word match is not judged by the third judgment means within a predetermined time. .