JPH0984109A - Two-channel simultaneous communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-channel simultaneous communication method in which a transmission/reception shared equipment is not required in a mobile machine concerning the two-channel simultaneous communication method used in a public job digital mobil communication system, for example. SOLUTION: A mobile station is constituted in such a way that a signal in which a latest guard time is replaced to a post amble within a signal format is transmitted without time alignment control in a first channel, a head burst responsiveness guard time is abbreviated in the second channel, the signal from a next pre-amble to the guard time is successively transmitted after the first channel signal and the reception end timing of the second channel in the base station coincides with a reference reception end timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-channel simultaneous communication method used in a digital mobile communication system for public works, for example.

FIG. 9 is a diagram showing a basic configuration example of a digital mobile communication system for public service, and FIG. 10 is an example of a configuration diagram of a main part of a base station of the digital mobile communication system for public service. In FIG. 9, the line control device is connected to a general public line (PSTN) or a digital public line (PSDN) via a switchboard (PBX), and is also connected to a wireless device and a control device via a transmission line to connect to the public. It monitors and controls the operating status of all commercial digital mobile communication systems.

One base station is provided within a service area (base zone) of, for example, 20 to 30 km, and transmits and receives information to and from a mobile device in its own zone via a wireless line. It has a structure as shown in 10.

That is, the base station control device in FIG. 10 monitors the operating state of its own station using a monitoring device, allocates frequencies to the transmitting device and the receiving device, and switches to a standby device when a failure occurs, and transmits / receives frequencies. Is in the 400 MHz band, for example.

A fire fighting system is one of such digital mobile communication systems for public works (for example, four-multiplexed TDMA system). The fire fighting system may transmit data such as an electrocardiogram and a pulse while the sick person reports the condition of the sick person to the doctor while the sick person is transported to the hospital by an ambulance.

In such a case, two of slot 1 and slot 2
Simultaneous voice and non-voice communication is performed by a two-channel simultaneous communication method in which one communication channel is assigned to one communication, but as described later, time alignment control is performed to absorb the propagation delay time between the base station and the mobile station. .

However, due to this control, the mobile station becomes large in size because the mobile station overlaps the reception time of slot 2 and the transmission time of slot 1 and requires a duplexer. Therefore,
It is necessary to provide a two-channel simultaneous communication method that does not require a transmitter / receiver for a mobile device.

[0008]

2. Description of the Related Art FIG. 11 is an explanatory diagram of π / 4 shift QPSK system channel (slot) arrangements for a public service digital mobile communication system, and FIG. 12 is a π / 4 shift QPSK system communication for a public service digital mobile communication system. FIG. 13 is a diagram showing a signal format of a physical channel for use in transmission, and FIG. 13 is an explanatory diagram of a transmission / reception state of a conventional example
(When normal time alignment control is performed).

FIG. 14 is an explanatory view of the function of the time alignment control system, FIG. 15 is an explanatory view of the conventional time alignment control system (in the case of one channel communication with a 4-slot configuration), and FIG. 16 is a time alignment control system. FIG. 17 is an example of a main part configuration diagram of a mobile station of a conventional example of a public service digital mobile communication system.

First, as shown in FIG. 11, the arrangement of channels (slots) of the π / 4 shift QPSK system in the digital mobile communication system for public works is as follows. ) Is inserted four,
The TDMA multiplex number is 4.

Since the transmission / reception offset and the frame offset are both 20 ms (see FIGS. 11 (a) and 11 (b)), the mobile station that receives the downlink CH1 signal from the base station changes from the reception timing. The uplink CH1 signal is transmitted to the base station with a delay of 20 ms of the transmission / reception offset (
(See Figure 11 (c)).

The signal format in the up / down direction is as shown in FIGS. 12 (a) and 12 (b). The symbols in the figure are as follows. R: Guard time for burst transient response, P: Preamble, TCH: Traffic channel, FACCH: High-speed ACCH,
SW: Sync word, CC: Color code (interference prevention code)
, SACCH: Low speed ACCH, RCH: Housekeeping bit, G: Guard time, B / I: Busy / idle bit. The numbers are the number of bits.

Here, the transmission / reception timings when the distance between the mobile station and the base station is short and there is almost no propagation delay time in space substantially match those in FIG. However, as shown in Fig. 13, the propagation delay time becomes longer as the distance becomes longer, and as shown in Fig. 13, the reception timing of slot 1 of the mobile station is only t ₀ than the transmission timing of slot 1 of the base station. Be delayed.

As shown in FIG. 11 (c), the mobile station transmits the uplink signal of slot 1 toward the base station after the transmission / reception offset time (20 ms) from the reception timing, so that the reception timing of the base station is the same as that of the downlink. Then, the signal is received with a delay of t ₀ from the transmission timing of the mobile station.

As a result, the base station causes a round trip delay of 2t ₀ (see in FIG. 13). Such a propagation delay time does not cause a problem if only one mobile station is transmitting, but if other slots in the same area are also communicating, this propagation delay time becomes a problem.

Therefore, the base station has
Time alignment control is performed so that the transmission timing of the mobile station is shorter than the 20 ms transmission / reception offset time so that the timing coincides with the reception timing when all the time axes are normalized, that is, the reference reception timing. This control will be described below (see FIGS. 14 and 15). The mobile station receiver 31b in FIG. 14 receives the downlink signal, and the reception timing extractor 21 extracts the time slot number assigned to the own station and the absolute time of the number. By this, the absolute time of the reception timing and the transmission timing of the own station can be known. When the absolute time is extracted at, the transmission timing wait counter 22 is operated.

This counter is a transmission / reception offset value (20 ms)
When counting, the count output is sent to the transmitting unit 32b, so that the transmitting unit transmits the upstream signal to the base station. The base station receiving unit 31a receives the uplink signal and sends the reception result to the delay time measuring unit 12.Since the reference timing (20 ms) from the reference timing unit 11 is also added to this measuring unit, the reference timing And the delay time value between the received signal and the received signal are measured, and the measurement result is sent to the time alignment amount determination unit 13. Since the time alignment amount determination unit matches the end of the slot sent by the mobile station with the reference reception timing of the base station, the time alignment specified value from the input delay time value (Specified value of) is determined and transmitted from the transmission unit 32a to the mobile station. The mobile station receives this downlink signal and recognizes the time alignment value in the time alignment designation receiving section 24. The mobile station changes the count range of the transmission timing waiting counter 22 using the recognized value, and transmits the upstream signal from the transmitter 32b earlier than the transmission / reception offset. Hereinafter, measurement, designation, and timing change are repeated in the same manner as in.

Here, when one frame has four channels,
As shown in FIG. 15, the first slot control unit (1a, 2a) to the fourth slot control unit (1d, 2d) having the same configuration as the time alignment control unit of FIG. Time alignment control is performed independently for each slot.

Further, in order to specifically implement the above time alignment control, for example, as shown in FIG.
41, a program ROM 42, a RAM 43, an interface INF, and the program ROM in the time alignment control unit of the base station has the procedure shown in the above, and the program ROM in the time alignment control unit of the mobile station has the above procedure. The procedures shown in, and are stored respectively.

As a result, the received signals input via the interfaces INF ₁ and INF ₂ are utilized to enable the base station and the mobile station to receive the signals.
Each CPU operates according to the corresponding procedure. Next, in the slot configuration as shown in FIG. 11, when two communication channels are assigned to one communication and simultaneous voice / non-voice communication and high-speed non-voice communication are performed, the above time alignment control is performed. As shown on the right side of 13, a mobile station requires a duplexer because the reception time of slot 2 and the transmission time of slot 1 overlap.

The overlap of slots 2 and 1 in the mobile station will be described in the study below. That is, as described above, when the base station in FIG. 13 transmits slots 1 and 2 at the reference transmission timing, the mobile station delays by the propagation delay time t _{0 in} space and slots 1 and 2 are transmitted.
After receiving, the slot 1 and 2 are transmitted to the base station with a delay of 20 ms for the transmission / reception offset value (part of, in Fig. 13).
.

Therefore, the base station determines the time alignment value by measuring the propagation delay time (2t ₀ ). (Of the slots 1 and 2 transmitted by the mobile station to the base station, the end of slot 2 is the base station. The time alignment value that matches the reference reception timing is determined) and transmitted to the mobile station (portion in Fig. 13).

The mobile station recognizes the received time alignment values of slots 1 and 2 and performs transmission earlier than the reference transmission timing of the mobile station by 2t ₀ . This allows
Receive slot 2 and transmit slot 1 overlap at the mobile station (Fig.
Part of 13).

As a result, as shown in FIG. 17, the duplexer 33
b was needed.

[0025]

In the case of normal one-channel communication, only slot 1 is provided and slot 2 is not provided.
As can be seen from the above, the reception time and the transmission time of slot 1 do not overlap with each other in the mobile station, and the duplexer is not necessary.

However, in the case of simultaneous two-channel communication, for example, a transmission / reception duplexer in the 400 MHz band is required, but there is a problem in that the mobile device becomes large because of the large capacity of this duplexer.

It is an object of the present invention to provide a two-channel simultaneous communication method that does not require a duplexer for a mobile device.

[0028]

FIG. 1 is a diagram for explaining the principle of the first and second aspects of the present invention, FIG. 2 is a diagram for explaining a transmission / reception state when time alignment control is not performed for both slots, and FIG. 3 is for slot 2 only. FIG. 9 is a diagram for explaining a transmission / reception state when time alignment control is performed in FIG.

According to the first aspect of the present invention, when two channels are assigned to one communication and the two channels are simultaneously transmitted from the mobile station to the base station, the mobile station sets the first channel in the signal format. Of these, the signal in which the last guard time is replaced with a postamble is transmitted without time alignment and control, the second burst transient response guard time is omitted on the second channel, and the signal from the next preamble to the guard time is omitted. The signal is transmitted following the signal of the first channel,
The reception end timing of the signal of the second channel at the base station coincides with the reference reception end timing.

In the second aspect of the present invention, the number of bits of the postamble is calculated from [(guard time + guard time for burst transient response)-(time alignment specified value specified by base station) × 2]. did.

That is, as described in detail above, when the time alignment control from the base station is followed, the reception time of the second slot and the transmission time of the first slot overlap,
A mobile device requires a duplexer (see the part in Fig. 13).

In order to solve this overlap, therefore, as shown in FIG. 2, the mobile station A does not perform the time alignment control from the base station for the transmission of the first slot (the transmission timing is not advanced) and the second slot. It is assumed that the transmission burst of the first slot is transmitted after the reception of (see the part in FIG. 2).
. As a result, the reception signal of the second slot and the transmission signal of the first slot do not overlap in time.

However, if the transmission burst of the second slot is also transmitted without complying with the time alignment control from the base station, this transmission burst is received by the base station with a delay of the propagation time, so that the slot 3 in the base station is received. It will overlap with the reception timing of.

This causes interference with the transmission signal of the other mobile station B using this slot (see the part of FIG. 2). Therefore, in order to solve the overlap in FIG. 2, transmission of the second slot is subject to time alignment control, as shown in FIG. At this time, if the transmission is accelerated according to the time alignment control value in the second slot with the normal signal format, the transmission burst of the first slot and the transmission burst of the second slot are overlapped, and the reception burst is also overlapped in the base station. (See the part of Figure 3).

According to the present invention, when the base station allocates two consecutive slots to two-channel simultaneous communication, the mobile station does not perform the time alignment control for the first slot, but for example, 20 ms.
The transmission / reception offset of the second slot is transmitted, and the second slot is transmitted in a time shorter than the transmission / reception offset according to the time alignment control amount from the base station so that the end of the second slot coincides with the reference reception timing at the base station. .

By making the transmission earlier in the second slot than the transmission / reception offset, the signal in the latter half of the transmission burst in the first slot and the first half in the transmission signal in the second slot overlap as shown in FIG. there is a possibility.

Therefore, in order to prevent this overlap (see the upstream frame format in FIG. 12 (a)), the guard time (G) of the first slot is omitted. Guard time (R) for burst transient response in the second slot
Omitting and sending from preamble (P), 1
It is assumed that the second slot is transmitted immediately after the slot. The postamble is transmitted after the first slot by the time (the number of bits) that compensates for the time required to continuously transmit the first slot and the second slot.

Here, the guard time (G) is used to prevent the transmission burst of the mobile station from interfering with the transmission bursts of other mobile stations due to the distance from the base station.
This is not necessary when transmission bursts are continuously transmitted from the same mobile station as in simultaneous channel communication.

Also, the burst transient response guard time (R)
Is also a guard time for reducing interference with adjacent channels at the time of burst start-up, and is unnecessary if the second slot of two-channel simultaneous communication is continuously transmitted to the first slot.

However, if the guard time and the burst transient response guard time are all omitted in and, it becomes 14 bits. If the mobile station transmits to the base station in this state, depending on the distance between the base station and the mobile station, The reception timing in may be earlier than the reference reception timing.

Therefore, as shown in FIG. 1, the number of bits of the postamble is changed according to the distance between the base station and the mobile station, that is, the value of the propagation delay time, and the end of the second slot transmitted by the mobile station. Is made to coincide with the end of the reference reception timing of the base station.

Therefore, even if the guard time and the burst transient response guard time are omitted and the first slot and the second slot are continuously transmitted, the overlap as described in FIG. 3 can be eliminated.

As a result, the mobile station does not need a duplexer.

[0044]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 4 is an explanatory diagram of signal formats and transmission / reception states of the first and second embodiments of the present invention, and FIG. 5 is an operation flow chart of the first and second embodiments of the present invention (base. Bureau),
FIG. 6 is an operation flow diagram (mobile station) of the first and second embodiments of the present invention, and FIG. 7 is an explanatory diagram of a time alignment control system implemented by the first and second present invention (two channels with a 4-slot configuration). FIG. 8 is an example of a configuration diagram of a main part of a mobile station according to the first and second embodiments of the present invention.

The present invention will be described below with reference to FIGS. 4 to 8. The parts described in detail above will be briefly described below.
The part of the present invention will be described in detail. Note that the same reference numerals throughout all the drawings denote the same objects.

First, as shown in FIG. 7, a common control unit 5 having a two-channel communication determination unit 51 in the base station and first to fourth units having the same configuration as the base station time alignment control unit in FIG.
Slot control units (1a to 1d) are provided in the mobile station, and first to fourth slot control units (2a to 2d) having the same configuration as the mobile station time alignment control unit in FIG. 14 are provided.

Here, it is assumed that two consecutive channels are allocated at the start of simultaneous two-channel communication. This channel is designated as slot 1 and slot 2. In each assigned channel, the mobile station exchanges a synchronization burst with the base station to synchronize the frequency and phase between transmission and reception, and then TCH in the signal format of FIG.
Information is transmitted using parts.

When the base station receives the upstream signal from the mobile station, it adds the received signal to, for example, the first slot controller 1a and the common controller 5. As described above, the first slot control unit 1a measures the propagation delay time 2t ₀ of the received signal, calculates the time alignment designation value using the measured propagation delay time, and calculates the time alignment designation value in the downlink signal format shown in FIG. Housekeeping (RCH) sends the specified time alignment value to the corresponding mobile station (see S1 to S4 in FIG. 5).

Further, the common control unit 5 controls the two channels (two slots) as one control unit without performing the time alignment control for each slot based on the determination result of the two-channel simultaneous communication from the two-channel communication determination unit 51. To do. However, in the case of one-channel communication, time alignment control is performed independently for each slot (see S5 in FIG. 5).

In the control of the two-channel simultaneous communication, since the time alignment control is not performed for the first slot, the reception timing at the base station has a spatial round-trip delay time (2t ₀ ) with respect to the reference reception timing. It appears as it is and is delayed by 2t ₀ .

For the second slot, when another mobile station uses this slot (in the case of one-channel communication), the above-mentioned timing overlap occurs due to the positional relationship of the mobile stations, causing interference. However, in the case of two-channel simultaneous communication, the same mobile station as the first slot uses the delay time and the overlap time.

Therefore, the delay is allowed as it is in the first slot, the time alignment control is performed only in the second slot, and the overlap between the first slot and the second slot is
As will be described later, it was dealt with by reducing guard bits and redundant bits.

That is, since the propagation delay time 2t ₀ is delayed in the first slot with respect to the reception of the base station, the reception is not waited at the reference reception timing (the RX portion in FIG. 11 (c)) and the propagation is not performed. Although it waits for the reception at the reception timing when the delay time is measured, the end of the second slot and the end of the reference reception timing are made to coincide (this method is shown in the mobile station below).

On the other hand, with respect to the transmission of the mobile station, the first slot is transmitted at a timing with a transmission / reception offset of 20 ms as shown in FIG. 11 (b), but the second slot is time aligned from the base station. A burst signal is transmitted at the transmission timing according to the specified value. However, as shown in Fig. 4 (b), the signal transmitted in the first slot has a variable length postamble (PST) instead of the guard time (G) (that is, without the period for stopping transmission). Transmit from the preamble (P) to the guard time (G) in the second slot (
(See S1 to S3 in FIG. 6).

In the case of one-channel communication, normal time alignment control is performed for each slot. (S4 in Fig. 6
See). Now, the number of bits of the variable length postamble (PST) is the number of bits obtained by the following formula.

Bit number of PST = 14−time alignment specified value × 2 Even with the maximum time alignment control, the time alignment control amount is 7 symbols (corresponding to 2t ₀ in FIG. 4, the spread of the base station zone is 7 symbols). This is the guard time of slot 1 (8 bits = 4 symbols)
And burst transient response guard time (6 bits = 3 symbols) can be absorbed. Even if the time alignment designation value = 7 symbols is substituted into the above equation, the postamble will not be 0 or less.

That is, the number of bits of the postamble is calculated using the time alignment designation value from the base station, a signal of the format shown in the lower right of FIG. 4 (b) is created, and the burst transient response guard time (R) From Postamble (PST)
Are transmitted in the first slot, and the preamble (P) to the guard time (G) are transmitted in the second slot following the first slot. At the base station, as shown in the upper right of Fig. 4 (a),
The end of slot 2 received matches the end of the reference receive timing.

As described above, FIG. 8 shows even the two-channel simultaneous communication without preparing a new signal format, and without providing a special reception synchronization system or signal extracting means for the two-channel communication. Even if the duplexer is not provided, the slots do not overlap as shown in FIG. This allows the device to be simple, inexpensive, and compact.

[0059]

As described in detail above, according to the present invention, it is possible to provide a two-channel simultaneous communication method that does not require a transmission / reception duplexer in a mobile device.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the first and second aspects of the present invention.

FIG. 2 is an explanatory diagram of a transmission / reception state when the time alignment control is not executed for both slots.

FIG. 3 is an explanatory diagram of a transmission / reception state when time alignment control is performed only for slot 2.

FIG. 4 is a signal format and transmission / reception state explanatory diagram of the first and second embodiments of the present invention.

FIG. 5 is an operation flow diagram (base station) of the first and second embodiments of the present invention.

FIG. 6 is an operation flow diagram (mobile station) of the first and second embodiments of the present invention.

FIG. 7 is an explanatory diagram of a time alignment control system implemented in the first and second aspects of the present invention (when two channels are simultaneously transmitted in a 4-slot configuration).

FIG. 8 is an example of a configuration diagram of a main part of a mobile station according to the first and second embodiments of the present invention.

FIG. 9 is a diagram showing a basic configuration example of a digital mobile communication system for public works.

FIG. 10 is an example of a configuration diagram of a main part of a base station of a digital mobile communication system for public works.

[Fig. 11] π of a digital mobile communication system for public works
FIG. 4 is an explanatory diagram of channel (slot) arrangement of a / 4 shift QPSK system.

[Fig. 12] π of a digital mobile communication system for public works
It is a figure which shows the signal format of the physical channel for communication of a / 4 shift QPSK system.

FIG. 13 is a diagram for explaining a transmission / reception state of a conventional example (when a normal time alignment control is performed).

FIG. 14 is a functional explanatory diagram of a time alignment control system.

FIG. 15 is an explanatory diagram of a conventional time alignment control system (in the case of 1-channel communication with a 4-slot configuration).

FIG. 16 is an example of a configuration diagram of a main part for implementing a time alignment control system.

FIG. 17 is an example of a configuration diagram of a main part of a mobile station in a conventional example of a digital mobile communication system for public works.

[Explanation of symbols]

11 Reference timing unit 12 Delay time measurement unit 13 Time alignment amount determination unit 21 Reception timing extraction unit 22 Transmission timing wait counter 23 Counter value changing unit 24 Time alignment designation reception unit 31 Reception unit 32 Transmission unit

Claims (2)

[Claims] 1. When communication is performed between a base station and a plurality of mobile stations using a plurality of time division multiplexed channels, a preamble follows a leading burst transient response guard time in the upstream direction. Then, in a digital mobile communication system that uses a signal format of a physical channel for communication having a guard time at the end, two channels are allocated to one communication, and two channels are simultaneously transmitted from the mobile station to the base station. At this time, the mobile station is
A signal in which the last guard time is replaced with a postamble is transmitted without performing time alignment and control, and the second burst transient response guard time is omitted on the second channel.
The signal from the next preamble to the guard time is transmitted following the signal of the first channel so that the reception end timing of the signal of the second channel at the base station matches the reference reception end timing. A two-channel simultaneous communication method characterized by: 2. The number of bits of the postamble is calculated from [(guard time + burst transient response guard time)-(time alignment specified value specified by the base station) × 2]. The two-channel simultaneous communication method according to claim 1.