JPH0823574A - Communication equipment of mobile object - Google Patents

Abstract

PURPOSE:To make common the synchronizing circuit of a mobile terminal to be used for both the microcell system of a TDMA/TDD system and the macrocell system of a CDMA/TDD system by making common the basic frame constitution of a transmission channel for the respective systems. CONSTITUTION:The TDMA/TDD system is provided with the same frame constitution as a PHP system, and the CDMA/TDD system makes the basic frame constitution (frame time) for transmission/reception common with the TDMA and multiplexes respective N channels. Then, one part of a frequency band or a modulation/demodulation system to be used for both the systems of the TDMA/TDD system and the CDMA/TDD system and further the amount of information data (the number of bits) to be transmitted for one frame per channel of both the systems are made common. Thus, one part of a radio part, modulating/demodulating part (a second-order modulation circuit 110 and a first-order demodulation circuit 113) and base band transmission/reception data processing part at the mobile terminal (such as the encoding/decoding processing part for voice, for example), is made common.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication device such as a digital cellular telephone which secures a communication line for a wide range of mobile objects by using radio.

[0002]

2. Description of the Related Art The multiple access system is a line connection system in which a plurality of stations simultaneously communicate in the same band, and there are several systems. TDMA (Time Divisio
n Multiple Access) is a time division multiple access
This is a method in which a radio frequency is time-divided, a specific time zone is assigned to a user, and communication is performed in the assigned time zone. In addition, CDMA (Code Division Multiple Acces
s) is code division multiple access, and is a technique for performing multiple access by spread spectrum communication in which the spectrum of an information signal is spread and transmitted in a band sufficiently wider than the original information bandwidth. The direct spread system is a system in which a spread sequence code is directly multiplied by an information signal in spread.
TDD (Time Division Duplex) is a transmission / reception same-band system, also called a ping-pong system, and is a system for performing communication by time-dividing the same radio frequency into transmission / reception. As an advantage of TDD system, paper "Micro-picocellular communication and network configuration" (Nakajima: 6th session)
Circuits and Systems Karuizawa Workshop (April 19-2
0, 1993) pp.121-126), the transmission diversity can be applied to the base station, which is advantageous in that the mobile station does not need space diversity and can be downsized. ing.

Among these, the TDMA / TDD system in which TDMA and TDD are combined is a PHP (Personal H) which is the next generation digital cordless telephone system in Japan.
andyPhone) system as well as DECT under development in Europe
Used in the system. For example, PHP has a frame structure as shown in FIG.
With 5ms, 5ms of transmission and reception combined as 1 frame,
4 channels are multiplexed.

On the other hand, the CDMA system has a higher frequency utilization efficiency than the TDMA in the cellular system and can accommodate a larger number of users. In the direct sequence CDMA system, when the desired transmitter is far from the receiver and the undesired transmitter is near, the received power of the interfering station becomes larger than that of the desired station. The processing gain (spreading gain) alone cannot suppress the cross-correlation between spreading codes, and there is a problem of "far-and-far problem" that communication with a desired station becomes impossible. For this reason, in the cellular system, transmission power control (power control) according to the state of each transmission line is indispensable in the line (uplink) from the mobile terminal to the base station side.

The CDMA / TDD system is described in the paper "POWER CO
NTROL IN PACKETS SWITCHED TIME DIVISION DUPLEX DIR
ECT SEQUENCE SPREAD SPECTRUM COMMUNICATIONS "(R.ESM
AILZADEH, M.NAKAGAWA, A.KAJIWARA, proc. Of VTC'92,
(pp.989-992, 1992), it is possible to know the state of the transmission line in the transmission frequency band from the received signal by transmitting and receiving signals multiplexed by direct spreading in the same frequency band. It is known that the power control of the transmission signal effective for the near-far problem, which is a problem of the direct sequence CDMA, can be performed relatively easily. Also, T
Since it is the DD system, the transmission diversity can be applied to the base station, so that the size of the mobile device can be reduced.
FIG. 7 shows an example of the frame structure. In this figure, channels 1 to N are N multiplexed. However, in this system, since time division is used for transmission and reception, in cellular communication, it is necessary to synchronize transmission and reception timing not only between the mobile terminal and the base station but also between the base stations. In addition, a guard time (GT) is provided in order to avoid collision of transmission / reception signals due to deviation of transmission / reception timing.

On the other hand, around 2000, with the aim of constructing a future public land mobile communication system (FPLMTS) of a world unified system, the multiple access system of this system is being studied mainly by ITU. The CDMA system has a higher frequency utilization efficiency than the TDMA in the cellular system and can accommodate a larger number of users. Therefore, the radius of the wireless zone has a larger macro zone than that of the TDMA type micro cell system. The above FPLMT
It is attracting attention as a strong candidate for the S multiple access method. Already as the FPLMTS frequency band, 1885 to 2025MHz
And 2110-2200MHz have been decided to be used, but P is the next generation digital cordless telephone system.
The radio frequency band used for the HP system and the DECT system is the 1.9 G band, which matches a part of the FPLMTS frequency band. Therefore, considering the application of the CDMA / TDD system as the multiple access system of FPLMTS, the development of a mobile terminal capable of communicating with both the FPLMTS and the next-generation digital cordless telephone system using a part of the frequency band has been developed. It is expected that it will be necessary, and it is desirable that the system be as common as possible from the viewpoint of downsizing and cost reduction.

FIG. 8 shows a conventional example of a mobile terminal which can be used in both the TDMA / TDD system and the CDMA / TDD system in the coexisting state, and FIG.
(A) shows the case where both systems are arrange | positioned in the state which adjoins, (b) shows the case where it arranges in the state which a cover area overlaps. Also, TDMA system and CDM
The frame length of the A system is different as shown in FIG.

In FIG. 8, the TDMA system and the CDM are shown.
When the information data transmission speeds of the A system are different, and the circuit configuration on the transmission side is in the TDMA mode, for example, the transmission data 801 which has undergone the voice encoding processing in the voice data transmission is frame synchronized by the frame assembling circuit 802. (UW) signal and associated control signal are added to form a frame, which is digitally modulated (differential coding, PSK modulation, filtering, etc.) by the primary modulation circuit 803 and up-converted by the secondary modulation circuit 804. After being placed on the carrier, the transmission power control circuit 8 is switched through the changeover switch 805.
After adjusting the power at 06, it is transmitted through the switch 807.

Also in the CDMA mode, similarly, the transmission data 808, which has been subjected to the encoding processing and the like in another circuit, is added with a frame synchronizing signal for the CDMA system, an accompanying control signal, etc. in the frame assembling circuit 809 to form a frame. Is 1
After being digitally modulated by the next modulation circuit 810, code-spread by the spreading circuit 811, up-converted by the secondary modulation circuit 812, the power is adjusted by the transmission power control circuit 806 via the changeover switch 805, and then the switch Sent through 807.

On the receiving side, in the TDMA mode, the received signal is down-converted and detected (quasi-synchronous detection, etc.) by the primary demodulation circuit 814 via the changeover switch 807 and the changeover switch 813 to become a baseband signal. Further, it is processed by the secondary demodulation circuit 815 to obtain received data 816. In addition, the UW signal is detected by the UW detection circuit 817 from the result of the secondary demodulation circuit 815, and the synchronization circuit 81
At 8 the synchronization is acquired and held.

The same applies to the case of the CDMA mode, and the received signal is down-converted and detected (quasi-synchronous detection, etc.) by the primary demodulation circuit 819 via the switch 807 and the changeover switch 813, and then by the despreading circuit 820. Correlation detection is performed, and Rake combining processing or the like is performed by the secondary demodulation circuit 821 to obtain received data 822. Further, the UW detection circuit 823 detects the UW signal from the result of the secondary demodulation circuit 821, and the synchronization circuit 824 acquires and holds the synchronization.

[0012]

However, in the above-mentioned conventional mobile communication device, since the frame lengths of both systems are different and the frame synchronization timings are relatively asynchronous, the frame synchronization is made corresponding to each of them. It is necessary to change the transmission / reception switching timing to perform communication.
Therefore, in order to realize zone switching in a state where both systems overlap or are adjacent to each other, different UWs are required because different frame synchronizations of the two systems are taken.
A detection circuit and a synchronization circuit are required, resulting in a complicated circuit configuration.

In each of TDMA and CDMA modes,
On the transmission side, up to the secondary modulation circuit has a separate circuit configuration,
Further, on the receiving side, it is necessary to have a separate circuit configuration for the primary demodulation circuit and thereafter, which causes a problem that the hardware scale becomes large.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an excellent mobile communication device having a simple circuit configuration.

[0015]

In order to achieve the above object, the present invention provides a TDMA / TDD system small zone microcell system and a CDMA / TDD system macrocell system each having a larger macrozone. A base station having the same basic frame configuration (frame time) of the transmission channel and equipped with one or both of the above-mentioned schemes can be used not only between neighboring base stations of the same scheme as its own station but also between base stations of different schemes. The mobile terminal is provided with means for establishing transmission / reception frame synchronization,
Area of the micro cell system based on the TDMA / TDD system when the mobile terminal is equipped with a device capable of communicating with both the TDMA / TDD system and the communication request / setting or when the zone is switched by the movement of the mobile terminal. If it is located inside, the line connection is first made to the base station of the microcell system by manual or automatic switching, and if there is no available free line in the microcell system or outside the area of the microcell system. When it is located, the line connection is made to the base station of the macro cell system by the CDMA / TDD system by manual or automatic switching.

Further, according to the present invention, the microcell system base station is provided with a radio channel scanner, and the use condition of the radio channel is periodically searched to find a radio channel which is not used by a neighboring microcell system. The wireless channel is assigned in response to a line connection request.

[0017]

Therefore, according to the present invention, since the transmission / reception frame lengths of both systems are the same, the frame synchronization timing can be synchronized between both systems, and the communication can be performed at the common transmission / reception switching timing.
As a result, it is not necessary to newly establish another frame synchronization even when implementing zone switching in a state where both systems overlap or are adjacent to each other, and it is not necessary to separately provide a UW detection circuit and a synchronization circuit. Simpler configuration.

Further, according to the present invention, by preferentially connecting the mobile terminal to the micro cell system, the radio frequency can be spatially repeatedly used, and the frequency utilization efficiency can be improved. Furthermore, by shortening the wireless communication portion, it is possible to provide an inexpensive line to subscribers by using a wired public telephone communication network and to reduce the transmission power of the mobile terminal, thus making the mobile station terminal smaller. Or, the continuous talk time can be extended.

[0019]

1 shows an example of the configuration of a mobile terminal of a mobile communication device according to an embodiment of the present invention. FIG. 2 shows the TD of the present invention.
An example of frame configurations of the MA / TDD system and the CDMA / TDD system is shown. In this embodiment, the TDMA / TDD system has the same frame structure as the PHP system, and the CDMA / TDD system has the same basic frame structure (frame time) for transmission / reception as the above TDMA.
Each N channel is multiplexed for 5 ms. Furthermore, a guard time (GT) of 0.2 ms is provided. P
In the HP system, 16 bits (about 42 μs) are provided as guard bits (G). Since the guard width of 0.2 ms depends on the environment (mainly the zone radius) to which the system is applied, it does not have to be fixed. Further, this guard time can also be considered as a part of the transmission bit that constitutes the frame as a guard bit (G) as in the case of PHP.

In this case, since the transmission / reception frame lengths of both systems are the same, the base station provided with the device of one system or both systems is not limited to the neighboring base stations of the same system as its own station, but also the base stations of different systems. In addition, as shown in FIG. 3, the transmission / reception frame timings can be synchronized with each other, and the mobile terminal can communicate at the transmission / reception switching timing common to both systems. As a result, even when both systems realize zone switching in an overlapping or adjacent state as shown in FIG. 9, it is not necessary to newly establish another frame synchronization, and the circuit configuration of the UW detection circuit and the synchronization circuit can be improved. It can be simplified.

In FIG. 1, 101 is transmission data and 10 is transmission data.
Reference numeral 2 denotes a transmission baseband unit, which has different circuit configurations in the TDMA mode and the CDMA mode.
103 is a selector switch for switching between both modes, 1
04 is a frame assembling circuit in the TDMA mode, 10
Reference numeral 5 is the primary modulation circuit. 106 is a frame assembling circuit in the case of CDMA mode, 107 is its primary modulation circuit,
Reference numeral 108 is a diffusion circuit. 109 is a changeover switch for changing over both modes, 110 is a secondary modulation circuit, 111
Is a transmission power control circuit, and 112 is a switcher for switching between transmission and reception. Reference numeral 113 is a primary demodulation circuit for performing primary demodulation of the received data, 114 is a changeover switch for switching between both modes, and 115 is a TDMA mode,
Secondary demodulation circuit for secondary demodulating the received signal, 11
6 is a UW detection circuit, 117 is a synchronization circuit, 118 is a CDM
In the A mode, a despreading circuit for despreading a received signal, 119 is a secondary demodulation circuit thereof, 120 is a changeover switch for switching between the two modes, 121 is received data, and 122 is a changeover switch. TDM for
This is an A / CDMA selection signal.

In the present embodiment, the frequency band used in both the TDMA / TDD system and the CDMA / TDD system, a part of the modulation / demodulation system, and further 1 of both systems.
By making the amount of information data (the number of bits) transmitted in one frame per channel common, the radio unit and the modulation / demodulation unit (secondary modulation circuit 110 and primary demodulation circuit 113 in FIG. 1) of the mobile terminal, and the base A part of the band transmission / reception data processing unit (for example, a voice code decoding processing unit) is shared.

Next, the operation of this embodiment will be described.
In the case of the TDMA mode, for example, the transmission data 101 for which the voice encoding process in the voice data transmission has been completed is added with a frame synchronization (UW) signal, an accompanying control signal, etc. in the frame assembly circuit 104 via the changeover switch 103. And is frame-structured, digitally modulated (differential coding, PSK modulation, filtering, etc.) by the primary modulation circuit 105, and the secondary modulation circuit 110 is passed through the changeover switch 109.
After being up-converted by, the carrier is up-converted, the power is adjusted by the transmission power control circuit 111, and then transmitted through the switch 112.

In the CDMA mode, the circuit configuration of the transmission baseband unit 102 is different from that of TDMA. The transmission data 101, which has been subjected to the encoding processing and the like, is frame-structured by adding a frame synchronization signal for the CDMA system, an accompanying control signal, etc. in the frame assembly circuit 106, digitally modulated in the primary modulation circuit 107, and further spread. Circuit 10
After code spreading at 8, the TD is switched through the changeover switch 109.
Like the MA mode, it is up-converted by the secondary modulation circuit 110, adjusted in power by the transmission power control circuit 111, and then transmitted through the switch 112. At this time, the secondary modulation circuit 110 and the transmission power control circuit 111 can be realized with a common circuit configuration only by changing the operation clock and the like.

On the other hand, on the receiving side, in the TDMA mode, the received signal is down-converted and detected (quasi-coherent detection, etc.) from the switch 112 by the primary demodulation circuit 113 to become a baseband signal, and is transmitted via the changeover switch 114. Further processed by the secondary demodulation circuit 115, the changeover switch 120
The received data 121 is obtained via the. The UW detection circuit 116 detects the UW signal from the result of the secondary demodulation circuit 115, and the synchronization circuit 117 acquires and holds the synchronization.

Similarly in the CDMA mode, the received signal is down-converted and detected (quasi-coherent detection, etc.) by the primary demodulation circuit 113 via the switch 112, and the despreading circuit 118 detects correlation. Further, the secondary demodulation circuit 11
9, the Rake combining process is performed, and the changeover switch 120
The received data 121 is obtained via the. The UW detection circuit 116 detects the UW signal from the result of the secondary demodulation circuit 119, and the synchronization circuit 117 acquires and holds the synchronization. Since the frame timings of both systems are synchronized, it is not necessary to newly establish another frame synchronization when switching to a different mode such as when switching zones. The circuit can be shared and simplification can be achieved.

FIG. 4 shows another embodiment of the present invention, which is a TDM
This is an example of the case where the primary modulation schemes of both the A and CDMA systems and the frame synchronization signal and the associated control signal forming the frame are common, and the transmission baseband unit of the above embodiment is made common to further simplify the circuit configuration. It has been transformed. In FIG. 4, 201 is transmission data, 202 is a transmission baseband unit, a frame assembling circuit 203, a primary modulation circuit 2
04, a changeover switch 205, and a spread circuit 206. The changeover switch 205 controls the spread circuit 206 not to be passed in the TDMA mode and the spread circuit 206 to be passed in the CDMA mode. Other components 2
07 to 220 are the same as the components 109 to 122 shown in FIG. 1, and the same operation is performed.

As described above, according to each of the above-described embodiments, the mobile terminal does not require a complicated circuit configuration, and the mobile terminal of FIG.
In the arrangement where the coverage areas of both systems are adjacent to each other, the mobile terminal can perform communication by the TDMA system at the position A and communication by the CDMA system at the position B, and move to the adjacent zone during communication. Even in this case, the communication can be continued without newly re-establishing the frame synchronization. Also in FIG. 9B, the TDMA system is at the positions A and B, and the C is at the position C.
Communication with the DMA system is possible with one mobile terminal. Further, similar to FIG. 9A, A to C, C to B
It is possible to continue the communication without newly re-synchronizing the frame even when the mobile station moves to the communication.

By the way, in each of the above embodiments, FIG.
, The mobile terminal can be connected to both the TDMA system and the CDMA system when the mobile terminal is located in the microzone TDMA system and in the macrozone CDMA system. There is a concern that communication traffic will be concentrated in a CDMA system that does not need to be switched, in which case the total subscriber capacity of both systems may decrease, resulting in a decrease in frequency utilization efficiency. Therefore, in such a case, it is a good idea to distribute the communication traffic between the micro cell system and the macro system.

FIG. 5 shows the configuration in such a case. In FIG. 5, an ellipse 301 indicates the coverage area of the base station 302 of the macro cell system based on the CDMA / TDD method. The ellipse 303 and the ellipse 304 are TD, respectively.
The coverage area of base stations 305 and 306 of the microcell system by MA / TDD system is shown. The base station 305 of the microcell system is provided with a wireless channel scanner 307 that searches the usage status of surrounding wireless channels. The base station 302 of the macro cell system is the exchange 3
08 is connected to the public telephone communication network 309, and the base stations 305 and 306 of the microcell system are connected to the control device 3
It is connected to the public telephone communication network 309 via 10.
The base stations 302, 305, and 306 are in frame synchronization with each other directly or through the exchange 308 and the control device 310. It is assumed that the macro cell system and the micro cell system are assigned different frequency bands. Further, the mobile terminal 311 can communicate with either the microcell system or the macrocell system automatically or manually.

At the time of communication request / setting (outgoing / incoming) or zone switching due to movement of the mobile terminal 311, the mobile terminal 311 covers the coverage area 30 of the microcell system.
3 and there is an unused radio channel available in the base station 305, the mobile terminal 311 and the base station 3 of the microcell system are automatically or manually operated.
Connect the line between 05. On the other hand, when there is no unused wireless channel available and the mobile terminal 311 is located outside the coverage area 303 of the micro cell system, the base station 3 is accessed by accessing the macro cell system.
Connect the line with 02.

As a result, the mobile terminal 311 is first accommodated in the microcell system, and the microcell system has a smaller radius than the macrocell system, so that frequency utilization efficiency can be improved by spatially reusing radio frequencies. Further, since the communication line of this system is short in the wireless section by being accommodated in the micro cell system, the transmission power of the mobile terminal can be smaller than that of the communication line of the macro cell system. Therefore, the power consumption can be reduced, the mobile terminal can be downsized, and the continuous talk time can be extended. Further, by first being accommodated in the microcell system, a wired public telephone communication network can be effectively used, and an inexpensive communication line can be provided to the subscriber.

Radio frequency allocation to individual microcells in the TDMA / TDD microcell system may be fixed or may be dynamically allocated by the controller 310. In addition, the base station 30
5 has a function of searching the unused radio channel by periodically searching the radio frequency utilization status in the vicinity by the radio channel scanner 307, and therefore, it is possible to drastically change the existing microcell system. Instead, the microcell system can be relocated or newly installed, and the system can be flexibly constructed.

[0034]

As is apparent from the above-described embodiment, the present invention makes it possible to use a common synchronizing circuit for a mobile terminal and modulation / demodulation in a system in which a TDMA / TDD system and a CDMA / TDD system coexist. This has the effect of making circuits common and simplifying them. Also, by preferentially connecting the mobile terminals connectable to both systems to the TDMA / TDD system microcell system, it is possible to expand the subscriber capacity of the entire system including both systems and to improve the frequency utilization efficiency. .

[Brief description of drawings]

FIG. 1 is a block diagram of a mobile terminal of a mobile communication device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of a transmission / reception frame configuration of a transmission channel in the embodiment.

FIG. 3 is a TDMA / TDD system and a CDM according to an embodiment.
Schematic diagram showing an example in which transmission / reception frame synchronization of both systems of the A / TDD system is taken

FIG. 4 is a block diagram of a mobile terminal of a mobile communication device according to another embodiment of the present invention.

FIG. 5 is a TDMA / TDD system and CDM according to an embodiment.
Schematic diagram showing the system configuration when both systems of the A / TDD system are arranged in an overlapping state

FIG. 6 is a schematic diagram showing a frame configuration of a PHP system.

FIG. 7 is a schematic diagram showing a frame structure of a CDMA / TDD system.

FIG. 8 is a block diagram showing an example of a mobile terminal of a mobile communication device in a conventional example.

FIG. 9 (a) TDMA / TDD system and CDMA / TD
Schematic diagram showing that both systems of D system are arranged adjacent to each other (b) Schematic diagram showing that both systems of TDMA / TDD system and CDMA / TDD system are arranged in an overlapping state

FIG. 10 is a schematic diagram showing an example in which the transmission / reception frame lengths of the TDMA / TDD system and the CDMA / TDD system are different.

[Explanation of symbols]

 101, 201 Transmission data 102, 202 Transmission baseband section 103, 205 Changeover switch 104, 203 Frame assembly circuit 105, 204 Primary modulation circuit 106 Frame assembly circuit 107 Primary modulation circuit 108, 206 Spreading circuit 109, 207 Changeover switch 110 , 208 Secondary modulation circuit 111, 209 Transmission power control circuit 112, 210 Switching device 113, 211 Primary demodulation circuit 114, 212 Changeover switch 115, 213 Secondary demodulation circuit 116, 214 UW detection circuit 117, 215 Synchronous circuit 118, 216 Despreading circuit 119, 217 Secondary demodulation circuit 120, 218 Changeover switch 121, 219 Received data 122, 220 TDMA / CDMA selection signal 301 CDMA / TDD system cover area 302 Macrocell system base Station 303 and 304 TDMA / TDD scheme base station 307 radio channels scanner 308 exchange 309 public telephone network 310 the controller coverage area 305 and 306 micro-cell system

Claims (2)

[Claims] 1. A TDMA / TD as a multiple access method.
D (Time Division Multiple Access / Time Division
Duplex) small zone microcell system having communication means and CDMA / TDD (Code Divisio)
n Multiple Access / Time Division Duplex) method is provided and a macro cell system of a macro zone larger than the small zone is provided, and both types have a common basic frame structure for transmission / reception of a transmission channel. ,
A base station equipped with one or both of the above systems is connected to a public telephone communication network directly or through an exchange or a control device, and is provided with means for synchronizing transmission / reception frames with peripheral base stations. , The mobile terminal is TD
The mobile terminal can communicate with both the MA / TDD system and the CDMA / TDD system, and the mobile terminal can use the TDMA / TDD system for microcells when requesting or setting a communication with a device or switching the zone by moving the mobile terminal. If it is located in the area of the system, the line is first connected to the base station of the microcell system by manual or automatic switching, and if there is no available free line in the microcell system and the above-mentioned microcell system A mobile communication device characterized in that when it is located outside the area, it is manually or automatically switched to establish a line connection to a base station of a macro cell system based on the CDMA / TDD system. 2. A micro-channel system base station is equipped with a radio channel scanner, which periodically searches the radio channel usage status to find a radio channel that is not used by a neighboring micro-cell system, and requests connection of a line. The mobile communication device according to claim 1, wherein the wireless channel is allocated according to