JP2002335556A - Radio communication system and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication system for simultaneously transmitting information by using the same channels in respective cells transmitting information and improving the efficiency of the channels as a whole system and to provide the method. SOLUTION: The system is provided with a plurality of synchronized base stations 12-1 to 12-n, a mobile exchange station 13 taking charge of a plurality of cells allocated to the base stations and a common channel data base 15 connected to the mobile exchange station 13 through a wide communication network 14. The mobile exchange station 13 decides which channels are to be used as a control channel and a communication channel or they are previously decided as protocols. They are transmitted from the base stations 12-1 to 12-n to mobile terminals 16-1 to 16-m, and a rate that the common communication channel or the common control channel occupies among whole channels that the system possess is dynamically changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system and a method thereof, and more particularly, to the same data for a plurality of mobile terminals such as broadcast and multicast, for example, orthogonal frequency division multiplexing (OFDM).
TECHNICAL FIELD The present invention relates to a radio communication system and a radio communication system for performing radio transmission using a transmission scheme or the like.

[0002]

2. Description of the Related Art In a mobile radio communication system, a control method for performing communication using a channel in a radio section includes: a method in which each radio terminal automatically determines a communication channel; a method in which a control station performs centralized control. , Are divided into

A cellular radio communication system in which a base station controls a channel, such as a current mobile phone network, is the latter. In addition, a wireless LA in which a control station that performs channel assignment exists.
N also applies to the latter. In a wireless communication system having such a control station, the control channel and the communication channel are determined by the control station or are determined in advance.

[0004] Here, the term "channel" is a general term for means for distinguishing itself from other communications, such as a frequency band, a time zone, and a spreading code to be used. This is an expression of what specifies a communication path used for communication.

On the other hand, in a radio communication system in which a base station or a control station exists, a service area is divided into units called cells. Usually, one base station is assigned to one cell. At this time, in order to reduce radio wave interference in a cell, a communication channel used in a certain cell is not used in a peripheral cell.

First, a method of using channels in a conventional mobile communication system will be described with reference to FIG. In FIG. 28, each hexagon indicated by reference numeral 1 indicates one cell, the base station (or control station) indicated by reference numeral 2 and a radio tower in the center of each cell 1 is indicated by reference numeral 3, and Indicates a mobile terminal station (wireless terminal) in which a terminal indicated by an arrow from the base station 2 is communicating with the base station. In FIG. 28, the number (for example, CH1) attached to the arrow indicates a channel used for communication.

As shown in FIG. 28, in a conventional mobile communication system, each base station 2 performs communication using different channels (time and frequency) even if the contents to be transmitted are the same. In other words, in the conventional mobile communication system, even when information that many mobile terminal stations 3 request in common is distributed from the base station 2, each cell 1 uses different channels. I will send it. This is because, when a nearby base station 2 transmits using the same channel, a time-delayed signal arrives at the receiving terminal station, which causes intersymbol interference, thereby deteriorating the reception quality.

[0008]

However, as described above, transmitting the same data using different channels is inefficient in view of the overall channel use efficiency. As described above, in the conventional mobile communication system, there is a disadvantage that the channel is inefficiently used when transmitting information that can be commonly transmitted across cells.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to perform the same transmission in each cell transmitting information when transmitting information that can be transmitted in common across cells. It is an object of the present invention to provide a wireless communication system and a method thereof that can simultaneously transmit using a channel and thereby improve the use efficiency of the channel as a whole system.

[0010]

To achieve the above object, a wireless communication system according to the present invention comprises a plurality of communication terminals,
Each communication service area is specified, and a plurality of communication stations synchronized with each other, which communicate with a communication terminal in the service area using a signal according to the instruction with a signal according to the frequency division multiplexing transmission method, Control means capable of instructing simultaneous transmission of the same data by simultaneously using a common channel at least partially including common information as a channel to be used by the communication station.

Further, in the system of the present invention, the control means dynamically changes the ratio occupied by the common channel including the common information among all the channels owned by the system according to a predetermined condition.

In the system of the present invention, the control means pre-defines common channel information to be used by the plurality of communication stations, and allocates a common channel according to the specified information.

[0013] In the system of the present invention, the control means determines the assignment of the common channel to be used in accordance with the use situation, and causes the determined common channel information to be shared by a plurality of communication stations.

[0014] In the system of the present invention, the control means needs to use a channel in which predetermined common channel information to be used by the plurality of communication stations is specified in advance and a common channel to be used is specified. Sometimes,
Assigning a specified common channel, when there is no need to use a specified common channel to be used, the assignment of a common channel to be used is determined according to the use situation, and the determined common channel information is Share between multiple communication stations.

[0015] In the system of the present invention, the control means determines that, even if the data is to be allocated to a common channel to be transmitted, it can be transmitted earlier using the normal communication channel based on the traffic. Is assigned a normal communication channel.

Further, the system of the present invention further comprises a database for managing information on the common channel, and the control means acquires the information on the common channel by accessing the database and registers the information in the database. To update the information of the common channel.

In the system of the present invention, the communication terminal is a mobile communication terminal, and the control means performs communication before and after the handover when the communication terminal hands over from one communication station to another communication station. A common channel is set for both communication stations in order to transmit the same information from both stations.

In the system of the present invention, synchronization between communication stations is maintained by GPS.

Further, according to the present invention, a communication service area is specified, and a plurality of communication stations synchronized with each other are used.
A wireless communication method for communicating with a communication terminal in the service area using a signal according to a frequency division multiplexing transmission method using a channel according to an instruction, wherein at least a part of the channel to be used by the plurality of communication stations is used. Transmit the same data simultaneously using a common channel including common information.

Further, in the method of the present invention, of all the channels owned by the system, the ratio occupied by the common channel including the common information is dynamically changed according to a predetermined condition.

In the method of the present invention, common channel information to be used by the plurality of communication stations is defined in advance, and a common channel is allocated according to the defined information.

Further, in the method of the present invention, the assignment of the common channel to be used is determined according to the use situation, and the determined common channel information is shared between a plurality of communication stations.

In the method of the present invention, predetermined common channel information to be used by the plurality of communication stations is defined in advance, and when it is necessary to use a channel in which a common channel to be used is specified, When it is not necessary to use a channel for which a common channel to be used is specified, a common channel to be used is determined according to a use situation, and the determined common channel information is assigned to a plurality of channels. Shared between communication stations.

Further, according to the method of the present invention, even if the data to be allocated to the common channel to be transmitted is determined to be able to be transmitted earlier by using the normal communication channel based on the traffic, the normal transmission is performed. Assign a communication channel.

Further, in the method of the present invention, the information of the common channel is obtained by accessing a database for managing the information on the common channel, and the information of the common channel is updated by registering the information in the database.

In the method of the present invention, when the communication terminal performs a handover from one communication station to another communication station, the communication terminal communicates with both communication stations before and after the handover in order to transmit the same information from both communication stations. Set a common channel for this.

Further, in the method of the present invention, synchronization between communication stations is maintained by using GPS.

According to the present invention, for example, when data to be transmitted to the communication terminal is obtained by the control means, the data to be transmitted is data to use a common channel such as broadcast or multicast. Is determined. As a result, if the data is normal data that does not use the common channel, channel allocation is performed using the processing of a normal base station. When the data uses the common channel, it is determined whether or not the data to be transmitted has a predefined common channel to be transmitted, such as a control channel. If a common channel is defined, it is transmitted from the communication station using that channel. Otherwise, it is necessary to determine the common channel to use. In this case, for example, it is checked whether or not the same transmission data has already been transmitted in a nearby cell, and if so, the communication station is instructed to perform transmission using the channel used for that. Is done. As a result, the communication station receiving the instruction transmits the data using the channel corresponding to the instruction. Otherwise, it is necessary to determine the common channel to use. At this time, for example, it is first determined whether to transmit using a normal channel instead of setting a common channel. That is, even if the data to be transmitted is multicast or broadcast data that should use the common channel, the communication channel is set when the number of terminals requesting the data is small and the traffic volume in the cell is small. In other words, there is a case where transmission can be performed earlier by using the data. If a communication channel is used, normal channel allocation processing (performed on the communication channel) is performed. Otherwise, the common channel to be used is determined, and this is notified to the communication station in charge of the neighboring cell. Alternatively, when a database for managing the common channel exists on the network, the common channel can be notified by registering in the database.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 shows a first embodiment of a network of a communication system according to the present invention.
FIG. 2 and FIG. 3 are system configuration diagrams for explaining a channel use mode of the communication system according to the present invention. The first embodiment is an example in which the system of the present invention is applied to a mobile communication system.

The mobile communication system 10 includes a plurality of cells 11-1 to 11-n indicated by hexagons in the figure, and a base station (or control station) 12 as a plurality of communication stations arranged for each cell. -1 to 12-n, a mobile switching center (router) 13 as control means, a wide area communication network 14 such as a WAN or the Internet, a common channel database 15, and a plurality of mobile terminals 16-1 to 16-m. It has as. 2 and 3 show a system configuration in the case of seven cells (n = 7), and base stations 12-1 to 12-7 are located at the center of each of cells 11-1 to 11-7. Is shown as a radio tower. In the present embodiment, the control means according to the present invention is a mobile switching center (router) 13.
However, the present invention is not limited to this example, and various modes such as arranging at a specific control station or arranging a specific base station are possible.

In the mobile communication system 10, the base stations are configured to transmit synchronously using, for example, GPS. As a modulation method, for example, O
The FDM system is adopted. Then, in the mobile communication system 10, it is determined whether the data to be transmitted is data that should use a common channel, such as broadcast or multicast. As a result, if the data is normal data that does not use the common channel, As shown in FIG. 2, channels (communication channels, 7 channels CH1 to CH7 in FIG. 2) are processed using normal base station processing.
Is assigned. Also, it is determined whether the data to be transmitted is data that should use a common channel, such as broadcast or multicast. As a result, if the contents to be transmitted using the common channel are the same, as shown in FIG. , Each base station can simultaneously transmit using the same channel. Although the example of FIG. 3 shows an example in which the channels of all the cells are set to the same channel CH1, as will be described later, the ratio occupied by the common channel among all the channels owned by the system is a predetermined ratio. Dynamically change according to conditions. The same applies to packet transmission services. This is because the packet switching is regarded as a circuit switching in which the transmission time is very short and the connection is set up every time.

As described above, in the present mobile communication system 10, the same data can be transmitted simultaneously from a plurality of base stations that are geographically close to each other by using the OFDM system as the modulation and demodulation system. Thereby, as shown in FIG. 3, when transmitting the same information, the same channel can be used in all cells, and the channel can be used efficiently. Here, OFDM will be described.

OFDM uses a plurality of carriers to transmit signals. By riding on multiple carriers,
The transmission rate of a signal per carrier is reduced (to-for the carrier). If the signal transmitted using the n-th carrier at time t is d _n (t), the carrier f
The signal S on _n is as follows.

[0034]

(Equation 1)

Therefore, OF signal which is a composite wave of these signals
The DM signal S (t) is as follows.

[0036]

(Equation 2)

Here, N is the total number of carriers.

When such OFDM modulation is performed, the transmission rate of a signal per carrier is reduced, so that a delayed wave caused by a delay due to reflection or propagation in a radio section can be easily contained within one symbol of the signal. This makes it possible to create a state in which intersymbol interference is unlikely to occur,
Equalizers are easy or unnecessary on the receiver side.
That is, the resistance to the delayed wave is enhanced.

When transmitting an OFDM signal, as will be described in detail later, a time for absorbing a delay in a radio section called a guard interval (guard period) is usually provided. Is inserted into. This further reduces interference between symbols of the transmission signal.

By using such an OFDM transmission system, a system configuration in which the same contents are simultaneously transmitted from a plurality of synchronized stations becomes possible. This is called SFN (single
frequency network). This is applied to a wireless communication system that is centrally managed by a synchronized base station or control station, such as a cellular mobile phone or a wireless LAN, and is used as a control channel or a common channel used for broadcast, multicast, etc. Channel can be used more efficiently.

In this embodiment, when allocating channels, a plurality of neighboring base stations are set as one group, and a common communication channel and control channel are set within the group. In these common channels, data having the same content is transmitted using the same frequency and the same time zone.

The ratio of data communication in wireless communication is rapidly increasing. Further, most of the data communication is downloading information from a wired communication network to a wireless terminal, and depending on the information, broadcasting or multicasting is performed and transmitted to a plurality of terminals in a cell. In such a case, it is more efficient to transmit by setting a common channel.

As a system for setting a common channel and performing high-speed download, an OFDM communication system employing a high-speed downlink system as shown in FIGS. 4 and 5, for example, can be configured. it can. In such an OFDM communication system, a user communicates a relatively low bit rate signal such as a control signal through an existing mobile phone network, and downloads a high bit rate signal such as digital data to be downloaded (a high bit rate is required). Traffic channel) is configured to transmit at high speed on the added downlink. less than,
An OFDM communication system employing a high-speed downlink system, and a channel configuration and allocation method will be described in the order of association with the drawings.

FIG. 4 is a diagram showing an outline of an OFDM communication system employing a high-speed downlink system.
FIG. 1 is a diagram illustrating a specific configuration example of an OFDM communication system employing a high-speed downlink system.

In FIG. 4, M1 is a mobile terminal station as a communication device, B1 is a normal base station, B2 is a high-speed downlink base station, N1 is an existing portable telephone network (existing cellular wired network), N2 Indicates a data communication network such as the Internet, and N3 indicates a data communication network for a high-speed downlink system. 4 and 5, the high-speed downlink system is referred to as “W-OF
DM ”.

In the OFDM communication system 100, as shown in FIG. 4, the mobile terminal station M1 controls packet retransmission due to a data error (ARQ: Automatic Request fo).
r Repetition) are transmitted from the existing base station B1,
The data is transmitted via a network (cellular phone network) N1.
The transmission capacity of the high-speed downlink system is much larger than the transmission capacity of the existing mobile phone system, and a large amount of digital contents such as images and moving images downloaded by the mobile terminal station M1 is: A traffic channel requiring a high bit rate is transmitted at high speed in a short time via this high-speed downlink system. All information is exchanged via IP. The data communication network N3 for the high-speed downlink system is also connected to a data communication network N2 such as the Internet. The high-speed downlink data communication network N3 is connected to the network N1.
Various control signals at a relatively low bit rate are transmitted from the base station B1 of the mobile phone to the high-speed downlink system data communication network N3 via the network N1. Further, a control signal for retransmission control (ARQ) of a packet due to a data error from the mobile terminal station M1 is transmitted to the data communication network for the high-speed downlink system via the existing base station B1 and the network (cellular phone network) N1. It is transmitted to the control center at N3. In this case, the digital content requested by the mobile terminal station M1 from the control center is retransmitted to the mobile terminal station M1 via the data communication network N3 for the high-speed downlink system and the base station B2.

The OFDM communication system 100A shown in FIG.
Are mobile terminal stations (MS) M1 to M3,
Base stations (BS) B1 to B4, existing cellular wired network N1, Internet
, A data communication network N3 having a database for additional downlink, and a mobile routing center (MRC) CTR for additional downlink network as main components. ing. This control center CTR corresponds to, for example, a mobile switching center (router) 13 as control means in FIG.

The base station B1 has an existing cellular function, the base station B2 has an additional downlink function, the base station B3 has an existing cellular function, and the base station B4 has an additional downlink function. have. The wired network N1 is connected to the base stations B1 and B3 by, for example, wired communication lines L1 and L2. Control center C
TR is connected to base stations B2 and B4 by communication lines L3 and L4. The control center CTR is connected to the network N1 by a communication line L5,
6 is connected to the data communication network N2, and the communication line L7 is connected to the data communication network N3.

The OFDM communication systems 100 and 10
At 0A, the cell can be configured, for example, as shown in FIG. In FIG. 6, the solid line indicates a range (cell) in which each of the existing mobile phone base stations can communicate with the mobile terminal. What is indicated by a broken line is a range in which each base station of a broadband wireless (W-OFDM) communication system additionally provided exclusively for downlink (communication from the base station to the mobile terminal station) can communicate with the mobile terminal station ( Cell).

Specifically, as shown in FIG. 6 (A), a method of installing and configuring the same cell shape in the same manner as a base station of an existing portable telephone system, and as shown in FIG. 6 (B), How to install base stations only in areas where there are many users,
As shown in FIG. 6 (C), a base station having a smaller output than an existing mobile phone base station is installed in an area where many users exist,
As shown in FIG. 6 (D), a method of configuring a cell (micro cell) smaller than a cell of a mobile phone, installing a base station having a higher output than an existing cell phone base station, As shown in FIG.
6 (B) and 6 (C) (the overlay cell system), or FIG.
As shown in (F), there is a method of forming micro cells along a main road.

In this embodiment, a cell is formed by, for example, the method of FIG. 6A, that is, a method of installing and configuring the same cell shape as a base station of an existing portable telephone system.

[0052] W- adopting a high-speed downlink system
In the OFDM communication system 100A, for example, each of the base stations B1 to B4 has a GPS (Global Positioning System).
m) Receiving the signal is perfectly synchronized. The OFDM signal transmitted from the base station in the W-OFDM communication system 100A is transmitted using a frame described later as one unit, and all the base stations are configured to transmit the frame at the same timing.

The W-OFDM communication system 100A
, A frequency band different from the frequency band of the existing mobile phone system is allocated. The frequency band allocated to the W-OFDM communication system 100A is divided into a plurality of radio channels, co-channel interference is minimized, and each base station is used so that radio channels can be used effectively. Assigned in the form shown. In the example shown in FIG.
It is divided into two radio channels and assigned to each base station (cell). In FIG. 7, the numbers 1 to 12 in the regular hexagon indicate the wireless channel numbers, respectively.

Here, the OFDM communication system 10 shown in FIG.
A communication example of 0A will be described. The download request issued from the mobile terminal station corresponds to the existing mobile phone base stations B1 and B3,
The data is transmitted to a control center CTR in a high-speed downlink system network via a network N1 formed of a mobile telephone network. The control center CTR makes this download request to the data communication network N2 such as the Internet via a router. Digital data content transmitted from the data communication network N2 is transmitted to the control center C.
It is delivered from the router of the TR to the mobile terminal station via the network network of the high-speed downlink system and the base stations B2 and B4. A control signal for retransmission control due to a data error or the like is also transmitted to the control center CTR in the high-speed downlink system network via the existing mobile phone base station and mobile phone network. Control center C
The TR retransmits the digital data contents requested by the mobile terminal station to the mobile terminal station via the base station and the network of the high-speed downlink system.

Specifically, for example, the mobile terminal station M1
Transmits a signal (001) to the base station B1 in accordance with the format of the existing system in order to transmit a data download request to the control center CTR. This request signal is
Via the existing cellular network N1, the control center C
Delivered to TR. Control center C that knows the data request
The TR obtains the data (121) from the data communication network N2 via the communication line L6, and transmits the obtained data (121) to the base station B2 as data (111) via the communication line L3 in order to deliver the obtained data (121) to the mobile terminal station M1. I do. The base station B2 receiving this data (111) transmits the data (101) to the mobile terminal station M1 according to the format of the additional downlink. Thereby, the mobile terminal station M1
Can receive the requested data (101).

Alternatively, the mobile terminal station M3 transmits a signal (003) to the base station B3 in accordance with the format of the existing system in order to transmit a data download request to the control center CTR. This request signal is delivered to the control center CTR via the existing cellular network N1. The control center CTR that has received the data request obtains the data (123) from the data communication network N3 dedicated to the additional downlink via the communication line L7, and obtains the obtained data (1
23) is transmitted to the mobile terminal station M3 via the communication line L4 as data (113) to the base station B4 dedicated to the additional downlink. The base station B4 receiving this data (113) transmits the data (103) to the mobile terminal station M3 according to the format of the additional downlink. Thereby, the mobile terminal station M3 transmits the requested data (1
03) can be received.

Such an OFDM communication system 100A
In FIG. 8, the OFDM signal transmitted from the transmitting device provided in the base station to each of the mobile terminal stations M1 to M3 is composed of one frame FRM by seven time slot periods TSLT and one frame guard period TFGD, as shown in FIG. Be composed. In FIG. 8, TFRM is a frame period, T
SLT indicates a time slot period, and TFGD indicates a frame guard period. The frame guard FGD is a no signal, and is added to the end of the seven time slot strings of the frame FRM in the present embodiment. Each of the base stations B1 to B3 transmits a frame at the same timing in units of a frame constituted by seven time slots SLT and one frame guard FGD. In the present embodiment, an example is shown in which the frame guard period TFGD is added to the end of the frame. However, the frame guard period TFGD may be provided at the beginning of the frame, or may be provided at the end and at the beginning of the frame.

Each time slot SLT forming the frame FRM is formed by adding a guard GD to an effective symbol period TSBL. The time slot SLT to which the guard GD is added is a signal for the beginning or end of the effective symbol period, or a signal of a fixed period having the beginning and end, as shown in FIGS. In the example of FIG. 9, the effective symbol period TSB
The same signal as the signal at the end of L is connected to the beginning of the effective symbol period. In the example of FIG. 10, the same signal as the signal at the beginning of the effective symbol period TSBL is connected to the end of the effective symbol period. In the example of FIG. The same signal as the signal at the beginning and the end of the symbol period is connected to the end and the beginning of the effective symbol period. The time slot shown in FIG. 8 is configured by the method shown in FIG.

As described above, the effective symbol period TSBL
A frame is constructed by applying a frame guard period TFGD to a time slot sequence with a guard period TGD added to
The transmitting device for transmitting the FDM signal is mounted on the base station, and the mobile terminal stations M1 to M3 that receive the PFDM signal transmitted from the transmitting device more accurately synchronize the OFDM signal with the frame guard period added thereto. Equipped with a receiving device capable of performing such operations.

The base station transmits a prescribed pilot signal on a specific subcarrier of the channel specified by the control signal from the control center CTR, and transmits traffic from the control center, used channel information, and channel allocation information. To the mobile terminal station.

Next, examples of channel types and channel allocation rays in a W-OFDM communication system will be described.

In a W-OFDM communication system, a cell search channel (Cell Search Chan) is used.
nel) CSC, single frequency network common channel (Single Frequency Network)
rk Common Channel SFNCC, and fixed frequency reuse common channel (Fix Fre
quency Reuse Common Channel
e) The control channel of FFRCC and the traffic channel (Traffic Channel) TC are used.

The cell search channel CSC is mainly used for measuring the received electric field strength at the mobile terminal station and for allocating the optimum base station to the mobile terminal station at the control center CTR based on the measurement result.

The single frequency network common channel SFNCC is used for transmitting control information common to all mobile terminals such as channel allocation information, and also for transmitting broadcast service information such as traffic information, weather forecast, and news. . In the single frequency network common channel SFNCC, the same signal is transmitted simultaneously from all base stations or from a plurality of base stations dynamically set according to predetermined conditions. In general, since the OFDM transmission method has a strong characteristic against interference of a delayed signal, even if the same signal is transmitted from all base stations at the same time, reception at a mobile terminal station is possible.

Fixed frequency reuse common channel FFRC
C is used for transmission of time slot information when the mobile terminal station receives the traffic channel TR, that is, information such as which channel of which channel should be received among the channels allocated to the base station. Can be

FIG. 12 is a diagram showing an example of channel allocation in a high-speed downlink system. FIG.
Is assumed that the frequency bandwidth of one wireless channel is 400 kHz, and this is 7 wireless channels, 400 [kHz] × 7 =
4 shows an example of channel allocation of a high-speed downlink system having a frequency band of 2.8 [MHz].

In FIG. 12, the frequency is shown on the vertical axis and the time is shown on the horizontal axis. Each cell shown in FIG. 12 has a frequency bandwidth of 400 kHz (one radio channel) and a length of 2 m.
s indicates a frame. The cell with the upward-sloping hatching is the cell search channel CSC, the cell with the downward-sloping hatching is the single frequency network common channel SFNCC, and the cell with the upward-sloping hatching and numbered is the fixed frequency reuse common channel F.
FRCC, and simply numbered cells indicate traffic channels TC, respectively. Note that the numbers described in the cells are base station (cell) numbers, and this example shows a case where the number of repeated cells is 12. The cells with no numbers are used for transmission of control information common to all mobile terminal stations, such as channel allocation information, in the single frequency network common channel SFNCC as described above. In this channel, the same signal is transmitted simultaneously from all base stations or from a plurality of base stations dynamically set according to predetermined conditions.

In the example of FIG. 12, the cell search channel CS
C, single frequency network common channel SFNC
C, three types of control channels, fixed frequency reuse common channel FFRCC, are transmitted every 100 frames (200 ms).
4 frames (8 ms) each time. Actually, since all seven radio channels are used for transmission, 4
[Frame] × 7 [Wireless channel] = 28 [Channel]
The control signal is sent using minutes. The remaining 96 [frames] × 7 [wireless channels] = 672 [channels] are traffic channels. Hereinafter, a channel due to a difference in radio frequency is referred to as a “radio channel”, and a radio channel frame (each of the cells in FIG. 12) determined by the radio channel and the frame is referred to as a “channel”. I do.

Next, an example of the structure of a channel will be described.

As described above, the bandwidth of the radio channel is 400 kHz and the length of one frame is 2 ms. FIG.
As shown in FIG. 3, one radio channel is composed of 100 subcarriers SC, and the subcarrier interval is 4 kHz. In the example of FIG. 12, the number of subcarriers in the entire system is 100 [subcarriers] × 7 [radio channels] = 7
00 [subcarrier]. Further, as shown in FIG. 13, out of the 100 subcarriers constituting the radio channel, the subcarriers located at both ends on the frequency axis are guard subcarriers GSC1 and GSC2. These guard subcarriers GSC1 and GSC2 have no signal.

As shown in FIG. 14, one frame is composed of seven time slots having a length of 279.3 μs (2288 points) and a non-signal frame guard period TFGD having a length of 44.92 μs (368 points). It is configured. One time slot has an effective symbol period of 250 μs (2048 points) (subcarrier interval 4 kHz).
(reciprocal of z) TSBL and a guard period TGD of 29.3 μs (240 points).

In the example of FIG. 12, one cell search channel CSC is transmitted every 100 frames (200 ms, 700 channels). The reason for transmitting only one cell search channel CSC in this way is as follows.

That is, as is apparent from FIG.
When the number of control channels such as the cell search channel CSC, the single frequency network common channel SFNCC, and the fixed frequency reuse common channel FFRCC is reduced as much as possible, more traffic channels can be secured in TC, and the throughput per unit frequency band is improved. be able to. Since the single frequency network common channel SFNCC and the fixed frequency reuse common channel FFRCC are used for transmitting information necessary for the system configuration, these control channels cannot be eliminated. In that regard, the cell search channel CSC
Only transmits a pilot signal for measuring the received field strength from the base station. Therefore, in the example of FIG. 12 according to the present embodiment, the cell search channel CSC
Is divided into n subcarriers in the frequency axis direction, and the number of cell search channels CSC is reduced by allocating these subcarriers to each base station. An OFDM communication system capable of improving throughput is realized.

More specifically, as shown in FIG. 15, out of 100 subcarriers of the cell search channel CSC, two subcarriers at both ends on the frequency axis, a total of four subcarriers are guard subcarriers, and the remaining 96 The eight subcarriers are divided into twelve subcarriers and assigned to each base station. Each base station transmits a specified pilot signal on the subcarrier of the assigned channel.

As described above, the cell search channel CSC
, The channel is further divided into 12 in the frequency axis direction, and a frequency band is allocated to each base station by repeating 12 cells as shown in FIG. Each base station transmits a prescribed pilot signal within this frequency band, and the mobile terminal station measures the received electric field strength of this signal and transmits it to the control center CTR. Details will be described later.

Fixed frequency reuse common channel FFRC
C is the number of repeated cells (12 cells repeated in the example of FIG. 7)
, And one channel is allocated to each base station by repeating 12 cells as shown in FIG. The fixed frequency reuse common channel FFRCC is used for transmitting different information in each base station. The information to be transmitted includes information on which channel of which channel the mobile terminal station should receive (use channel information) and the like. This used channel information is transmitted, for example, by a channel extracting unit of the mobile terminal station, to the traffic channel T addressed to the own station.
It is used for extracting C and cell search channel CSC.

Each mobile terminal station M1 to M3 updates the received channel allocation information transmitted from the control center CTR via the base station. At this time, the mobile terminal station transmits a time other than the information addressed to itself (traffic channel TC, fixed frequency reuse common channel FFRC).
In C), the power of the receiving unit 11 is turned off to reduce power consumption. On the other hand, the mobile terminal station has a cell search channel CSC and a single frequency network common channel S.
The FNCC receives the signal every time, updates the channel allocation map, and measures the received field strength of the cell search channel. Thereby, even if the mobile terminal station moves, it is possible to always communicate with the base station having a strong reception electric field strength.

Mobile terminal station M1 having such a configuration
(-M3) receives all wireless channels when the power is turned on. Single frequency network common channel SFN
For example, the CC transmits the same signal from all the base stations B1 to B12 at the same time.
3) can receive this control channel wherever it is (even in the initial state where it is not known which base station to communicate with). By receiving the single frequency network common channel SFNCC, it is possible to know the channel allocation information, that is, the position information of the channels used by the base stations of base station numbers 1 to 12. If the channel allocation is known, the mobile terminal station M1 (〜M3) can know where and how many control channels exist in four frames. The mobile terminal station M1 (〜M3) receives only the control channel portion during standby, and turns off the reception power of the traffic channel TC portion to suppress unnecessary power consumption.

Next, mobile terminal station M1 (-M3) detects which base station to communicate with, that is, which base station has a strong electric field strength of the transmission signal. As shown in FIG. 12, each base station transmits a prescribed pilot signal on a subcarrier allocated to each base station. The mobile terminal stations M1 to M3 receive the cell search channel CSC, measure the signal strength, and select a base station having the strongest received electric field strength. The selected rally is notified to the control center CTR through a line such as an existing mobile phone and registered.

The mobile terminal stations M1 to M3 also receive the cell search channel CSC during standby,
Switching (handover) of the communication base station due to movement of the mobile terminal station is always performed (accurately, every 200 ms).
The mobile terminal station M1 (〜M3) transmits the cell search channel CS
In addition to C, common channel S for single frequency network
FNCC, fixed frequency reuse common channel FFRCC
Is always received (accurately every 200 ms). The single frequency network common channel SFNCC transmits the above-mentioned channel allocation information and also uses this channel for transmitting broadcast service information such as traffic information, weather forecast, news, and the like. Time slot information when the mobile terminal station M1 (〜M3) receives the traffic channel TC, that is,
Information such as which time slot of which channel should be received among the channels allocated to the base station is transmitted by the fixed frequency reuse common channel FFRCC. As described above, the mobile terminal station M1
(-M3) always (accurately every 200 ms) receives the fixed frequency reuse common channel FFRCC, and if there is information addressed to the own station, from this fixed frequency reuse common channel FFRCC, from which time slot of which channel , Whether the information is included or not, and receives a traffic channel TC including information addressed to the own station. A traffic channel that does not include information addressed to its own station is not received to reduce power consumption.

The control center CTR divides the cell search channel CSC by n subcarriers in the frequency axis direction,
This subcarrier is allocated to each base station, and the reception field strength measurement result from the mobile terminal station that has received the cell search channel CSC transmitted by each base station at the same time is determined. If there is a traffic (packet) to be transmitted to a certain mobile terminal station, the traffic (packet) is transmitted from the position registration information to a base station capable of communicating with the mobile terminal station. Forward.

The channels assigned to each base station are determined by the traffic volume of each base station. That is, many channels are allocated in the base station having a large traffic volume, and the number of channels allocated to the base station having a small traffic volume is reduced accordingly. The traffic volume of each base station is sequentially controlled by the control center CTR.
, And the control center CTR creates a channel allocation map based on this information. The created channel allocation map is notified to each base station, and each base station communicates with the mobile terminal station according to the channel allocation map. Each base station transmits this channel allocation map to the mobile terminal station using the single frequency network common channel SFNCC.

In the OFDM communication system employing the high-speed downlink system described above, the channel allocation has been described using the example shown in FIG.
The present invention is not limited to this, and it is also possible to allocate channels in various modes. For example, the number of radio channels and the number of repetitive cells may be the same, and each base station may be configured to cascade and use fixed frequency channels for fixed frequency reuse common channels and traffic channels.

In the above description, the cell search channel CSC is transmitted every 100 frames (200 ms, 700
Although the case where one channel is transmitted per channel or 1200 channels has been described as an example, for example, as shown in FIG. 16, it is also possible to assign a cell search channel to each base station. In this case, although the throughput per unit frequency band is inferior to the above-described embodiment, an OFDM having a synchronized base station
In a cellular radio communication system or the like that employs a modulation scheme, the effect that data can be simultaneously transmitted from a plurality of base stations can be obtained. This allows you to distribute the same information to many devices across cells,
Data can be transmitted simultaneously using the same channel in each cell transmitting information, and the channel can be used efficiently as a whole system. Further, since a channel allocated to each base station, for example, a common control channel can be determined based on the traffic volume of each base station, specific data is transmitted to a specific area, that is, a communication area obtained by a combination of base stations. It can be transmitted efficiently.

As a method for enabling transmission from a plurality of base stations, OFD is used as a modulation / demodulation method as described above.
In addition to the method using M, it is also possible to use a spread spectrum modulation method. However, in order to perform spread spectrum modulation, a device that operates with a clock higher than the band required for communication is required, and when demodulating and using a spread code, the device becomes more complicated. Therefore, in the case of high-speed data transmission, it is desirable to adopt the OFDM method. In current mobile communications, OF
Although there is no scheme for transmitting data from a plurality of base stations simultaneously using the same channel using DM, this scheme becomes more desirable as the proportion of data transmission in the entire communication increases.

As described above, the present mobile communication system 1
In 0, the control channels used in the system that are common regardless of the base station are transmitted using the same channel (time band and frequency band) in all base stations. Also, when there are data transmissions for broadcasting and multicasting to terminals in a plurality of cells, and when the total number of the terminals is a sufficiently large value, the same channel is transmitted from all base stations of the cells that need to perform data transmission. (Time band, frequency band).

As shown in FIG. 1, each of the cells 11-1 to 11-1
-N base stations 12-1 to 12-n are mobile switching centers (or routers and gateways in the case of a network that transmits packets by the TCP / IP protocol)
3 is connected. The mobile switching center 13 is connected to a wide area network 14 such as a WAN or the Internet. In the present embodiment, in a general configuration, in the block corresponding to the mobile switching center 13 (the control center CTR in the configuration of FIG. 6), which channel is used as a control channel or a communication channel is determined.
-1 to 12-n to mobile terminals 16-1 to 16-1 as wireless terminals
16-m. Therefore, which channel to use as the common channel is determined in advance as a protocol or is determined by the mobile switching center 13 as described later. And
In the present embodiment, the ratio of a common communication channel or a common control channel to all channels owned by the system is dynamically changed.

In the case where a common channel used in a certain cell is determined and is not specified, information on a common channel used in a peripheral cell must be obtained. In such a case, in the mobile communication system 10, as shown in FIG. 1, a database 15 for managing common channels is provided on the network 14, and the database 15
, The information of the common channel is acquired, and the information of the common channel is updated by registering the information in the database 15. In addition, it is also possible to constitute so that mobile switching centers may exchange information.

Next, a process for determining a common channel in the mobile communication system 10 will be described with reference to the drawings.

FIG. 17 is a flowchart showing an example of an algorithm for determining a common channel in a mobile switching center, a router, a gateway, a control station, a base station and the like employed in the mobile communication system according to the present invention. .

For example, the mobile terminal 16-n which is a wireless terminal
And when data to be transmitted to the mobile terminal 16-n is obtained (ST1), first, whether or not the data to be transmitted is data to use a common channel such as broadcast or multicast Is determined (ST2). If it is determined in step ST2 that the data is normal data that does not use a common channel, channel allocation is performed as shown in FIG. 2 using the processing of the normal base station 12-n (ST3). On the other hand, step ST
In 2, when it is determined that the data uses the common channel, it is determined whether or not the data to be transmitted is defined in advance as a common channel to be transmitted, such as a control channel (ST 4).

If it is determined in step ST4 that a common channel is defined, transmission is performed using that channel (ST5). On the other hand, if it is determined in step ST4 that the common channel is not specified, it is necessary to determine the common channel to be used.

In this case, first, it is checked whether or not the same transmission data has already been transmitted in a neighboring cell (such as a case where an advertisement is delivered or a paid data delivery service of a registration system is performed) (ST6). If it is determined in step ST6 that the same transmission data has already been transmitted in a neighboring cell, transmission is performed using the channel used for that (ST7). If it is determined in step ST6 that the same transmission data has not yet been transmitted in the neighboring cells, it is necessary to determine a common channel to be used. At this time, first, it is determined whether or not to transmit using a normal channel instead of setting a common channel (ST8).

That is, even if the data to be transmitted is multicast or broadcast data that should originally use the common channel, if the number of terminals requesting the data is small and the traffic volume in the cell is small, In other words, there is a case where transmission can be performed faster using a communication channel. Therefore, if it is determined in step ST8 that the communication channel is to be used, a normal (performed for the communication channel)
A channel assignment process is performed (ST9). On the other hand, if it is determined in step ST8 that the communication channel is not used, a common channel to be used is determined, and this is notified to the mobile switching center 13 in charge of a nearby cell (ST10).
Alternatively, as shown in FIG. 1, when a database 15 for managing a common channel exists on the network, the common channel is notified by registering in the database 15. If a management database exists, it is possible to determine the common channel in the database. Then, the base station connected to the mobile switching center 13 transmits using common (ST11).

As described above, the allocation of the common channel to be used is determined according to the use status, as shown in FIGS.

FIG. 18 shows an example in which a common channel is allocated to cells 11-1 to 11-6. In this case, FIG.
As shown in FIG. 8, a common channel CH1 is allocated to the base stations 12-1 to 12-6, and the base station 12-7
Is maintained in a state where channel CH7 is allocated as usual. Then, in the case of FIG. 18, the base station 12-1
Are the mobile terminal station 16-1 in the cell 11-1 and the mobile terminal station 1 on the boundary between the cell 11-2 and the cell 11-4.
6-2, and communicates from the base station 12-1 to the mobile terminal station 16-.
1 and the mobile terminal station 16-2.
1 transmits data. Similarly, the base station 12-1
Communicates with the mobile terminal station 16-2 at the boundary between the cell 11-2 and the cell 11-4, and data is transmitted from the base station 12-2 to the mobile terminal station 16-2 via the common channel CH1. . The base station 12-3 communicates with the mobile terminal station 16-3 in the cell 11-3 and the mobile terminal station 16-4 on the boundary between the cell 11-4 and the cell 11-6.
-3 to mobile terminal station 16-3 and mobile terminal station 16-4
Is transmitted over the common channel CH1. The base station 12-4 communicates with the mobile terminal station 16-2 on the boundary between the cell 11-2 and the cell 11-4 and the mobile terminal station 16-4 on the boundary between the cell 11-4 and the cell 11-6. Then, data is transmitted from base station 12-4 to mobile terminal station 16-2 and mobile terminal station 16-4 via common channel CH1. The base station 12-5 includes a mobile terminal station 16-5, a cell 11-2, and a cell 11-4 in the cell 11-5.
Mobile station 16-2 and cell 11-4 at the boundary with
Communicates with the mobile terminal station 16-4 at the boundary between the mobile station 16-4 and the cell 11-6, and is common to the mobile terminal station 16-5, the mobile terminal station 16-2, and the mobile terminal station 16-4 from the base station 12-5. Data is transmitted by the channel CH1. Base station 12-
6 communicates with the mobile terminal station 16-6 in the cell 11-6 and the mobile terminal station 16-4 at the boundary between the cell 11-4 and the cell 11-6. Station 1
Data is transmitted to 6-6 and the mobile terminal station 16-4 by the common channel CH1. Also, the base station 12
-7 communicates with the mobile terminal station 16-7 in the cell 11-7, and data is transmitted from the base station 12-7 to the mobile terminal station 16-7 through the normally allocated channel CH7.

FIG. 19 shows cells 11-1 to 11-5.
Is a case where the common channel is assigned to the. In this case, as shown in FIG. 19, a common channel CH1 is allocated to base stations 12-1 to 12-5, and base station 12-6 is allocated.
And the base station 12-7 is maintained in a state where the channels CH6 and CH7 are allocated as usual. And
In the case of FIG. 19, the base station 12-1 is connected to the mobile terminal station 16-1 and the cell 11-2 in the cell 11-1 and the cell 1
The mobile station communicates with the mobile terminal station 16-2 at the boundary with the terminal 1-4, and data is transmitted from the base station 12-1 to the mobile terminal station 16-1 and the mobile terminal station 16-2 via the common channel CH1. Similarly, the base station 12-1 communicates with the mobile terminal station 16-2 at the boundary between the cell 11-2 and the cell 11-4, and is shared by the base station 12-2 and the mobile terminal station 16-2. Data is transmitted by the channel CH1. Base station 1
2-3 communicates with the mobile terminal station 16-3 in the cell 11-3 and the mobile terminal station 16-4 on the boundary between the cell 11-4 and the cell 11-6, and moves from the base station 12-3. Data is transmitted to the terminal station 16-3 and the mobile terminal station 16-4 via the common channel CH1. Base station 12-4
Communicates with the mobile terminal station 16-2 at the boundary between the cell 11-2 and the cell 11-4 and the mobile terminal station 16-4 at the boundary between the cell 11-4 and the cell 11-6. -4
Transmits data to the mobile terminal station 16-2 and the mobile terminal station 16-4 via the common channel CH1. The base station 12-5 is connected to the mobile terminal station 16 located in the cell 11-5.
-5, communicating with the mobile terminal station 16-2 at the boundary between the cell 11-2 and the cell 11-4 and the mobile terminal station 16-4 at the boundary between the cell 11-4 and the cell 11-6, and 12-
5 to the mobile terminal station 16-5, the mobile terminal station 16-2, and the mobile terminal station 16-4, data is transmitted by the common channel CH1. Then, the base station 12-6 communicates with the mobile terminal station 16-6 in the cell 11-6, and transmits data via the channel CH6 normally allocated from the base station 12-6 to the mobile terminal station 16-6. Is sent. Further, the base station 12-7 communicates with the mobile terminal station 16-7 in the cell 11-7, and the base station 12-7 transmits the mobile terminal station 16-7.
Data is transmitted by the channel CH7 normally allocated to -7.

As described above, according to the first embodiment, a plurality of synchronized base stations 12-1 to 12-n,
A mobile switching center 13 in charge of a plurality of cells allocated to these base stations and a mobile switching center 1 via a wide area network 14.
The mobile switching center 13 determines which channel is to be used as a control channel or a communication channel, or determines it in advance as a protocol. 1 to 12-n to the mobile terminals 16-1 to 16-
m, and among all the channels owned by the system,
Since the ratio occupied by the common communication channel or the common control channel is dynamically changed, in a cellular radio communication system having a synchronized base station or a wireless LAN having a synchronized transmission station, Can transmit data from the same base station at the same time. As a result, when distributing the same information to many terminals across cells, it becomes possible to simultaneously transmit data using the same channel in each cell transmitting the information. Can be used efficiently. In addition, by dynamically changing the ratio occupied by the common control channel, in other words, by dynamically changing the combination of base stations for setting the common channel, communication obtained in a specific area, that is, a combination of base stations is achieved. There is an advantage that specific data can be efficiently transmitted to the service area.

Further, according to the present embodiment, the control center C
A plurality of base stations for transmitting a prescribed pilot signal on a specific subcarrier of the channel indicated by the TR and transmitting traffic from the control center, used channel information, and channel allocation information to the mobile terminal station; Dividing every n subcarriers in the frequency axis direction, allocating the subcarriers to each base station, and judging the reception field strength measurement result from the mobile terminal station that has received the cell search channel transmitted simultaneously by each base station In the case where there is a traffic (packet) to be transmitted to a certain mobile terminal station, the mobile terminal station registers the location of the mobile terminal station with which mobile station can communicate with the mobile terminal station. Control center CTR for transferring traffic (packets) to a base station capable of communicating with the control center CTR
And updates and retains the channel allocation information AI transmitted from the base station via the base station, and extracts a cell search channel based on the retained channel allocation information,
The mobile terminal stations M1 to M3 that measure the reception electric field strength of each of the subcarriers divided into n in the frequency axis direction of the extracted channel and transmit the determination result to the control center are provided, so that the following effects can be obtained. it can.

That is, since the cell search channel is divided into n subcarriers in the frequency axis direction and this subcarrier is allocated to each base station, the number of cell search channels can be reduced, and more traffic channels can be used. As a result, the throughput per unit frequency band can be improved. Also, by reducing the number of cell search channels, channel allocation information can be reduced, and the number of common channels in a single frequency network can be reduced. Therefore, according to the present embodiment, it is possible to reduce the number of control channels that must be received when the mobile terminal station is in the standby state. As a result, there is an advantage that power consumption can be suppressed low and the terminal can be reduced in size and weight.

Second Embodiment FIG. 20 is a configuration diagram showing a second embodiment of the network of the mobile communication system according to the present invention, and FIG. 21 uses an overlay according to the second embodiment of the present invention. It is a figure showing the example of system composition of a cellular network.

The second embodiment differs from the first embodiment in that the mobile communication system 10A uses a large cell (macro cell) covering a wide area as a cell.
Is that there is a mobile communication system 101A using small cells (micro cells) 111 and 112 covering a smaller area in one cell 11A. Such a system configuration is called cell overlay.

In this mobile communication system 10A,
Base station 12-1 of macro cell 11A, micro cell 11
The base stations 12-2 and 12-3 are synchronized with each other by using a GPS, a synchronization protocol using a wired network, or the like. In the mobile communication system 10A, the base stations 12-1, 12-2, and 12-3 of the macro cell 11A and the micro cells 111 and 112 together form part of the same communication network. And these base stations 12-
1, 12-2 and 12-3 are connected to the same mobile switching center 13.

Such a system configuration is, for example, a boundary between a region where the communication capacity is to be locally increased and a general region,
To perform high-speed data transmission, the microcell 111,
112 is locally adopted and the macro cell 11
This is applied to a place where a service corresponding to high-speed movement is provided using A. Even in such a case, the terminal 16 is able to connect the macro cell 11A and the micro cell 11A.
1 (or 112) of both base stations 12-1, 12-2
(Or 12-3), the information of the common channel transmitted simultaneously can be received.

According to the second embodiment, the above-described first embodiment
The same effect as that of the embodiment can be obtained.

Third Embodiment FIG. 22 is a configuration diagram showing a third embodiment of the network of the mobile communication system according to the present invention.

The difference between the third embodiment and the second embodiment is that the base station 12-1 of the macro cell 11A
And the base stations 12-2,1 of the microcells 111,112.
2-3 form a part of a different communication network. The base station 12-1 of the macro cell 11A and the micro cell 11
1, 112 base stations 12-2, 12-3 are connected to different mobile switching centers 13-1, 13-2, respectively.

In FIG. 22, mobile switching center 13
-1 and 13-2 are connected via wide area communication networks 14-1 and 14-2. Other configurations are the same as those of the first and second embodiments.

According to the third embodiment, the first
The same effect as that of the embodiment can be obtained.

Fourth Embodiment FIG. 23 is a diagram for explaining a mobile communication system according to a fourth embodiment of the present invention.

In the fourth embodiment, a configuration in the case where a common channel is used for handover of a wireless terminal will be described. Here, handover refers to changing the communication destination from the base station 12B-1 of the cell 11B-1 currently communicating with the base station 12B-2 of the adjacent cell 11B-1. At this time, if a common communication channel can be used as a communication channel for handover, mobile terminal 16 can receive data transmitted from both base stations 12B-1 and 12B-2, and a momentary interruption (momentary interruption) occurs. Handover without communication channel disappears).

Although such a handover is used as a soft handover in CDMA communication using direct spread spectrum modulation, it can be similarly performed using OFDM.

According to the fourth embodiment, the above-described first embodiment
In addition to obtaining the same effect as the effect of the embodiment, regarding data transmitted from a plurality of base stations using a common channel, if data is within the area of the base station, the data can be received without instantaneous interruption during handover. There are advantages that can be.

Fifth Embodiment FIG. 24 is a block diagram showing a fifth embodiment of the network of the communication system according to the present invention, which is used in a wireless LAN having a control station having a function of centrally controlling a communication channel. FIG. 1 is a diagram illustrating an example of a network configuration when a system is applied. FIG. 25 is a diagram illustrating an example of a system configuration when the present system is applied to a wireless LAN having a control station having a function of centrally controlling a communication channel according to the fifth embodiment.

The fifth embodiment differs from the first embodiment in that a communication system according to the present invention for a wireless LAN is applied. As a result, instead of the base station, the control stations 17-1, 17-2,.
7-n, and each of the control stations 17-1, 17-2,.
17-n are connected to, for example, a wired network, and connected to other control stations to configure the LAN 18. LAN18
Has a configuration similar to that of the mobile switching center of FIG. 1, and is connected to a common channel database 15 via a wide area communication network 14. In such a case, if the control stations are appropriately synchronized with each other, they need not necessarily be connected by a wired network. Any system may be used as long as the control stations are connected in synchronization.

As shown in FIG. 25, a plurality of control stations 17-1, 17-2,...
It is apparent that the transmission from the control station to the terminal can be simultaneously performed using the same channel. Note that the example in FIG. 25 is an example in which there are three control stations.

That is, in the fifth embodiment,
For example, in a specific control station, which channel is used as a control channel or a communication channel is determined or a protocol is determined in advance, which is transmitted to a terminal, and among all channels owned by the system, a common It is configured to dynamically change the ratio occupied by a communication channel or a common control channel.

According to the fifth embodiment, the above-described first embodiment
The same effect as that of the embodiment can be obtained.

Sixth Embodiment FIG. 26 is a block diagram showing a communication system according to a sixth embodiment of the present invention.
FIG. 3 is a diagram illustrating a network configuration example when the present communication system is applied to an N hybrid system.
FIG. 27 is a diagram illustrating a configuration example of an overlay system in a hybrid system of a cellular mobile communication network and a wireless LAN according to the sixth embodiment.

Communication system 10 according to the sixth embodiment
20D, the cellular mobile communication network has a configuration equivalent to the cellular communication system 10A using the overlay according to the second embodiment of FIGS.
In the AN, for example, a control station 17D-1 is connected to a plurality of LANs 18-1 and 18-2, and the control station 17D-1 is connected to the wide area network 14 via one LAN 18-1.

In the communication system 10D, the base station 121 of the macro cell 11A, the base station 122 of the micro cell 111, and the control station 17D-1 of the LAN are synchronized with each other. In this case as well, FIG.
, Each base station 121, 122, the control station 17D
Obviously, data transmission can be performed from -1 to the same terminal 16 using the common channel.

In the communication system 10D, the wireless LA
N is connected to WAN 18-1. It is connected to a wide area communication network 14 such as internet, and is connected to the mobile switching center 13 of the cellular mobile communication network 10A via this. Information on the common channel is defined in advance or otherwise managed between the wireless LAN control station 17D-1 and the mobile switching center 13 of the cellular mobile communication network. Also in the sixth embodiment, when a database 15 for managing the common channel exists on the network, the common channel is notified by registering in the database 15.

According to the sixth embodiment, the first
The same effect as that of the embodiment can be obtained.

[0124]

As described above, according to the present invention,
In a cellular wireless communication system having a synchronized base station or a wireless LAN having a synchronized transmitting station, it is possible to simultaneously transmit data from a plurality of base stations. Thereby, when distributing the same information to many terminals spanning between cells, it becomes possible to transmit data simultaneously using the same channel in each cell transmitting information, and as a whole system,
Channels can be used efficiently.

Also, by dynamically changing the ratio occupied by the common control channel, in other words, by dynamically changing the combination of base stations for setting the common channel, it is possible to change the ratio depending on the specific area, that is, the combination of base stations. There is an advantage that specific data can be efficiently transmitted to the obtained communication area.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a network of a mobile communication system according to the present invention.

FIG. 2 is a system configuration diagram for explaining a channel use mode of the mobile communication system according to the present invention.

FIG. 3 is a system configuration diagram for explaining a channel use mode of the mobile communication system according to the present invention.

FIG. 4 OFDM employing a high-speed downlink system
FIG. 1 is a diagram illustrating an outline of a communication system.

FIG. 5 OFDM employing a high-speed downlink system
FIG. 2 is a diagram illustrating a specific configuration example of a communication system.

FIG. 6 is a diagram for explaining a cell configuration method in the communication system of FIG. 4;

FIG. 7 is a diagram showing an example of wireless channel allocation according to the embodiment.

FIG. 8 is a diagram illustrating a configuration example of an OFDM signal including a frame guard according to the present invention.

FIG. 9 is a diagram illustrating a method of forming a time slot including a guard of an OFDM signal according to the present invention.

FIG. 10 is a diagram illustrating a method of forming a time slot including a guard of an OFDM signal according to the present invention.

FIG. 11 is a diagram illustrating a method of forming a time slot including a guard of an OFDM signal according to the present invention.

FIG. 12 is a diagram illustrating an example of channel allocation of a high-speed downlink system, where the frequency bandwidth of one wireless channel is 400 kHz, and this is seven wireless channels, 400 [kHz] × 7 = 2.8 [MHz]. FIG. 3 is a diagram illustrating an example of channel allocation of a high-speed downlink system having the frequency band of FIG.

FIG. 13 is a diagram illustrating a configuration example of a channel.

FIG. 14 is a diagram illustrating a specific configuration example of a frame according to the present invention.

FIG. 15 is a diagram illustrating a configuration example of a cell search channel according to the present invention.

FIG. 16 is a diagram illustrating another example of the channel allocation of the high-speed downlink system.

FIG. 17 shows a mobile switching center, a router, a gateway, a control station, and a mobile switching center employed in the mobile communication system according to the present invention.
9 is a flowchart illustrating an example of an algorithm for determining a common channel in a base station or the like.

FIG. 18 is a diagram illustrating an example of dynamic assignment of a common channel according to the present invention.

FIG. 19 is a diagram illustrating an example of dynamic assignment of a common channel according to the present invention.

FIG. 20 is a configuration diagram showing a second embodiment of the network of the mobile communication system according to the present invention.

FIG. 21 is a diagram illustrating an example of a system configuration of a cellular network using an overlay according to a second embodiment of the present invention.

FIG. 22 is a configuration diagram showing a third embodiment of the network of the mobile communication system according to the present invention.

FIG. 23 is a diagram for explaining a fourth embodiment of the network of the mobile communication system according to the present invention.

FIG. 24 is a configuration diagram showing a fifth embodiment of the network of the communication system according to the present invention, in which the present system is applied to a wireless LAN having a control station having a function of centrally controlling a communication channel; It is a figure showing the example of network composition.

FIG. 25 is a diagram illustrating an example of a system configuration when the present system is applied to a wireless LAN having a control station having a function of centrally controlling a communication channel according to a fifth embodiment.

FIG. 26 is a configuration diagram showing a sixth embodiment of the communication system according to the present invention, wherein the cellular mobile communication network and the wireless L
FIG. 3 is a diagram illustrating an example of a network configuration when the present communication system is applied to a hybrid system of an AN.

FIG. 27 is a diagram illustrating a configuration example of an overlay system in a hybrid system of a cellular mobile communication network and a wireless LAN according to a sixth embodiment.

FIG. 28 is a diagram for describing a method of using channels in a conventional mobile communication system.

[Explanation of symbols]

10, 10A to 10D: communication system, 11-1 to 11
-N cell, 11A macro cell, 111 micro cell, 12-1 12-n, 121, 122 base station, 1
3 mobile switching center (or router), 14 wide area communication network, 15 common channel database 15, 16-1 to 16
16-m: mobile terminal, 171- to 17-3: control station, 1
7D-1, 18, 18-1, 18-2 ... LAN, 10
0,100A W-OFDM communication system, M1 to M3
... mobile terminal station (MS), B1 to B4 ... base station (BS),
N1: an existing cellular wired network; N2: a data communication network such as the Internet; N3: a data communication network having a database for an additional downlink; CT
R ... the control center (MRC) for the additional downlink network.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroaki Takahashi 6-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F-term (reference) 5K067 CC02 CC14 DD25 EE02 EE10 EE63 HH23 JJ11 JJ17 JJ35

Claims (29)

[Claims] A communication service area is specified with each of a plurality of communication terminals, and each of the plurality of communication terminals communicates with a communication terminal in the service area using a signal according to an instruction using a signal according to a frequency division multiplexing transmission method. Control capable of instructing simultaneous transmission of the same data by simultaneously using a plurality of synchronized communication stations and a common channel at least partially including common information as a channel to be used by the plurality of communication stations. Wireless communication system comprising: 2. The wireless communication system according to claim 1, wherein said control means dynamically changes a ratio occupied by a common channel including common information among all channels owned by the system according to a predetermined condition. 3. The wireless communication system according to claim 1, wherein said control means preliminarily defines common channel information to be used by said plurality of communication stations, and allocates a common channel according to the prescribed information. 4. The wireless communication system according to claim 2, wherein said control means preliminarily defines common channel information to be used by said plurality of communication stations, and allocates a common channel according to the prescribed information. 5. The wireless communication system according to claim 1, wherein said control means determines allocation of a common channel to be used according to a use situation, and causes the determined common channel information to be shared among a plurality of communication stations. . 6. The wireless communication system according to claim 2, wherein said control means determines allocation of a common channel to be used according to a use situation, and causes the determined common channel information to be shared among a plurality of communication stations. . 7. The control means, wherein predetermined common channel information to be used by the plurality of communication stations is defined in advance, and when it is necessary to use a channel in which a common channel to be used is defined, When it is not necessary to use a channel for which a common channel to be used is specified, a common channel to be used is determined according to a use situation, and the determined common channel information is assigned to a plurality of channels. Claim 1: Sharing between communication stations
A wireless communication system according to claim 1. 8. The control means, wherein predetermined common channel information to be used by the plurality of communication stations is specified in advance, and when it is necessary to use a channel in which the common channel to be used is specified, When it is not necessary to use a channel for which a common channel to be used is specified, a common channel to be used is determined according to a use situation, and the determined common channel information is assigned to a plurality of channels. 3. The communication station is shared between the communication stations.
A wireless communication system according to claim 1. 9. The control means, if it is determined that the data can be transmitted earlier using the normal communication channel based on the traffic even if the data is to allocate a common channel to be transmitted, The wireless communication system according to claim 1, wherein a communication channel is allocated. 10. The control means, if it is determined that the data can be transmitted earlier using the normal communication channel based on the traffic even if the data is to allocate a common channel to be transmitted, The wireless communication system according to claim 2, wherein a communication channel is allocated. 11. A database for managing information on a common channel, wherein the control means obtains information on the common channel by accessing the database, and registers the information on the common channel by registering the information in the database. 2. The wireless communication system according to claim 1, wherein said information is updated. 12. A database for managing information on a common channel, wherein the control unit acquires information on the common channel by accessing the database and registers the information on the common channel by registering the information in the database. 3. The wireless communication system according to claim 2, wherein said information is updated. 13. The communication terminal is a mobile communication terminal, and when the communication terminal performs a handover from one communication station to another communication station, the control means performs the same operation on both communication stations before and after the handover. The wireless communication system according to claim 1, wherein a common channel is set for both communication stations for transmitting information. 14. The wireless communication system according to claim 1, wherein synchronization between communication stations is maintained by GPS. 15. A communication service area is specified, and a plurality of communication stations synchronized with each other are used to transmit a signal according to a frequency division multiplexing transmission method using a communication terminal in the service area and a channel according to an instruction. A wireless communication method for communicating, wherein the same data is transmitted simultaneously using a common channel including at least a part of common information as a channel to be used by the plurality of communication stations. 16. The wireless communication method according to claim 15, wherein a ratio occupied by a common channel including common information among all channels owned by the system is dynamically changed according to a predetermined condition. 17. The wireless communication method according to claim 15, wherein common channel information to be used by the plurality of communication stations is defined in advance, and a common channel is allocated according to the defined information. 18. The wireless communication method according to claim 16, wherein common channel information to be used by said plurality of communication stations is specified in advance, and a common channel is allocated according to the specified information. 19. The wireless communication method according to claim 15, wherein allocation of a common channel to be used is determined according to a use situation, and the determined common channel information is shared among a plurality of communication stations. 20. The wireless communication method according to claim 16, wherein allocation of a common channel to be used is determined according to a use situation, and the determined common channel information is shared among a plurality of communication stations. 21. Predetermined common channel information to be used by the plurality of communication stations is specified in advance, and when it is necessary to use a channel in which a common channel to be used is specified, the specified common channel is set. Assignment, when it is not necessary to use a channel for which a common channel to be used is defined, the assignment of the common channel to be used is determined according to the use situation, and the determined common channel information is
The wireless communication method according to claim 15, wherein the wireless communication method is shared between a plurality of communication stations. 22. Predetermined common channel information to be used by the plurality of communication stations is specified in advance, and when it is necessary to use a channel in which a common channel to be used is specified, the specified common channel is used. Assignment, when it is not necessary to use a channel for which a common channel to be used is defined, the assignment of the common channel to be used is determined according to the use situation, and the determined common channel information is
17. The wireless communication method according to claim 16, wherein the wireless communication method is shared between a plurality of communication stations. 23. A request for allocating a normal communication channel when it is determined that data can be transmitted earlier using a normal communication channel based on the traffic even for data to which a common channel to be transmitted is allocated. Item 16. The wireless communication method according to Item 15. 24. Even if data to be assigned a common channel to be transmitted is determined to be able to be transmitted earlier using a normal communication channel based on the traffic, a request for allocating a normal communication channel is made. Item 17. A wireless communication method according to Item 16. 25. A method for acquiring information on a common channel by accessing a database for managing information on the common channel, and updating the information on the common channel by registering the information in the database.
The wireless communication method as described. 26. An apparatus for acquiring information on a common channel by accessing a database for managing information on the common channel, and updating the information on the common channel by registering the information in the database.
The wireless communication method as described. 27. When the communication terminal performs handover from one communication station to another communication station, a common channel is used for both communication stations in order to transmit the same information from both communication stations before and after the handover. The wireless communication method according to claim 15, wherein the setting is performed. 28. When the communication terminal performs a handover from one communication station to another communication station, a common channel is used for both communication stations in order to transmit the same information from both communication stations before and after the handover. 17. The wireless communication method according to claim 16, wherein the setting is performed. 29. The wireless communication method according to claim 15, wherein synchronization between communication stations is maintained using GPS.