JPH1198550A - Base station device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the number of mobile stations which are simultaneously connected to a base station by individually receiving an access signal transmitted from a mobile station device by means of respective sectors, comparing the wave detecting outputs and selecting the sector being suitable for communication. SOLUTION: The mobile station 109 reports the ratio Rtp of outgoing traffic channel reception power as against a pilot signal reception power to a base station at regular intervals. In the meantime, when the base station 103 monitors the power ratio Rtp so as to observe that the power ratio Rtp becomes equal to below a certain threshold value, the reception power is observed concerning the other two sectors and the sector where max. reception power is obtained is searched. The base station 103 adds receiving signals concerning more than two sectors so as to execute max. ratio synthesization. The base station 103 stops link exchange about the sector with min. reception power when the power ratio Rtp reported from the mobile station 109 becomes more than a certain threshold value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to Code Division Multiple Access (hereinafter referred to as "CDM").
A ". Regarding a base station device in a communication system, for example, a personal communication system (Personal Commu)
nication Services, hereinafter "PCS". ) And a base station device in a mobile communication system such as a digital cellular system.

[0002]

2. Description of the Related Art Conventionally, the following documents exist for CDMA communication systems.

Reference 1: "Mobile Station-Base Station
Compatibility Standard for Dual-Mode Wideband Spre
ad Spectrum Cellular System, TIA / EIA / IS
−95, July 1993, USA, ”Reference 2;“ CDMA: Principles of Spread Spectrum Comm
unication, Addison Wesley, 1995. Reference 3: "NTT DoCoMo Technical Journal Vol.1"
No.2 pp.21-29 ”Here, Document 1 describes a radio interface between a mobile station and a base station in a CDMA communication system. Document 2 describes an arrangement of base stations in the CDMA communication system in Document 1. Reference 3 describes PDC (Personal Digital C) which is the current digital cellular telephone.
ellular) describes the arrangement of base stations and sectorization.

In a conventional CDMA communication system that performs transmission power control in order to reduce communication interference with other users, transmission power can be reduced by implementing soft handover and utilizing cell diversity, thereby making it possible to reduce transmission power. The aim is to increase the number of mobile stations that can be connected per station and improve system efficiency.

[0005]

[0005] However, Document 1
In the CDMA communication apparatus according to the standard scheme or the embodiment according to Document 2, an omnidirectional antenna is used as an antenna of each base station, and a signal after carrier modulation is used as a radio transmission signal via these antennas. It is configured to send out.

For this reason, in the uplink from a certain mobile station to a certain base station, transmission signals from other mobile stations interfere with each other, deteriorating communication quality, and reducing the number of connected mobile stations per base station. There was a problem of doing.

Therefore, time division multiple access (hereinafter referred to as “TDMA”) according to Reference 3
That. ) A technique for a PDC digital cellular telephone using the method, that is, a method of dividing one cell into a plurality of sectors to increase the frequency reuse efficiency and increase the number of mobile stations simultaneously connected to the base station. If it can be applied to a CDMA communication system, it is considered to contribute to solving the above-mentioned problem.
No specific system configuration or control method for application to a communication system is disclosed.

[0008]

[Means for Solving the Problems]

(A) In order to solve this problem, in the first invention, one or more mobile station devices and code division multiplex access in at least one or more sectors among at least two or more sectors in a serving cell are provided. A base station device that communicates spread-coded user data using a communication method, and includes the following means.

(1) At the time of call setup, an access signal transmitted from a mobile station device which has requested a call or responded to the call request is separately received by receiving means prepared for each sector. And a plurality of correlation detection means for performing correlation detection on each of the received signals, and (2) by comparing detection outputs of the plurality of correlation detection means, respectively.
Selection switching means for selecting a sector suitable for communication with the mobile station device.

(B) In the second invention, a code division multiple access communication system is provided with one or more mobile station devices in at least one sector among at least two sectors in the cell under the jurisdiction. And a base station apparatus for communicating spread-coded user data using the following means.

[0011] That is, (1) when a decrease in the reception state of the mobile station apparatus is detected from the reception state information notified from the mobile station apparatus in communication, a transmission signal transmitted from the mobile station apparatus is transmitted. A plurality of correlation detection means for separately receiving by the reception means prepared for each sector, and correlation detection of each received signal, and (2) a mobile station by comparing detection outputs of the plurality of correlation detection means, respectively. Select a sector suitable for communication with the device, and use both the newly selected sector and the sector already used for communication as sectors to be used for communication until a good reception state is restored thereafter. Selection switching means for selecting.

It is preferable to use, as the reception state information, information on the ratio of the traffic channel reception power to the pilot signal reception power.

(C) Further, in the third invention, one or more mobile station devices are provided in at least one or more sectors among at least two or more sectors in the serving cell.
A base station apparatus for communicating spread-coded user data using a code division multiple access communication system, comprising the following means.

That is, for the sectors in the cell under the jurisdiction, the spread modulation means for spreading and coding the user data with the same spreading code regardless of the difference between the sectors is provided.

[0015]

Embodiments of a CDMA communication system using a base station apparatus according to the present invention will be described below with reference to the drawings.

(A) Overall Configuration of CDMA Communication System FIG. 1 is a conceptual diagram showing a basic connection form of a CDMA communication system according to an embodiment.

In the case of FIG. 1, the CDMA communication system includes one mobile communication control station (Mobile) connected to the communication network 101.
Communication Control Center, hereinafter referred to as "MCC". ) 102, three base stations 103 to 105 connected to and accommodated via a wired path, and four mobile stations 106 to 109 communicating with at least one of these base stations. It is configured.

Here, the communicable range (ie, cell) 110-112 of each of the base stations 103-105 is shown surrounded by a dashed line, and its sub-cell area (ie, sector) 116-118 is shown by a long chain line. It is shown separated.

Each of the base stations 103 to 105 has a directional antenna device 113 to 113 corresponding to each sector.
115 are provided.

Next, a connection form between the respective devices will be described.

[0021] The MCC 102 and the communication network 101 are a Synchronous Digital Hierarchy.
y, hereinafter referred to as “SDH”. ) Are connected by an appropriate transmission path interface specified in (1). The transmission / exchange mode between the communication network 101 and the MCC 102 is an asynchronous transfer mode (hereinafter referred to as “A”).
TM ”. ), Even if the synchronous transfer mode (Synchr
onous Transfer Mode, hereinafter referred to as “STM”. ).

The base stations 103 to 105 and the MCC 102 are connected with an appropriate transmission line interface defined by SDH. Note that the transmission / exchange mode between the MCC 102 and each base station may be either ATM or STM, but when connected by ATM, an ATM-STM converter is provided on the downlink interface of each base station.
An upstream interface requires an STM-ATM converter.

Each mobile station 106-109 and each base station 103
The communication destination is changed between the stations to which the wireless communication path has been set, with the connection destination being changed according to the relative positional relationship. For example, in the case of FIG.
3, mobile station 107 is communicating with base station 103 and base station 104 at the same time. Also, the mobile station 108
Is not communicating with any base station. Further, the mobile station 109 is connected to the base station 103 and the two directional antenna devices 11.
4 and 115 at the same time.

Each of the mobile stations 106 to 109 communicates with a base station which can obtain the best reception condition among the reception signals received via the radio channel.

Therefore, the mobile station switches the base station for setting the radio transmission path in accordance with the movement from one cell to another cell. The communication of the mobile station with a plurality of base stations at the time of such switching is called handover. Especially,
Switching (handover) between base stations is called handover between base stations. In the case of FIG. 1, the state of the mobile station 107 corresponds to the handover between base stations. As described above, the cell diversity effect is obtained by the mobile station communicating with a plurality of base stations at the same time, the transmission power is reduced, and interference with other stations can be suppressed.

Similarly, the mobile station switches the directional antenna device for setting the radio transmission path in accordance with the movement from one sector to another sector in the same cell. The switching that occurs when the mobile station crosses a plurality of sectors in the same cell is called inter-sector handover. In the case of FIG. 1, the state of the mobile station 109 is an inter-sector handover. As described above, in the inter-sector handover, the downlink has the same cell diversity effect as the inter-base station handover, and the uplink has the inter-sector diversity, that is, the antenna diversity effect. All mobile stations have at least one or more base stations and MCC 10
2 and communicates with a mobile station belonging to the system via the MCC 102 and again via at least one or more base stations.

(B) Cell Arrangement of Each Base Station and Its Sector Arrangement FIG. 2 is a diagram showing an example of arrangement of base stations and sectors in the CDMA communication system according to the embodiment shown in FIG. Therefore, FIG. 2 shows that each of all the base stations 103 to 105 includes three directional antenna devices 113 to 115. In practice, a base station with only one omni-directional antenna device may be arranged, but the present invention does not exclude such a base station. Here, only a base station having a directional antenna device will be described. However, even when applied as a communication system in which omnidirectional antenna devices coexist, there is no problem or inconsistency in the communication system or base station arrangement.

Returning to the description of FIG. In FIG. 2, the base stations are arranged so that the cells have a regular hexagonal shape, and the directional antenna devices of any of the three sectors are arranged so that the directivity direction is directed to the boundary point of the three sectors. Sector boundaries are represented by long dashed lines. Here, as in FIG. 1, the mobile station 107 is in a communication state of inter-base-station handover between the two base stations, the base station 104 and the base station 103, and the mobile station 109 is connected to the base station 103. Communication between two sectors, the sector antenna device 114 and the sector antenna device 115, is in an inter-sector handover communication state.

(C) Configuration of Each Unit (C-1) Configuration of MCC FIG. 3 is a block diagram showing an internal configuration of the MCC 102 in the CDMA communication system according to the present embodiment. The connection relationship is the same as that in FIG. That is, MCC
102 denotes a communication network 101, a base station 103 and a base station 10.
4 is connected. However, the connection with the base station 105 is omitted.

Here, the MCC 102 includes a channel separation device 201, a channel multiplexing device 202, a protocol conversion device 203, a protocol conversion device 204, a multicast device 205, a handover memory table 206, route selection devices 207 and 208, a clock generation device 209,
It comprises a selection / synthesis device 210, a channel multiplexing device and clock inserting devices 211 and 212, a channel separating device and clock separating devices 213 and 214.

The MCC 102 constantly monitors the relative positional relationship between each mobile station and the base station, and receives reception status information (each each) between each base station or each directional antenna device notified from the mobile station. Based on the base station name (code) or antenna device name (code) and its receiving state (including information on received power, received S / N ratio and other states) and the traffic of each base station, A base station for inter-sector handover or an antenna device for inter-sector handover is determined.

Here, the function of the route selection devices 207 and 208 and the multicast device 205 to loop back the phase difference information transmitted from the base station having the current communication channel to the base station device which is to set a new communication channel. Has been realized.

Note that the multicast device 205 also functions as means for broadcasting information to a plurality of base stations involved in the handover at the time of handover between base stations, but does not use this broadcast function at the time of handover between sectors.

Similarly, the selective combining device 210 functions when selectively combining received data from a base station relating to handover between base stations based on reliability information.

The operation contents of the other parts are basically the same as the operation contents of each device in the conventional CDMA communication system, and the description is omitted.

(C-2) Configuration of Base Station FIG. 4 is a block diagram showing an internal configuration of the base station 103 in the CDMA communication system according to the embodiment. In addition,
The configuration of base stations 104 and 105 is the same as that of base station 1
Same as 03.

As shown in FIG. 4, the base station 103 includes a clock separation device and channel separation device 301, a channel multiplexing device and clock insertion device 302, a clock synchronization device 304, a frame period generation device 307, a pilot coding device 310, Spreading modulator 313, sector switching device 3
18, a channel board 321 and a sector board 322.

Here, the channel boards 321 are prepared for the number of set communication lines per base station, and include the protocol conversion devices 303 and 305, the frame configuration device and offset correction device 306, the frame decomposition device 308,
Channel encoding device 309, channel decoding device 31
1, a spread modulator 312 and a rake receiver 314.

As many sector boards 322 as the number of sectors per base station are provided, and carrier modulation device 315, carrier demodulation device 316, transmission / reception antenna device 317, carrier demodulation device 319, and reception only antenna device are provided. 320.

These two boards are characteristic parts of the present embodiment.

Here, the internal configuration of the sector switching device 318 located between the channel board 321 and the two boards and switching the connection between the boards will be described. The other device parts will be described again in the section on the operation, but the basic operation is performed by using a conventional CD.
This is the same as the device constituting the MA communication system.

First, FIG. 5 shows the internal configuration of the spread modulator 312 constituting the channel board. The spread modulator 312 according to this embodiment has a one-system two-stage configuration including a spread modulator 510 for channel identification and a spread modulator 530 for base station identification.

That is, a first stage component for performing a first process of multiplying a different first spreading code for each base station (that is, regardless of a sector as long as the sector belongs to the same base station),
A second stage component for performing a second process of multiplying a different second spreading code for each mobile station (that is, for each channel).

With this two-stage configuration, even within the same sector within the same cell, each mobile station (ie, each channel)
Different modulated signals can be transmitted. As described above, in this embodiment, even if the sector is different, the same long code is used as long as the sector belongs to the communication range (cell) of the same base station, and another long code is assigned to each sector. Code savings are possible compared to the case.

The channel identification spread modulator 510, which is the second stage component, comprises a multiplier 512 and a channel identification spread code generator 511.
A base station identifying spread modulation device 53 which is a component of the first stage
0 is the multiplier 532 and the base station identification spread modulator 53
It consists of 1.

Here, the multipliers 512 and 532 are provided with exclusive OR (eXclusive OR, hereinafter referred to as “XOR”).
A circuit is used.

Subsequently, FIG.
21 shows a configuration of a rake receiving device 314 included in FIG. The rake receiving device 314 includes the finger devices 601 and 602
And a synthesizer 603. Here, each finger device 6
01 and 602 despread the received signal with each spreading code corresponding to each spreading code assigned to each sector during inter-sector handover,
During handover between base stations, the received signal is despread with the same spreading code.

On the other hand, the sector switching device 318 has the configuration shown in FIG. The sector switching device 318 includes a selection switching device 701, a maximum value determination device 702, a matched filter 7,
03-705.

The sector switching device 318 according to this embodiment
The feature of is that matched filters 703 to 705 are prepared for each of the antennas corresponding to each sector, and the maximum value judging device 702 determines which one of the signals obtained from each matched filter 703 to 705 has the highest output. The point is that the judgment is made.

The result of this determination is used for switching the input / output path of the selection switching device 701.

In particular, at the time of a call request / call response, the selection switching device 701 converts only the demodulated signal received from the mobile station to the antenna of each sector, for which the largest output was obtained, to the base station. It operates so that it outputs to the channel board.

At the time of a call request / call response, the selection switching device 701 outputs a transmission signal to the antenna of the sector determined from the result of the above determination.

The selection switching device 701 transmits the downlink traffic channel reception power / pilot signal of reception status information (described later) included in a signal received and demodulated via the antenna of the sector currently used for communication. The value of the received power Rtp is constantly monitored, and when this value falls below a preset threshold value, in order to execute an inter-sector handover, a sector other than the sector currently used for communication is used. Is also provided to the rake receiving device 314.

In this case, the selection switching device 701
In addition to the sector currently used for communication, the same signal as the currently transmitted communication signal is output to the sector for which the highest received power is obtained.

As described above, the sector switching device 318 selects a sector to be used for communication with the mobile station and determines switching.

(C-3) Configuration of Mobile Station FIG. 8 is a block diagram showing an internal configuration of the mobile station 107 in the CDMA communication system according to the embodiment. In addition,
For mobile stations 106, 108 and 109, mobile station 10
7 has the same configuration.

As shown in FIG. 8, mobile station 107 includes antenna device 401, carrier demodulation device 402, carrier modulation device 403, rake reception device 404, and spread modulation device 4
05, channel decoding device 406, pilot extracting device 407, channel coding device 408, frame decomposing device 409, frame phase measuring device 410, frame configuration device 411, information source coding device (decoder) 412, offset calculating device 413 , Information source encoding device (encoder) 41
4. It comprises a reception state measuring device 415.

The operation contents of these units are basically the same as the operation contents of each device in the conventional CDMA communication system.

However, when executing inter-sector handover, which is an operation unique to the present embodiment, rake receiving apparatus 404 receives signals from two antenna apparatuses provided separately for every two sectors provided in the same cell. Used for the combined demodulation of the received signal. The combining operation is no different from the case of the handover between base stations.

The mobile station 107 uses the reception state measuring device 415 to determine the reception state of each reception signal (including the case where each sector belongs to a different base station or the same base station). Signal power interference ratio (hereinafter referred to as “SI
R ". ), Received power and downlink traffic channel received power / pilot signal received power Rtp) are measured, and are returned to the base station as reception state information.

Here, the signal power interference power ratio (Signal Int
erference Ratio, hereinafter referred to as “SIR”. ) And received power are information required for handover between base stations, and downlink traffic channel received power / pilot signal received power Rtp are information required for inter-sector handover.

(D) Content of Processing According to Link Direction First, the processing content of each of downlink and uplink will be described.

(D-1) Downlink Processing (D-1-1) MCC Processing First, the downlink operation in the MCC 102 will be described.

The communication network 101 outside the present system superimposes data of a plurality of connections between terminals by time multiplexing,
Send to C102. In the MCC 102, time-multiplexed data is separated into respective channels in a channel separation device 201. In the channel separation device 201 and the protocol conversion device 203, the protocol of the data link layer of the external communication network is terminated, and the protocol of the data link layer of the present system is started.

The output data of the protocol conversion device 203 is input to the multicast device 205. Communication data between terminals in the system is looped back by the route selection device 207 and input to the multicast device 205 in the same manner as the output data of the protocol conversion device 203. The multicast device 205 stores the connection for performing the handover between base stations in the handover memory table 206.
Is recognized by searching, and data multicast is performed for the corresponding connection. After this, each data is passed to the route selection device 208.

The route selection device 208 distributes the multicast data to a plurality of base stations involved in the handover between base stations. The data of the connection not related to the handover between the base stations is not multicasted in the multicast device 205 but is passed to the route selecting device 208 as it is.

At the time of inter-sector handover, similarly to the inter-base station handover, the handover is searched in the handover memory table 206 and recognized by the system. At this time, the multicast is not performed in the MCC, but is notified to the base station using the same control signal connection as the communication channel.

Channel multiplexing device and clock inserting device 2
11 and 212, data of one or more connections are inputted, multiplexed, and the base station 103, 10
4 is sent. At this time, a clock is inserted as a synchronization signal. For example, when the transmission speed is 1.544 [Mbits / s], a clock of 8 [kbits / s] is inserted.

(D-1-2) Processing of Base Station A downlink operation in the base station 103 will be described.

Clock separation device and channel separation device 3
In step 01, the multiplexed data sent from the MCC 102 is separated into respective channels, and the clock inside the base station is adjusted to the clock synchronizer 304 with reference to the separated clocks. For this, a phase-locked loop circuit (hereinafter, referred to as a “PLL circuit”) is used.

Due to the presence of the PLL circuit, the clock of the base station 103 has the same clock except that there is a phase delay due to transmission as compared with the clock of the MCC 102, and the same time can be calculated. It becomes possible.

Clock separation device and channel separation device 3
The output data from 01 is input to the channel board 321. Other communication data is stored in another channel board 321.
Input.

The following operation is executed in the channel board 321. First, output data from the clock separation device and the channel separation device 301 are transmitted to the protocol conversion device 30.
3, the protocol of the transmission path between the MCC and the base station is terminated in the device. Next, this output data is provided to the frame configuration device and the offset correction device 306, and is configured into a frame, which is a unit transmitted in a wireless section in the device.

The output data formed into a frame is subjected to error correction coding such as convolutional coding and interleaving in a channel coding device 309, and is spread to a spreading bandwidth by a spreading modulation device 312. For example, if the symbol rate after error correction is 64 [ksymbols / s],
By spreading this 64 times, the signal is spread to a signal of 4.096 [Mchips / s], that is, a signal having a spreading band of 5 [MHz].

In this spread modulation device 312, FIG.
As shown in (2), double spreading modulation of spreading modulation for channel identification and spreading modulation for base station identification is also performed. Here, the channel identification spreading code is called a short code, and the base station identification spreading code is called a long code.

Of the two types of codes, signal interference from an adjacent base station is suppressed by spreading data with a long code, and multiple access is enabled by spreading with a short code. The long code is assigned a code unique to the base station, and the short code is assigned each time a connection is set.

At the time of inter-sector handover, spread modulation is performed using a long code unique to a base station suitable for communication and a short code individually assigned to each base station. The spread user signal is input to the sector switching device 318 together with another spread user signal. The sector switching device 318 converts the spread user signal into MC
Sector board 32 suitable for communication specified by C102
Switch to 2.

The selected sector board 322 modulates the user signal into a radio frequency band in the carrier modulator 315 and transmits the modulated signal to the mobile station via the transmission / reception antenna device 317.

On the other hand, the clock separated by the clock separation device and the channel separation device 301 is input to the frame period generation device 307, and the frame period is calculated by the counting operation in the frame period generation device 307. The calculated frame period is provided to the sector board 322 via the pilot encoder 310 and the spread modulator 313 in a different system from the user signal.

Here, pilot encoding apparatus 310
A pilot signal is generated through appropriate encoding based on the input frame period. This is spread in the spreading modulator 313 to the spreading band. The pilot signal thus spread is provided to the sector board 322.

The sector board 322 transmits the pilot signal spread as described above to the carrier modulator 315.
, Is modulated into a radio frequency band, and transmitted together with the user signal described above through the transmitting / receiving antenna device 317 into the space as sector information.

(D-1-3) Processing of Mobile Station At the end of the description of the downlink operation, the downlink operation of the mobile station 107 will be described. This operation is a receiving operation.

The spread signal received by the antenna device 401 via the radio channel is demodulated by the carrier demodulator 402 into a signal in a spread band. At this time, the mobile station 107 does not need to recognize whether the number of sectors transmitted from the base station 103 is one or a plurality of sectors.

The spread band signal is further transmitted to the rake receiving device 4
04 and is despread into a baseband signal. Here, the rake receiver 404 corrects the phase rotation due to fading caused by the movement of the mobile station, and combines multipaths generated by reflection of a building or the like in a radio channel to improve reception gain. Having.

The baseband signal from the rake receiver 404 is subjected to error correction processing such as deinterleaving and Viterbi decoding in the channel decoding device 406, and then the frame disassembly device removes symbols such as headers to extract user data.

The user data is input to the information source coding device (decoder) 412, and is converted into a state that can be recognized by the user. For example, in the case of voice, data that is voice-encoded by G729, 32k-ADPCM, or the like is converted into a voice signal that can be recognized by the user.

(D-2) Processing in Uplink Next, the processing operation of each station in the uplink will be described.

(D-2-1) Processing of Mobile Station First, the operation of the mobile station 107 in the uplink will be described. This operation is a transmission operation.

Information from the user is encoded into digital data in an information source encoding (encoder) 414.
When a digital signal is directly input from the user, this conversion operation is unnecessary.

Now, the digitized information is divided into data units suitable for transmission to the radio channel in the frame configuration device 411 and is provided to the channel coding device 408. The channel coding device 408 performs error correction coding such as convolution coding and interleaving on the data, and spreads the data to a spreading bandwidth by the spreading modulation device 405.

The spread band data is transmitted to the carrier modulator 40.
At 3, the signal is modulated up to the radio frequency band and emitted into the radio channel via the antenna device.

(D-2-2) Processing of Base Station Next, an uplink operation in the base station 103 will be described.

The signal is received by the transmission / reception antenna device 317 and the reception-only antenna device 320 via the radio propagation path.
Signals from a plurality of mobile stations are input to carrier demodulators 316 and 319, respectively, and are converted into spread band signals. The signal of the spread band is input to the channel board 321 via the sector switching device 318.

In the channel board 321, the input signal of the spread band is input to the rake receiver 314,
The correction of the phase rotation of the fading and the multipath synthesis are performed together with the despreading, and demodulation is performed to the signal of the base band.

In the above-described receiving operation, when the inter-sector handover is not performed, the transmitting / receiving antenna device 317 and the receiving-only antenna device 320 are used in a pair connected to the same sector and used for antenna diversity. You.

On the other hand, when the inter-sector handover is performed, one of the transmitting / receiving antenna device 317 and the receiving-only antenna device 320 is switched to an antenna connected to a different sector, and is used for sector diversity. .

Here, the channel decoding device 311 performs error correction processing such as deinterleaving and Viterbi decoding, and the radio frame is decomposed by the frame decomposing device 308. In this frame disassembly device 308, the wireless interface is terminated.

The output data of the frame decomposition device 308 is
The protocol is converted by the protocol converter 305 into a transmission protocol between the base station and the MCC. The data subjected to the protocol conversion is multiplexed with other channels by the channel multiplexing device and the clock inserting device 302, a clock is inserted, and M
It is transmitted to CC102.

(D-2-3) Processing of MCC At the end of the description of the operation of the uplink, the operation of the MCC 102 in the uplink will be described.

The multiplexed data transmitted from the base stations 103 and 104 are input to a clock separation device and channel separation devices 213 and 214, respectively, and a clock included in the multiplexed data is separated. The clock separation device and the channel separation devices 213 and 214 synchronize from the extracted clock and separate multiplexed data.

The data on the separated channel passes through the selection / synthesis unit 210 and is input to the route selection unit 207.

Here, the selection / combination device 210 searches the handover memory table 206 for a connection related to handover between base stations, and performs handover of the received data on a radio frame basis at the time of performing the handover of the relevant connection. Get the effect.

The route selection device 207 determines whether the communication partner terminal is a terminal connected to the present system or the external communication network 1
01 to determine if the terminal must be connected via
If the terminal is connected to the present system, it is turned back here and input to the multicast device 205.

On the other hand, the terminal of the communication partner is the external communication network 101
If the terminal has to be connected through the external communication network 1 in the channel multiplexing device 202, the protocol conversion device 204 terminates the protocol of the present system.
The conversion is performed according to the protocol No. 01.

The description of the data flow in the present system has been completed.

(E) Inter-Sector Handover Operation Finally, how each station executing the above-described operation operates as a whole system at the time of inter-sector handover will be described.

(E-1) Operations Required for Inter-Sector Handover Here, the mobile station 109 moves from the sector 117 connected to the base station 103 to the sector 1 connected to the base station 103.
The case where an inter-sector handover to 18 is performed will be described.

When performing an inter-sector handover, the operation required for the downlink is based on the fact that the data transmitted by one system from the MCC 102 to the base station 103 is divided into two sectors 117 and 118 in the base station 103.
It is to be branched into systems.

On the other hand, the operation required on the uplink is to select, from the signals transmitted from the mobile station 109 and received by the two systems of the sectors 117 and 118, those having an appropriate multipath reception state. Select and rake receiver 3
14 is to perform maximum ratio combining.

(E-2) Operation Before Inter-Sector Handover This will be described with reference to FIGS. 9 and 10. However, it is assumed that the pilot signal is transmitted at a constant transmission power by a signal unique to the base station, and that the same short code is assigned to all base stations. 9 and 10, the short code of the pilot signal is expressed as SC # 0, and the long code of the base station 103 is expressed as LC # 0.

Further, during the inter-sector handover, one corresponding channel board is used for communication with one mobile station, so that the downlink channel and the uplink channel in FIGS. 9 and 10 are the same channel, respectively. Boards are used.

FIG. 9 shows a state before the inter-sector handover is performed, that is, a normal communication state.

As shown in FIG. 9, the transmitting base station 103
Is transmitting to the mobile station 109 via the transmission / reception antenna apparatus related to the sector 117. In FIG. 9, the short code used in the downlink channel is represented by SC # N. This SC # N is different from SC # 0 which is a short code of the pilot signal.

On the other hand, the receiving base station 103 receives a transmission signal from the mobile station 109 by antenna diversity reception using a transmission / reception antenna device and a reception-only antenna device. Then, the finger device 6 shown in FIG.
By inputting the received waves despread by 01 and 602 to the combiner 603, they are combined while correcting the propagation delay and output to the rake receiver 314.

Note that only the long code is notified to the mobile station 109 in advance, and the location information of the base station or the sector is not particularly given. The selection of the sector connected to the mobile station 109 and the determination of the sector switching are performed by the sector switching device 318 of the base station 103, and the mobile station 109 is not involved. That is, the mobile station 109
Although the connected base station is recognized, it is not known which sector in the base station is connected.

Here, the procedure of how the base station 103 determines a sector will be described.

The mobile station 109 transmits an uplink random access channel for calling request / call response to the base station 103.

At this time, base station 103 observes and compares the reception power of the uplink random access channel in each sector in matched filters 703 to 705,
Select the sector with the highest received power. Then, using the selection switching device 701, the downlink signal is transmitted to the sector selected by the maximum value determination device 702, and the uplink signal from the mobile station 109 is received in the corresponding sector.

(E-3) Operation for Switching to Inter-Sector Handover Next, the operation for switching sectors will be described.

In the state before the inter-sector handover shown in FIG. 9, mobile station 109 transmits the ratio of the downlink traffic channel reception power to the pilot signal reception power (downlink traffic channel) according to the instruction of base station 103 or at regular intervals. Received power / Pilot signal received power) R
tp is reported to the base station 103.

The value of the power ratio Rtp is, for example, a value that becomes lower when the mobile station 109 departs from the sector to which it is currently connected. This is because the pilot signal is transmitted at the same power from any base station and from any sector, so that the power does not fluctuate, but the downlink traffic channel reception power is from the sector currently used for communication. This is because when the sensitivity decreases, the value decreases.

On the other hand, as described above, the base station 103
The power ratio Rtp is monitored by the selection switching device 701 of the sector switching device 318. And this power ratio R
When it is observed that tp has fallen below a certain threshold,
The reception powers of the other two sectors are also observed, and a sector that can obtain the maximum reception power is searched.

Then, base station 103 transmits the same signal as the signal already transmitted in the sector that has already been transmitted to the sector for which the maximum received power has been observed, by the switching process by sector switching device 318. The demodulated signal received from the sector is transmitted to the rake receiving device 314.

Accordingly, base station 103 adds the received signals for two or more sectors in rake receiving apparatus 314 and performs maximum ratio combining. As a result, the inter-sector handover state shown in FIG. 10 is established.

When the inter-sector handover is in progress, the base station 103 monitors whether or not the power ratio Rtp reported from the mobile station 109 has exceeded a certain threshold (th sec del). Is obtained, the received power in each connection sector is observed.

Then, downlink transmission and uplink reception for the sector having the smallest received power are stopped. As a result, the communication state is as shown in FIG. 9, that is, the state after the inter-sector handover.

The base station 103 causes the mobile station 109 to measure and report the downlink traffic channel reception power in the same manner as the power ratio Rtp, and notifies the MCC 102 of this information. At this time, the MCC 102 determines, based on the information reported from the mobile station 109, that is, the handover memory table 206, whether to perform the inter-base-station handover based on the traffic situation of each base station.

As described above, according to the present embodiment, the CD
Also in the MA communication system, inter-sector handover is realized without interruption of signals.

(F) Effects of Embodiment As described above, according to this embodiment, it is possible to actually make a cell sector even in a CDMA communication system, and to increase the number of mobile stations connected simultaneously per base station. Will be able to

Further, in switching between sectors within the same base station or between different base stations, it is possible to perform soft handover without interrupting communication data,
Good communication quality can be maintained.

Further, since the mobile station can perform simultaneous communication with a plurality of sectors, a diversity effect can be obtained, the reception gain can be obtained in each of the base station and the mobile station, and the transmission power of the base station and the mobile station can be obtained. Can be kept low. As a result, communication interference between the base station and other mobile stations is reduced, and the number of simultaneously connected mobile stations per sector can be increased.

Furthermore, since the inter-sector handover is performed prior to the inter-base station handover, it is possible to prevent a reduction in transmission efficiency between the MCC and the base station.

Further, the CDMA communication system according to the present embodiment can be dealt with only by the change on the base station side and does not involve the change on the mobile station side, which is advantageous in realizing the system.

(G) Other Embodiments In the above embodiment, a case where one cell is divided into three sectors has been described. However, the number of divisions may be two or four or more. Applicable. As described above, the number of the sector boards provided in the base station may be the same as the number of the sector boards.

In the above-described embodiment, a case has been described in which an exclusive OR circuit is used as a multiplier in the spread modulation device 312. However, a circuit that performs a multiplication operation according to another rule may be applied.

[0136]

As described above, according to the first aspect of the present invention, at the time of call setup, the detection output of the access signal transmitted from the mobile station device which has requested a call or responded to the call request. Is determined for each sector, and a sector suitable for communication with the mobile station device is selected from the comparison results, so that information about a sector suitable for communication is not given from the mobile station device side. An appropriate sector can be specified on the base station device side.

According to the second aspect of the present invention, when the reception state of the mobile station apparatus side decreases during communication, a detection output of a transmission signal transmitted from the mobile station apparatus is obtained for each sector. From these comparison results, a sector suitable for communication with the mobile station device is selected, and both the newly selected sector and the sector already used for communication are used until a good reception state is recovered thereafter. By selecting a sector to be used for communication, soft handover without fear of interruption of communication data can be realized.

If information on the ratio of the received power of the traffic channel to the received power of the pilot signal is used as the reception status information, it is not necessary to recognize which sector the mobile station apparatus is moving to which sector. The execution timing of the soft handover can be reliably executed.

Further, according to the third invention, for the sectors in the cell under the jurisdiction, the user data is spread-coded with the same spread code regardless of the difference between the sectors.
The number of spreading codes to be used can be reduced as compared with a case where a different spreading code is attached to each sector.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an outline of a CDMA communication system according to an embodiment.

FIG. 2 is a diagram illustrating a planar arrangement example of base stations and sectors.

FIG. 3 is a block diagram illustrating a configuration example of an MCC.

FIG. 4 is a block diagram illustrating a configuration example of a base station.

FIG. 5 is a block diagram illustrating a configuration example of a spread modulation device.

FIG. 6 is a block diagram illustrating a configuration example of a rake receiving device.

FIG. 7 is a block diagram illustrating a configuration example of a sector switching device.

FIG. 8 is a block diagram illustrating a configuration example of a mobile station.

FIG. 9 is a diagram illustrating a state before and after a handover between sectors.

FIG. 10 is a diagram illustrating a state during handover between sectors.

[Explanation of symbols]

101: communication network, 102: MCC (mobile communication control station),
103 to 105: base station, 106 to 109: mobile station, 1
10 to 112 cells, 113 to 115 directional antenna devices, 116 to 119 sectors, 318 sector switches, 321 channel boards, 322 sector boards,
312: Spread modulator, 510: Spread modulator for channel identification, 530: Spread modulator for base station identification, 511
Spreading code generator for channel identification, 531 ... Spreading code generator for base station identification, 701 ... Selection switching device, 702 ... Maximum value judging device, 703-705 ... Matched filter.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H04Q 7/36 H04B 7/26 109N 7/38 H04J 13/00 A H04J 13/00 H04L 1/00 7/00

Claims (4)

[Claims] 1. A mobile station apparatus, which is spread-coded using one or more mobile station apparatuses and a code division multiple access communication scheme in at least one or more sectors among at least two or more sectors in a serving cell. A base station for communicating user data, comprising: a receiving means provided for each sector, the access signal being transmitted from a mobile station device that has requested a call or responded to the call request when setting up a call. And a plurality of correlation detection means for separately detecting each received signal and comparing detection outputs of the plurality of correlation detection means to select a sector suitable for communication with the mobile station apparatus. A base station apparatus comprising: 2. At least one or more sectors among at least two or more sectors in a serving cell are spread-encoded with one or more mobile station devices using a code division multiple access communication system. A base station device that communicates user data, and from reception status information notified from a mobile station device that is communicating,
When detecting a decrease in the reception state of the mobile station device side, the transmission signal transmitted from the mobile station device is separately received by the receiving means prepared for each sector,
A plurality of correlation detection means for performing correlation detection on each of the received signals, and a detection output of the plurality of correlation detection means are respectively compared to select a sector suitable for communication with the mobile station apparatus and newly select the sector. Base station apparatus comprising a selection switching unit for selecting both of the selected sector and a sector already used for communication as a sector to be used for communication until a good reception state is recovered thereafter. . 3. The reception status information according to claim 2,
A base station apparatus comprising information on a ratio of a traffic channel reception power to a pilot signal reception power. 4. At least one or more of the at least two sectors in the serving cell are spread-coded using one or more mobile station devices and a code division multiple access communication system. A base station apparatus for communicating user data, comprising: a sector in a cell under its jurisdiction, comprising: a spread modulation means for spreading and coding user data with the same spreading code regardless of a difference between sectors. Base station device.