JP2001145153A - Base station and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a high communication quality at processing of multiplexing of received waves. SOLUTION: In a base station provided with a conversion processing means which generates an outgoing channel signal by receiving and converting unit signals the receiving timing of which respectively fluctuates, there are provided a reference transmitting timing recognizing method which recognizes the reference transmitting timing set correspondingly to a plurality of base stations which transmits the outgoing channel signal, so that the outgoing channel signal having the same content may be received at a mobile station in the same phase and a unit signal discriminating means which abandons unit signals, the receiving timing of which is delayed to such a degree that the outgoing channel signal is not able to be transmitted at the reference transmitting timing of the unit signals and supplies the unit signals at the receiving timing of which the outgoing channel signal can be transmitted at the reference transmitting timing to the conversion processing means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system, for example, using an asynchronous transfer mode (ATM) communication between a base station control station and a base station, and receiving A in the ATM communication.
The present invention can be applied to a case where soft handoff is performed in a CDMA (Code Division Multiple Access) mobile communication system in which information obtained from a TM cell is wirelessly transmitted to a mobile station by a base station.

[0002] The present invention also relates to a base station as a component of such a communication system.

[0003]

2. Description of the Related Art A wireless communication system 10 using a CDMA system is shown in FIG.

The system 10 includes a mobile terminal (mobile station) 11 equipped with a rake (RAKE) receiver and the mobile station 11
Base stations 12 and 13 capable of accommodating the two base stations 1 and 2
And a base station control station 14 for controlling a plurality of base stations including the base stations 2 and 13. It is also assumed that the base station 12 covers the area E1 and the base station 13 covers the area E2.

In the radio communication system 10 using the CDMA system, the same frequency can be used in the adjacent areas E1 and E2, so that the mobile station 11 can perform site diversity.

In the site diversity, for example, when the base station 11 moves along the locus indicated by the arrow M1, when the base station 11 is located in the overlapping area of the areas E1 and E2 during the movement, the base station 11 has been wirelessly connected. Base station 1
2 and the base station 13 to be connected to the base station 13 from both of them, and both downlink channel signals can be used for communication.

Further, a mobile station 11 equipped with a rake receiver
By performing this site diversity, it becomes possible to realize soft handoff.

In the soft handoff, the mobile station 11 communicates with both the new and old base stations (in this case, the base stations 13 and 12) at the same time, and moves with the old base station 1 in the direction of arrow M1.
2 to the new base station 13 to smoothly and instantaneously switch communication partners.

At this time, the internal processing of the mobile station 11 includes:
It is only necessary to perform the maximum ratio combining method (Maximal-RatioCombining).

In the maximum ratio combining method, two base stations 12, 1
3 to maintain high communication quality by performing weighting according to the reliability and synthesizing them in phase. However, in order to perform the maximum ratio combining and combine in phase, downlink channel signals having the same information content coming from the two base stations 12 and 13 need to be received by the mobile station 11 in phase.

On the other hand, the information that is the source of the downlink channel signal wirelessly transmitted from each of the base stations 12 and 13 is transmitted through the wired transmission path C.
1, the base station controller 14 by ATM communication using C2.
Supplies. ATM communication has superior features compared to STM (synchronous transfer mode) communication, such as accommodating communication between terminals having greatly different communication speeds, and accommodating communication whose communication speed varies greatly during communication. Therefore, the ATM communication is employed in the wireless communication system 10.

The base stations 12 and 13 which have received the ATM cell by the ATM communication disassemble the header of the ATM cell, extract only information bits (cell data, ie, information contents), and obtain a bit block (base station) having a frame length of 20 ms. Reconstructed into a data frame for wireless communication between a station and a mobile station (ie, a wireless frame), and wirelessly transmits the wireless frame as the downlink channel signal.

The base stations 12 and 13 are connected to a GPS (Glob)
al Positioning System) Since a reference clock is obtained from a satellite, a wireless frame having the same contents of cell data can be wirelessly transmitted at a mutually synchronized transmission timing T1 as shown in FIG.

In FIG. 2, an ATM cell having cell data of information content # 1 is transmitted from the base station control station 14 to the wired transmission lines C1 and C2 at time t11, and then transmitted at time t11.
12 and is received by the base station 12 at time t13.
Is received.

Since both the times t12 and t13 have sufficient time before the transmission timing T1, the base station 12
In and 13, the wireless frame (# 1) having the information content # 1 can be wirelessly transmitted at the transmission timing T1.

Therefore, the mobile station 11 that has received the radio frame (# 1) transmitted from the base station 12 and the radio frame (# 1) transmitted from the base station 13 in the same phase normally executes maximum ratio combining. can do.

[0017]

In a radio communication system 10 using ATM communication between a base station control station and a base station, a plurality of base stations 12 and 13 are basically connected to a mobile station 11 in a soft handoff state. At the time (for example, the time t11) at which the same cell data (for example, the # 1) can be transmitted at the same timing (for example, the T1), the base station control station 14 sends an ATM cell (data frame) to each of the base stations 12 and 13. Send

However, depending on conditions such as the degree of congestion of the transmission lines C1 and C2, variations in transmission time, that is,
Due to the fluctuation, the timing of reception at the base station 12 or 13 is delayed, so that the two base stations 12, 1
In both cases, it is not always possible to wirelessly transmit a radio frame including the information content of the cell data at a desired timing.

For example, the information content # 2 shown in FIG. 2 is transmitted from the base station control station 14 at time t21, and then received by the base station 12 at time t22 and transmitted at the transmission timing T2.
By the time the base station 13 has received the information content # 2 at a time t23 later than the time t22, the base station 13 has already reconfigured the wireless frame (# 2) by the time t1, the transmission frame T2 still has the wireless frame (# 2). # 2) The reconfiguration has not been completed.

In this case, at the transmission timing T2,
Since it is impossible for the base station 13 to transmit a radio frame having the information content # 2, the mobile station 11 transmits the information content # 2.
For 2, the maximum ratio combining cannot be performed.

In addition, an unrelated frame (# 2) having the information content # 2 that was not in time for the transmission timing T2
Is transmitted by the base station 13 at the next transmission timing T3, and the wireless frame corresponding to the cell data of the subsequent ATM cell is also sequentially transmitted by radio.

The transmission of the radio frame (# 2) has already been completed at the other base station 12, and the radio frame (# 3) having the following information content # 3 is transmitted at the transmission timing T3. Therefore, in the site diversity of the mobile station 11, the radio frame (# 2) arriving from the base station 13 and the radio frame (# 3) arriving from the base station 12 are simultaneously received and combined at the maximum ratio. This is because wireless frames having different information contents will be sequentially synthesized.

When radio frames having different information contents are combined, the communication quality is remarkably deteriorated, and the communication quality may be even worse than when no site diversity is performed.

As a countermeasure against such a problem, the mobile station 11
Base stations 1 to perform normal maximum ratio combining in
In order to synchronize the transmission timings of radio frames containing the same information contents, the following methods have been proposed for 2 and 13.

A number is assigned to each radio frame transmitted by the base stations 12 and 13, and the mobile station 11 that has received the radio frame checks the number before combining and aligns the correspondence between the radio frames, and Perform maximum ratio combining.

One base station (for example, the base station 12) checks the number of the radio frame, notifies the other base station (for example, the base station 13) of the number of the radio frame to be transmitted. , The correspondence of the radio frames is aligned.

However, according to the method, since the confirmation of the number is performed before the maximum ratio combining is performed, it is erroneously recognized that the corresponding number does not correspond, or it is determined that the corresponding number does not correspond. There is a possibility of misunderstanding. Since the received signal power is unstable at the time of handoff, there is a high possibility that such erroneous recognition will occur. In the maximum ratio combining performed under the misperception, wireless frames having different information contents are combined, so that communication quality is significantly deteriorated.

In the case of the method, communication for notifying the number must be performed, and a plurality of base stations 12 and 13 are required.
In addition, complicated control by the base station control station 14 is required.
Further, if the numbers are shifted, neither the base station 12 nor the base station 13 can transmit a radio frame until the numbers match, so that the mobile station 11 cannot receive the information content itself (for example, # 1) at all. This impairs the real-time communication. This is a serious problem in communication where real-time performance is important such as voice communication.

Furthermore, in the method, when the numbers are shifted,
In order to eliminate the deviation, it is necessary to perform a correction process of a complicated procedure.

[0030]

In order to solve the above-mentioned problems, according to the present invention, a mobile station combines or selects received waves of downlink channel signals arriving from a plurality of base stations in the same phase. A base station as a component of a communication system for performing a selection process, wherein a fluctuation caused in a process of being transmitted and transmitted from a higher-level station is varied for each unit signal, and the unit signal is received and converted. In the base station provided with a conversion processing means for generating a signal, so that the downlink channel signal of the same content is received in phase in the mobile station, corresponding to a plurality of base stations transmitting the downlink channel signal A reference transmission timing recognizing means for recognizing a reference transmission timing to be set; and a receiving channel of the unit signal whose reception timing is set to the reference transmission timing. Unit signal delayed that it can not send a signal to discard processing unit signals that can send downlink channel signal to the reference transmission timing, characterized in that it comprises a unit signal discrimination means for providing to said conversion processing means.

The communication system according to the present invention further includes a mobile station that performs a predetermined received wave combining / selecting process of combining or selecting received waves of downlink channel signals coming from a plurality of base stations in phase. And a base station.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (A) Embodiment Hereinafter, a case where the base station and the communication system of the present invention are applied to a CDMA wireless communication system for performing ATM communication between a base station control station and a base station will be described as an example. An embodiment will be described.

The base station according to the present embodiment discards ATM cells whose reception timing is delayed from the transmission timing common to a plurality of base stations so that a downlink channel signal cannot be transmitted among the ATM cells transmitted from the base station control station. Then, for only ATM cells that can transmit downlink channel signals at the common transmission timing, the cell data is accommodated in a radio frame and transmitted wirelessly.

Since the delay in the reception timing of the ATM cell in the base station occurs for each base station and each ATM cell, for example, even if the reception timing of the ATM cell is once delayed in one base station (base station 12), the other base station is delayed. It should be noted that the reception timing is not always similarly delayed in the station (base station 13), and that the subsequent ATM cells are not similarly delayed in the base station (base station 12) whose reception timing is delayed. By doing so, the present embodiment is configured.

In a system using STM communication for data transmission between a base station control station and a base station, the same data is always transmitted from a plurality of base stations by sequentially processing data received by the base stations. However, if the delay occurs in the reception timing of one STM frame, considering that the same delay occurs in all STM frames subsequent to the STM frame, it is a characteristic point of the ATM communication. It can be said that there is.

(A-1) Configuration of the Embodiment FIG. 3 shows the configuration of the wireless communication system 20 of the present embodiment. The wireless communication system 20 corresponds to the wireless communication system 10. Specifically, the wireless communication system 20 may be a mobile telephone system.

The difference between the wireless communication system 20 of the present embodiment and the wireless communication system 10 is that the base station 2
There are only 2 and 23 functions. Accordingly, FIG. 3 shows the conventional wireless communication system 10 and also shows the wireless communication system 20 of the present embodiment.

In FIG. 3, a radio communication system 20 includes a mobile station 11 equipped with a rake receiver, base stations 22 and 23 capable of accommodating the mobile station 11, and the two base stations 2
And a base station control station 14 for controlling a plurality of base stations including the base stations 2 and 23.

It is assumed that the base station 22 covers the area E1 and the base station 23 covers the area E2.

That is, the base station 22 corresponds to the base station 12, and the base station 23 corresponds to the base station 13.

It should be noted that, among the components of the radio communication system 20, those having the same reference numerals as those of the radio communication system 10 have the same functions as those of the components of the radio communication system 10. ing.

That is, the components 11, 14, C1, C
2, E1, E2, and M1 have the same functions in the wireless communication system 20 and the wireless communication system 10.

The base station 22 of the wireless communication system 20 has an internal configuration shown in FIG.

(A-1-2) Internal Configuration of Base Station In FIG.
4, a baseband processing unit (BB) 25, a wireless transmission unit 26, and a clock reception unit 27.

The format conversion device 24 includes a reception unit 31, a discard conversion unit 28, a transmission unit 29, and a control unit 30.

The receiving section 31 is a section for receiving and holding the ATM cells AC from the base station control station 14 via the wired transmission path C1.

The discard converter 28 decomposes the header of the ATM cell AC received by the receiver 31, extracts only information bits (cell data), and reconstructs it into a bit block (the radio frame) having a frame length of 20 ms. As described later, each time a data transfer command TI of a fixed period is supplied from the TI generator 32 in the control unit 30 as described later, the reconstruction of the radio frame WF has been completed almost at the time of the supply. In this case, the wireless frame WF is supplied to the transmission unit 29, and when the reconstruction of the wireless frame WF is not completed at the time of the supply, the cell data serving as the basis for the reconstruction is discarded. have.

For example, in the case of a data rate of 9600 bps, the configuration of the radio frame WF includes a header of 1 or 4 bits, 171 or 168 bits of information bits composed of information contents corresponding to cell data, and a frame. 12-bit CRC (Cyclic Redundancy Check: Cycl used as quality identifier)
ic Redundancy Check) and 8-bit tail bits (Tail Bits).

Also, for example, a data rate of 14400 bp
In the case of s, the radio frame WF includes a 1- or 5-bit header, 266 or 262-bit information bits composed of information contents corresponding to cell data, 1-bit reserved bit (Reserved Bit), and a frame. It may be composed of a 12-bit CRC used as a quality identifier and 8-bit tail bits.

A radio frame having such a structure is 2
It is supplied to the baseband processing unit 25 via the transmission unit 29 at every 0 ms transfer timing.

The transmission section 29 is a section that outputs the radio frame WF to the baseband processing section 25 at the timing of supplying the radio frame transfer command WI supplied from the control section 32. Since the wireless frame transfer instruction WI corresponds to the common transmission timing (for example, T1 or the like), the fluctuation (the discard conversion unit 2) generated in the transmission and processing up to this point is performed.
8 is a small fluctuation that does not cause the disposal to be performed)
It is absorbed in the transmission unit 29.

The baseband processing unit 25 encodes the supplied radio frame WF in radio frame WF units, performs spread modulation, and outputs the result to the radio transmission unit 26.

The radio transmitting section 26 is a section for converting the coded and spread-modulated radio frame WF into a prescribed frequency band and transmitting the radio frame WF.

Further, the clock receiving unit 27 has a GPS
This section receives a reference clock from a satellite and detects a common transmission timing that is a common transmission timing synchronized with another base station (for example, the base station 23).

The common transmission timing is, for example, GPS
A signal having a fixed period obtained by dividing the frequency of the clock supplied from the satellite is supplied from the clock receiving unit 27 to the TI generating unit (data transfer instruction generating unit) 32 in the control unit 30.

The TI generator 32 generates a data transfer command TI each time the common transmission timing is supplied, and outputs the data transfer command TI to the discard converter 28. Therefore, this data transfer instruction TI is output at the same cycle as the common transmission timing.

It is assumed that the base station 23 has the same internal configuration as the base station 22.

Next, the internal configuration of the discard converter 28 will be described with reference to FIG.

(A-1-2) Internal Configuration of Discard Conversion Unit In FIG. 1, the discard conversion unit 28 includes a reconfiguration unit 35 and a discard determination unit 36.

The reconfiguration unit 35 receives the ATM cell AC from the reception unit 31 and converts it into the radio frame W.
In the case where the discard command DI is not supplied from the discard determination unit 36 during the reconfiguration, a reconfiguration completion notification RC indicating the completion of the reconfiguration is supplied to the discard determination unit 36. Then, the reconfigured wireless frame WF is output to the transmission unit 29 at the time of completion of the reconfiguration.

Due to the fluctuation of the ATM cell AC, generally, at the time of the completion of the reconfiguration, the base station (for example, the base station 22,
23), but this variation is absorbed by the transmission unit 29 in the next stage as described above.

In a normal communication state in which the fluctuation is small and the ATM cells AC are continuously supplied at substantially constant intervals via the wire transmission line C1, the reconfiguration unit 35 periodically performs the same period as the data transfer command TI. Then, the operation of generating the wireless frame WF and outputting it to the transmitting unit 29 can be repeated, and during that time, the discard command DI is not output.

However, when the fluctuation is large and the discard command DI is supplied, the reconfiguration unit 35 ignores the storage contents such as the cell data in the middle of the reconfiguration, abandons the reconfiguration of the radio frame, and discards it. Execute the process. If the reconstructing unit 35 receives the discard command DI and is not in the process of executing the reconfiguration processing and does not store the cell data or the like, the reconfiguration unit 35 does not need to perform anything. DI
, The timing at which the TI generation unit 32 outputs the data transfer instruction TI can be recognized.

On the other hand, the discard judging section 36
If the reconfiguration completion notification RC is not received before the supply of the data transfer instruction TI from the
Is a part that outputs the discarding command DI to the reconfiguration unit 35 when receiving

In the case of the normal communication state, since the supply of the reconfiguration completion notification RC, which is performed almost periodically, is earlier than the supply of the data transfer instruction TI, which is performed periodically, the discard determination unit 36 determines The state in which the discard command DI is not output continues.

However, for this purpose, the difference between the reception timings of the ATM cells between the base station 22 and the base station 23 (ATM
The size of the cell fluctuation) is sufficiently shorter than the interval between adjacent common transmission timings (for example, the interval between T1 and T2 in FIG. 5) and the ATM cell AC having the same information content.
Is not received in different timing sections (for example, the timing sections TD1 and TD2 in FIG. 5) at the base stations 22 and 23.

The precondition is, for example, that the base station control station 1
4 also receives the reference clock supplied from the GPS satellite, and the base station control station 14 determines that the timing section (TD1)
ATM cell reception timing (for example, time t12) of the base stations 22 and 23 at the earliest possible time position (the leftward in FIG. 5).
It can be easily satisfied by transmitting the cell AC.

Hereinafter, the operation of the present embodiment having the above configuration will be described.

(A-2) Operation of the Embodiment FIG. 5 shows the operation of the wireless communication system 20 of the embodiment.
Has the same appearance as FIG. 2 described above.

That is, in FIG. 5, the base station control station 1
4 is such that the base stations 22 and 23 can transmit the radio frame WF having the same cell data at the same common transmission timing to the mobile station 11 in the soft handoff state as long as the fluctuation of the ATM cell AC is not larger than the allowable range. At a time (for example, time t11), the ATM cells AC having cell data of the same information content (for example, # 1) are transmitted to the respective base stations 22 and 23.
Send

The interval between adjacent common transmission timings (eg, T1 and T2) in FIG. 5, that is, the length of the timing interval (eg, TD1) is constant.

That is, the common transmission timings T0 and T1
Between the timing interval TD1 and the common transmission timing T1
The timing interval TD2 between the common transmission timings T2 and T2, the timing interval TD3 between the common transmission timings T2 and T3, and the timing interval TD4 between the common transmission timings T3 and T4 have the same time width.

The time is earlier in the left of FIG. 5 and later in the right.

Therefore, the base station control station 14 sets the information content {
The transmission timing of the ATM cell AC (# 1) having a value of "1" is determined when the cell rate in the wired transmission path (for example, the wired transmission path C1) is the highest.
May be such that the ATM cell AC (# 1) can be received immediately after the common transmission timing T0 (that is, a position near the right side of T0).

In FIG. 5, the time t11 corresponding to the transmission timing is located on the right side of the common transmission timing T0. However, when it is expected that the fluctuation of the ATM cell AC is large, the time t11 is set to the common transmission timing. Timing T
By setting the time t11 to the time position on the right side of T0 and closer to T0 by locating the time t11 on the left side of 0, the allowable range of fluctuations is expanded, and it is possible to cope with even larger fluctuations. It is preferred.

When transmitting the ATM cell AC (# 1) at the transmission timing t11 such that the base station can receive the ATM cell AC (# 1) immediately after the common transmission timing T0, the time substantially equal to the timing interval TD1 The width is the permissible range.

If the fluctuation of ATM cell AC (# 1) is within the allowable range, the base station can wirelessly transmit radio frame WF (# 1) having information content # 1.

In the case of FIG. 5, the allowable range is the time T
It is set to be smaller than the difference between 1 and t11 and equal to or larger than the difference between T1 and t12, and smaller than the timing interval TD1.

The same applies to timing sections TD2 to TD4 other than timing section TD1.

In FIG. 5, ATM cell AC (# 1) transmitted from base station control station 14 at time t11 is transmitted through wired transmission lines C1 and C2, and received by base station 22 at time t12. It is received by the base station 23 at t13.

Since both times t12 and t13 have enough time to perform the reconfiguration processing before the common transmission timing T1, in the base stations 22 and 23, before the discard judging section 36 outputs the discard command DI, Reconfiguration completion notification R
C is output, and the wireless frame WF (# 1) having the information content # 1 is supplied to the transmission unit 29.

The transmission unit 2 transmits the radio frame WF (# 1)
At the time of supply to the ATM 9 between the base stations 22 and 23.
Although there is usually a variation due to the fluctuation of the cell AC, the variation is absorbed by the transmitting unit 29 that operates according to the wireless frame transfer command WI synchronized between the base stations 22 and 23.

Therefore, the wireless frame WF (# 1)
Passes through a baseband processing unit 25 and a wireless transmission unit 26,
Radio transmission is performed from both the base stations 22 and 23 at the common transmission timing T1.

In this case, the mobile station 11 can receive the radio frame WF (# 1) transmitted from the base station 22 and the radio frame W (# 1) transmitted from the base station 23 in the same phase, and normally receive the maximum value. Ratio combining can be performed.

Information content transmitted from base station control station 14 at time t21 following ATM cell AC (# 1)}
ATM cell AC (# 2) having the ATM cell A
Similarly to C (# 1), the signal is transmitted via the wired transmission lines C1 and C2, received by the base station 22 at time t22, and received by the base station 23 at time t23.

The time t22 at the base station 22 is a reception time at which there is enough time to perform the reconfiguration processing before the common transmission timing T2.
Is a reception time at which the time to complete the reconfiguration becomes time tRC, which is later than the common transmission timing T2, if the reconfiguration process is performed to the end.

Therefore, in this case, the discard judging unit 36 which has received the data transfer command TI in the base station 23
Has not received the reconfiguration completion notification RC at that time, and therefore outputs the discard command DI.

Then, upon receiving the discard command DI, the reconfiguration unit 35 sets the radio frame WF (#
Since the reconfiguration processing of 2) is abandoned and the discard processing for the reconfiguration processing is executed, at the common transmission timing T2, the radio frame (# 2) is transmitted from the base station 22 by radio, but the base station 23 From the radio frame (♯
The wireless transmission of 2) is not performed.

Therefore, the mobile station 11 receives the radio frame (# 2) only from the base station 22.

Next, the AT transmitted from the base station control station 14
The information content of the cell data of the M cell AC is $ 3. $ 3
Is data having a semantic content that is consecutive between $ 1 and $ 2 in the order of $ 1, $ 2, and $ 3.

The ATM cell AC (# 3) transmitted from the base station control station 14 at time t31 is received by the base station 22 at time t32 and received by the base station 23 at time t33.

Since both times t32 and t33 are reception times that allow sufficient reconstruction processing before the common transmission timing T3, the radio frame WF (# 3) Data transfer instruction TI
Before the is output, the reconfiguration completion notification RC is output, and both the base stations 22 and 23 wirelessly transmit the radio frame (# 3).

Therefore, the mobile station 11 can receive the radio frame WF (# 3) transmitted from the base station 22 and the radio frame W (# 3) transmitted from the base station 23 in the same phase and return to normal. Maximum ratio combining can be performed.

The same operation is performed at the subsequent common transmission timing (T4 etc.).

After all, in the radio communication system 20,
At most common transmission timings excluding the common transmission timing T2 and the like in which the fluctuation of the ATM cell AC is too large, the base stations 22 and 23 wirelessly transmit the radio frame WF having the same information content. Since the mobile station 11 can perform normal maximum ratio combining,
It is possible to prevent the influence of the fluctuation of the TM cell AC from spreading to all subsequent common transmission timings, and to obtain high communication quality as a whole.

(A-3) Effects of the Embodiment As described above, according to the embodiment, even under the influence of the fluctuation of the ATM cell, the high communication quality at the time of the soft handoff is efficiently maintained by the simple control. be able to.

That is, in the present embodiment, the mobile station at the time of soft handoff does not receive radio frames of different information contents from a plurality of base stations, so that radio frames of different information contents are synthesized to significantly improve communication quality. Can be prevented from deteriorating.

In this embodiment, since the base station does not transmit the radio frame when the fluctuation of the ATM cell is too large, the interference to the mobile stations other than the mobile station during the soft handoff is temporarily reduced. Can be smaller.

Further, in the present embodiment, since the communication quality is not deteriorated due to misrecognition of the corresponding number as in the above method, and there is no connection with the lack of real-time property and complicated correction processing as in the above method, It has a simple and efficient configuration. Considering this point, the present embodiment is considered to be particularly advantageous when applied to a service that requires real-time properties such as a voice service.

(B) Other Embodiments In the above embodiment, the communication between the base station control station and the base station is ATM communication, but these may be other communication systems. For example, packet communication can be used. This is because whether or not the packet transmission can meet the common transmission timing is determined on a packet-by-packet basis according to the fluctuation of each packet.

In the above-described embodiment, whether the discard processing is performed extremely simply is determined only by determining whether or not the reconfiguration of the radio frame is completed at the time when the data transfer instruction TI is supplied at a fixed cycle. It was determined. This is because the processing time required for the radio frame reconfiguration processing is the longest among processing systems that start from the receiving unit 31, pass through the discard conversion unit 28, the transmitting unit 29, and the baseband processing 25, and end at the wireless transmitting unit 26. Or because it has the largest fluctuation range.

Therefore, when there is another processing block having a long processing time and a large fluctuation width comparable to the discard conversion unit 28 in the processing system, a configuration taking the existence of the processing block into consideration is adopted. There is a need to.

Further, in the above-described embodiment, the radio frame to be subjected to the maximum ratio combining is wirelessly transmitted from two base stations 22 and 23 in a normal communication state, but the number of base stations is three or more. There may be.

In the above embodiment, the reception time (for example, times t12 and t13) has been described as a time at which there is enough time to perform the reconfiguration processing before the common transmission timing (for example, T1). Is not necessarily sufficient. This is because, depending on the internal state of the circuit, whether or not it is in time for the common transmission timing may be delicate inside the electronic circuit constituting the actual reconfiguration unit 35 and the like.

For example, the reception time (for example, time t1
2, t13), the common transmission timing (for example, T
The reference reception timing is set as a timing at which the reconfiguration processing can be sufficiently performed by 1). If the reception time is earlier than the reference reception timing, the discard processing is not performed. It is also possible to adopt a configuration in which the operation is performed.

In this case, the processing capacity of the base station can be reduced more than in the above embodiment by eliminating the waste of discarding cell data and the like that have been partially reconstructed, but the reference reception timing is sufficiently early. Since the time has to be set, the possibility that the frequency at which the mobile station can perform normal maximum ratio combining increases, and the communication quality is disadvantageous as compared with the above embodiment in terms of communication quality.

In the above embodiment, the maximum ratio combining method is used as the method of combining received waves, but the combining method of the present invention is not limited to this.

For example, an equal gain combining method (Equal-Gain Com
bining) can be expected to be effective.

Furthermore, the received wave combining / selecting process of the present invention is not limited to such a combined type process, and can be applied to a selective type process.

For example, a certain effect can be expected also when applying a selection combining method (Selection Combining) for selecting a reception wave having the highest reception level among a plurality of reception waves received in phase.

However, in this case, the handoff is a hard handoff, and the mobile station 11 does not need to be equipped with a rake receiver.

In the above embodiment, for simplicity,
Although the description has been made assuming that the ATM cell AC and the radio frame WF have a one-to-one correspondence, the invention is not necessarily limited to this.

For example, when the cell data of one ATM cell is accommodated in two radio frames, if the reconfiguration of one radio frame is in time for the common transmission timing, the 1
Only the radio frame may be transmitted, and the other radio frame may be subjected to discard processing, or both may be discarded. The same applies to the case where one ATM cell corresponds to three or more radio frames.

Further, the configuration of the radio frame is not limited to that described in the above embodiment.

In the above embodiment, the common transmission timing is detected by receiving the reference clock from the GPS satellite. However, this reference clock is output from another clock generation source. It may be.

For example, the clock generation source may be mounted on a base station control station.

That is, the present invention provides a base station as a component of a communication system in which a mobile station performs a predetermined received wave combining / selecting process of combining or selecting received waves of downlink channel signals coming from a plurality of base stations in phase. A base station comprising a conversion processing means for generating a downlink channel signal by receiving and converting a unit signal in which fluctuation occurring during a process of being transmitted and transmitted from an upper station varies for each unit signal; , And the communication system.

[0118]

As described above, according to the present invention, even under the influence of unit signal fluctuation, high communication quality at the time of reception wave combining / selection processing can be efficiently maintained by simple control. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an internal configuration of a discard conversion unit used in a wireless communication system according to an embodiment.

FIG. 2 is an operation explanatory diagram showing an operation of a conventional wireless communication system.

FIG. 3 is a schematic diagram illustrating a configuration of a wireless communication system according to a related art and an embodiment.

FIG. 4 is a schematic diagram showing an internal configuration of a base station used in the wireless communication system of the embodiment.

FIG. 5 is an operation explanatory diagram showing an operation of the wireless communication system of the embodiment.

[Explanation of symbols]

10, 20: wireless communication system, 11: mobile station, 12,
13, 22, 23 ... base station, 14 ... base station control station, 24
.. A format conversion device, 28 a discard conversion unit, 29 a transmission unit, 30 a control unit, 31 a reception unit, 32 a TI generation unit, 36 a discard determination unit.

Claims (2)

[Claims] 1. A base station as a component of a communication system in which a mobile station performs a predetermined received wave combining / selecting process of combining or selecting received waves of downlink channel signals coming from a plurality of base stations in phase. A base station having a conversion processing means for generating the downlink channel signal by receiving and converting a unit signal in which a fluctuation generated in a process of being transmitted and transmitted from the upper station varies for each unit signal; Reference transmission timing recognition means for recognizing a reference transmission timing set corresponding to a plurality of base stations transmitting the downlink channel signal, so that the downlink channel signal is received in the mobile station in phase. Among the unit signals, a unit signal whose reception timing is so delayed that the downlink channel signal cannot be transmitted at the reference transmission timing is discarded, and Unit signal that can send downlink channel signal to a reference transmission timing, the base station characterized by comprising a unit signal discrimination means for providing to said conversion processing means. 2. A mobile station which performs a predetermined received wave combining / selecting process of combining or selecting received waves of downlink channel signals coming from a plurality of base stations in phase, and a base station according to claim 1. A communication system characterized by the following.