JP2002204193A - Mobile communication system - Google Patents

Abstract

(57) [Problem] To provide a mobile communication system capable of spatially separating transmission paths and accommodating many mobile stations with a small number of channels. A base station forms a multi-beam pattern to which different known pilot signals are allocated,
This beam is received and each delay profile is measured and stored for each pilot signal. The base station transmits information on the same channel with different beams optimal for each mobile station, and the communication mobile station receives this beam, measures a received signal delay profile, and determines an optimum beam for the communication mobile station. When # 3, the received signal delay profile of the beam received by the communication mobile station is multiplied by the stored delay profile of # 3, while the other interference beams
The arithmetic processing of dividing by the storage delay profile for # 2 and # 4 is performed and output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system that accommodates many mobile stations with a small number of channels in multi-beam communication.

[0002]

2. Description of the Related Art FIG. 11 shows an access system of a base station having multiple beams. Here, 102 denotes a base station, 103 denotes a mobile station (note that there are a plurality of mobile stations), and the base station forms a multi-beam pattern 101 of different information addressed to each mobile station at the same frequency. Communication is performed with each mobile station using an optimal beam. 104 is the optimal propagation path, here shows the case of a direct wave from beam # 3,
Reference numeral 105 denotes a building reflected wave arriving from a beam other than the optimal beam.
Also, the reflected wave 105 is an interference wave.

As shown in FIG. 11 (a), when a base station selects an optimal beam for each mobile station using multi-beams and carries information by carrying information of each mobile station on the beam, each base station performs a communication. As the beam pattern becomes narrower, interference from other beams enters more strongly, and communication quality deteriorates. A specific example is shown in FIG. When transmission is performed only from beam # 3 as shown in this figure, transmission of very high quality is possible, but another information (that is, information for another mobile station) is transmitted by beam # 2. Is transmitted, the reflected wave from beam # 2 is received by the mobile station, and the received wave is obtained by multiplying the original information from beam # 3 by the interference wave (reflected wave) from beam # 2. Become. Therefore, the delay profile is disturbed, and the communication quality is degraded.

Therefore, in a conventional mobile communication system using multi-beam transmission, an interference wave from a beam other than a desired beam is received, and there is a problem that communication quality is greatly deteriorated.

[0005]

SUMMARY OF THE INVENTION The present invention seeks to accommodate a large number of mobile stations in a base station having a multi-beam pattern, especially with a small number of channels for a downlink (base station transmission, mobile station reception) large capacity transmission path. Things.

[0006]

According to a first aspect of the present invention, there is provided a radio station having an antenna and a transmitting / receiving means and a plurality of radio stations having an antenna and a transmitting / receiving means. In a mobile communication system that performs mutual communication with the wireless stations A and B, the wireless station A
.., #K,..., #N (N is an integer of 2 or more) to form a multi-beam pattern in which different known pilot signals P1,..., PK,. Having means,
The communication radio station B receives a multi-beam to which a pilot signal is allocated, and has a delay profile measuring unit for measuring each delay profile for each pilot signal, and a delay profile memory for storing each delay profile. Means for transmitting information to a plurality of wireless stations B by using different beams (hereinafter referred to as “information beams”) optimal for each wireless station B on the same channel; When the beam is received and the received signal delay profile is measured by the delay profile measuring unit, and the optimal beam for the communication radio station B is #K, the reception signal delay profile of the information beam received by the communication radio station B is #K stored in the delay profile memory
And a calculation processing unit for performing a calculation process of dividing by a stored delay profile for other interference beams and outputting the result.

According to a second aspect of the present invention, in the mobile communication system according to the first aspect, the antenna of the communication radio station B has a substantially non-directional radiation pattern when receiving a multi-beam to which a pilot signal is assigned, and the information beam At the time of reception, there is provided a radiation pattern changing means for estimating a desired wave direction and an interference wave direction, and as a radiation pattern for maximizing a power ratio between the desired wave and the interference wave. Based on the radiation pattern that maximizes the power ratio between the wave direction and the interference wave direction, calculate the radiation pattern levels WD and WUm (m = 1, ..., MM: number of interference waves) in the desired wave and the interference wave direction based on the radiation pattern The arithmetic processing unit is configured to store a #K storage profile stored in a delay profile memory for a received signal delay profile received by the communication wireless station B. The multiplied by WD multiplied by the multiplier, whereas, and outputs performs arithmetic processing dividing by WUm multiplied respectively multiplier profile stored for the beam to be other interferences.

According to a third aspect of the present invention, there is provided a radio station A having an antenna and transmission / reception means, and a plurality of radio stations B having an antenna and transmission / reception means. In the mobile communication system performed, the wireless station A
Known pilot signals P1,..., PK,... Different for beams # 1,..., #K,.
.. Having a means for forming a multi-beam pattern to which a PN is assigned, wherein the communication radio station B receives the multi-beam to which the pilot signal is assigned, and measures a delay profile for each pilot signal. And a delay profile memory for storing the respective delay profiles. The wireless station A transmits information to a plurality of wireless stations B on the same channel using different beams optimal for each wireless station B (hereinafter referred to as “information The communication radio station B receives the information beam, measures the received signal delay profile in the profile measurement unit, and assigns the beam optimal for the communication radio station B to #K. when doing,
A time filter that passes the measured received signal delay profile of the information received by the communication radio station B, and sets the time filter to a predetermined level of the delay profile of the beam #K stored in the delay profile memory A time filter that passes a certain time range of the above signal part, or a time filter that does not pass a certain time range of a signal part whose level is equal to or higher than a preset level from a stored profile of a beam other than #K of large interference, or It is characterized by comprising a time filter combining both time filters.

According to a fourth aspect of the present invention, there is provided the mobile communication system according to any one of the first to third aspects, further comprising a time-domain / frequency-domain conversion unit for converting a time-domain signal into a frequency-domain signal. In this case, a frequency filter is used in place of the arithmetic processing of the arithmetic processing unit or the time filter.

[0010]

(Embodiment 1) FIG. 1 is a schematic explanatory view of Embodiment 1 of the present invention. The base station 2 forms a multi-beam pattern 1 carrying different information at the same frequency, selects an optimal beam for each mobile station (only the mobile station 3 is shown in the figure), and performs mutual communication. As shown in FIG. 1, in the communication between the base station 2 and the mobile station 3, 4 is an optimal propagation path, here, a direct wave from the beam # 3, 5 is a building reflection arriving from a beam other than the optimal beam. Here, the case of a reflected wave from the beam # 2 is shown, and 6 and 5 are similarly interference waves. In this case, in the mobile station, the interference waves 5, 6
Can be removed.

The operation principle will be described below. FIG. 2 is a conceptual diagram of the first embodiment of the present invention, and FIG. 3 is a block diagram of a mobile station according to the first embodiment of the present invention. First, as shown in FIG. 2, different pilot signals P1,..., PK,.
・ ・, PN is assigned. Each pilot signal is fixed in the system and is also known by the mobile station (in advance,
Register with the mobile station). Further, it is desirable that each pilot signal is orthogonal.

At the mobile station, all signals are received by the antenna 31. The received signal is converted by a frequency converter / low noise amplifier (D
C (Down Converter) / LNA (Low Noise Amp)) 32 converts the frequency and amplifies it.
Demodulated. Basically, it is desirable that the mobile station is an omnidirectional antenna, but it is not always an omnidirectional antenna. In such a state, the received signal is correlated with each pilot signal in the delay profile measuring section 34, so that the delay profile for each pilot signal can be measured. FIG. 4 shows delay profiles received by the mobile station arranged in descending order of the maximum path power. These delay profiles are stored in the delay profile memory 35 of the mobile station.

In FIG. 4, the radio wave from # 3 is the strongest, and transmission using this beam is considered to provide the highest transmission quality. At this stage, the mobile station transmits this information to the base station, and the base station and the mobile station are communicating using the # 3 beam. Alternatively, the base station comprehensively determines the information of all the mobile stations that are trying to communicate and determines a beam to communicate with each mobile station. At this time, in order to accommodate the most mobile stations with a small number of channels, it is necessary to increase the number that can communicate with a plurality of mobile stations on the same channel. In this case, if a base station having a multi-beam antenna can accommodate one mobile station in each beam using the same channel for each beam, it can communicate with a mobile station several times the number of beams and can accommodate the capacity. Goes up.

As shown in FIG. 5 (a), if a beam of # 3 is assigned to this mobile station 3, beams other than # 3 are reflected and incident on the mobile station 3, so that these beams have large interference. Becomes FIG. 5B shows the received signal delay profile and the processing method in this case. The received profile is already measured by the pilot signal, and the arithmetic processing unit 36 performs arithmetic processing with the stored delay profile for each beam stored in the delay profile memory 35. As shown in FIG. 5 (b), the calculation is to multiply the received signal delay profile by the stored delay profile of beam # 3 for the stored delay profile of beam # 3 transmitting its own desired information, For the storage delay profiles of beams # 2 and # 4 transmitting other signals:
Divide by the received signal delay profile and the storage delay profile of beams # 2 and # 4. At this time, the number and the number of the storage delay profile of the beam considered as an interference wave are determined based on conditions such as the required quality of the system and whether the simultaneous channel is transmitted from the beam. It is not necessary to divide by all the storage delay profiles other than the storage delay profile of the desired beam. By these arithmetic processings, signals that cause interference are removed.

This principle can be explained as follows. By adopting a multi-beam antenna for the base station antenna,
Radio waves transmitted from each beam fly in different directions.
For this reason, the arrival path of the radio wave to the mobile station slightly differs depending on the emitted beam. Therefore, the arriving radio waves have slightly different arrival times due to differences in routes. Therefore, interference is separated using the difference in arrival times. In particular, in future mobile communication, it is certain that the frequency band of the system will be further widened in order to perform high-speed transmission, thereby improving the time resolution capability, so that this method is very effective. The major difference from the equalizer is the slight training (pilot signal transmission)
Since the arrival time of the interference wave and the desired wave is different, convergence is fast,
Not only is the desired wave quality improved, but also the interference wave can be independently suppressed.

(Embodiment 2) FIG. 6 is an explanatory diagram of Embodiment 2 of the present invention, and FIG. 7 is a block diagram of a mobile station according to Embodiment 2 of the present invention. In this case, a multi-beam antenna is used for the base station, and an adaptive antenna capable of forming an arbitrary pattern is used for the mobile station. Here, each number is the same as in the first embodiment. In this case, the procedure from receiving each beam pilot signal to generating a storage delay profile is the same. The radiation pattern of the mobile station at this time is operated as a pattern close to omnidirectional as an initial pattern. Then, after a beam for communication is allocated from the base station,
The adaptive operation is started by the adaptive antenna 311 of the mobile station. This adaptive operation uses array antennas 1,..., J (J: number of antennas) having variable complex weight multipliers 314, and outputs complex weights U1,. After adjusting the amplitude and phase by multiplying by UJ, adder 315 adds the amplitude and phase to obtain an output. By appropriately determining the complex weight according to the radio wave environment, it is possible to control the directivity null and the main beam.

Generally, by performing an adaptive operation, as shown in FIG. 6B, an operation is performed so as to direct the peak of the radiation pattern in the desired wave direction and null in the interference wave direction. After that, the calculation procedure of the delay profile is performed. At this time, the radiation pattern is already different from the radiation pattern of the mobile station when each beam pilot signal is received and the stored delay profile is generated. Therefore, as shown in FIG. 6B, the levels W3 and W2 of the radiation pattern of the desired wave and the interference wave based on the complex weight U of the desired wave and the interference wave direction pattern after the adaptive operation are performed. ,
W4 (here, W3 + W2 + W4 = 1) is calculated by the radiation pattern level calculation unit 316, and the value is multiplied by each of the storage delay profiles # 3, # 2, and # 4 by a multiplier, and then is calculated with the reception signal delay profile The processing is performed by the arithmetic processing unit 36. By this operation, the interference wave is further suppressed as compared with the case of only the adaptive operation, and the communication quality is improved. Particularly, in a mobile station, there may be cases where nulls cannot be completely formed in the interference wave direction because too many antennas cannot be installed. In this case, by using this method together, the communication quality can be greatly improved. (Embodiment 3) FIG. 8 is an explanatory diagram of Embodiment 3 of the present invention, and FIG. 9 is a block diagram of a mobile station according to Embodiment 3.

This embodiment is a method of passing through a time filter without performing an operation between delay profiles. here,
7 is a filter passage time, 8 is a filter passage inhibition time, 9
Is a preset threshold level. This embodiment is the same as the above-described embodiment until the storage delay profile is formed. Therefore, FIG. 8 shows only a part that replaces the arithmetic processing of the above-described embodiment. As shown in FIG. 8, since the delay profile of the radio wave emitted from each beam is known, a time filter is formed by the time filter generation unit 37 from the delay profile.

As shown in FIG. 8 (a), for a desired beam, a portion where the delayed wave is present is defined as a filter passing time, and a portion without the delayed wave is defined as a passing blocking time. The portion having the delayed wave is a signal portion having a level higher than the threshold level. By passing the received signal delay profile through this filter, only the desired signal is extracted. Therefore, the interference signal portion is removed from the desired beam # 3, and the desired signal is extracted. on the other hand,
As shown in FIG. 8 (b), with respect to the interference beam, a portion where the delayed wave is present is defined as a filter passage blocking time, and a portion without the delayed wave is defined as a filter passage time. By passing the reception information delay profile through this filter, only the interference signal is suppressed. Therefore, an interference signal having a large level of the interference beams # 2 and # 4 is removed. Further, the filters may be arranged in series or in parallel in multiple stages, for example, after passing the received signal delay profile through a desired beam filter, passing through some interference beam filters, or combining through both.

In this case, the passing time and the blocking time of each filter are mainly determined by the setting of the threshold level. The level setting is also determined by the system so as to obtain appropriate communication quality. In addition, the passing time and the blocking time of each filter may be determined by factors other than the threshold level depending on the system based on the position of the delayed wave. (Embodiment 4) FIG. 10 is a block diagram showing Embodiment 4 of the present invention. Here, as the configuration of the mobile station, a case where processing is performed on the frequency axis using time domain / frequency domain conversion such as Fourier transform or cosine transform is shown. Here, 31 is an antenna.

FIG. 10A corresponds to the first and second embodiments and shows the configuration of a mobile station embodying the basic method.
Each block shares the functions already described. However, as an output, the signal is converted into a signal in the frequency axis direction by the Fourier transform unit 39 and output. FIG. 10B also corresponds to the first and second embodiments, and the delay profile measuring unit 34
The Fourier transform unit 40 converts the delay profile measured in Step 4 into a frequency axis and stores it in the delay profile memory 35, and the arithmetic processing unit 36 also performs an arithmetic operation on the frequency axis. FIG. 10C corresponds to the first to third embodiments. In the first and second embodiments, the operation coefficient calculating unit 42 based on the storage delay profile memory of the delay profile memory 35 is used.
Is converted from a time function to a frequency function, or a time filter generation unit in the third embodiment.
At 42, the time filter generated from the delay profile is converted to the frequency axis, and is input to the frequency filter generator 43. Thereby, when a pilot signal is received, it is necessary to measure a delay profile, but if a frequency function or a time filter is converted to the frequency axis, the received information data is not processed at all, and the frequency function is directly multiplied, or Only the processing of the frequency filter generation unit 43 that passes the frequency filter is required.

In the above embodiment, an example has been described in which a base station forms a multi-beam pattern and performs mutual communication with a mobile station. However, the mobile station forms a multi-beam pattern and performs communication with a plurality of base stations. It can also be configured to perform

[0023]

Since the mobile communication system of the present invention is configured as described above, it is possible to spatially separate the transmission path with a small amount of information from the mobile station. , A mobile communication system capable of accommodating many mobile stations with a small number of channels can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram of a first embodiment.

FIG. 2 is a conceptual diagram of the first embodiment.

FIG. 3 is a block diagram of a mobile station according to the first embodiment.

FIG. 4 is a diagram showing an example of a storage delay profile.

FIG. 5 is a diagram for explaining the calculation processing according to the first embodiment.

FIG. 6 is a diagram for explaining the calculation processing according to the second embodiment.

FIG. 7 is a block diagram of a mobile station according to a second embodiment.

FIG. 8 is a diagram for explaining a time filter according to a third embodiment.

FIG. 9 is a block diagram of a mobile station according to a third embodiment.

FIG. 10 is a block diagram of a mobile station according to a fourth embodiment.

FIG. 11 is a diagram illustrating a conventional example.

[Explanation of symbols]

 Reference Signs List 1 base station 2 mobile station 31 antenna 32 frequency converter / low noise amplifier 33 detector / demodulator 34 delay profile measuring unit 35 delay profile memory 36 operation processing unit 37 time filter generation unit 39,40,41 Fourier transform unit 42 operation Count calculation unit / time filter generation unit 43 Frequency filter generation unit 311 Adaptive antenna

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04M 1/725 H04M 1/74 5K067 1/74 3/18 3/18 H04B 7/26 BF term (reference ) 5K022 FF00 5K027 AA11 BB03 BB04 CC08 EE11 GG08 5K051 AA02 BB01 CC07 DD15 EE01 EE05 EE06 FF01 FF11 HH17 HH26 5K052 AA01 BB08 CC06 DD03 EE17 FF31 GG11 GG20 5K0A03 A03 BB04 A03

Claims (4)

[Claims] 1. A radio station A having an antenna and transmission / reception means
And a plurality of wireless stations B each having an antenna and a transmitting / receiving means, and performing a mutual communication between the wireless stations A and B. In the mobile communication system, the wireless station A includes beams # 1,. K,..., #N (N is an integer of 2 or more) different known pilot signals P1,
.., PK,..., PN assigned means for forming a multi-beam pattern, the communication radio station B receives the multi-beam assigned the pilot signal, and sets each delay profile for each pilot signal. And a delay profile memory for storing the respective delay profiles. The radio station A transmits information to a plurality of radio stations B on the same channel for each radio station B. Another beam (hereafter,
The communication radio station B receives the information beam, measures the received signal delay profile by the delay profile measurement unit, and determines the optimum beam for the communication radio station #K. Then, the received signal delay profile of the information beam received by the communication radio station B is multiplied by the delay profile of #K stored in the delay profile memory, and the delay corresponding to the other interference beam is multiplied. A mobile communication system comprising: an arithmetic processing unit that performs arithmetic processing of dividing by a profile and outputs the result. 2. The mobile communication system according to claim 1, wherein the antenna of the communication radio station B has an almost non-directional radiation pattern when receiving a multi-beam to which a pilot signal is assigned, and a desired wave when receiving an information beam. The communication radio station B estimates a direction and an interference wave direction, and has a radiation pattern changing unit that sets a radiation pattern that maximizes a power ratio between the desired wave and the interference wave. The radiation pattern level WD that maximizes the power ratio of the desired wave and the interference wave based on the radiation pattern that maximizes the power ratio,
WUm (m = 1,..., MM: the number of interference waves) has a radiation pattern level calculation means, the arithmetic processing unit, for the received signal delay profile received by the communication wireless station B, the delay profile The multiplier multiplies the storage delay profile of #K stored in the memory by WD times with a multiplier, and multiplies the storage profiles for other beams that cause interference by WUm with the multiplier, and outputs the result. A mobile communication system, comprising: 3. A radio station A having an antenna and a transmission / reception means.
And a plurality of wireless stations B each having an antenna and a transmitting / receiving means, and performing a mutual communication between the wireless stations A and B. In the mobile communication system, the wireless station A includes beams # 1,. K,..., #N (N is an integer of 2 or more) different known pilot signals P1,
.., PK,..., PN assigned means for forming a multi-beam pattern, the communication radio station B receives the multi-beam assigned the pilot signal, and sets each delay profile for each pilot signal. And a delay profile memory for storing the respective delay profiles. The radio station A transmits information to a plurality of radio stations B on the same channel for each radio station B. Beam (hereinafter,
The communication radio station B receives the information beam, measures a received signal delay profile in the profile measurement unit, and generates an optimal beam for the communication radio station #. When K, communication radio station B
A time filter that passes the measured received signal delay profile of the information received at the signal section of a predetermined level or more of the delay profile of the beam #K stored in the delay profile memory. A time filter that passes through a time range with
Alternatively, it is possible to configure a time filter that does not pass through a certain time range of a signal portion of a stored delay profile of a beam other than the large #K of interference having a signal level or higher, or a time filter that combines the two time filters. Characteristic mobile communication system. 4. The mobile communication system according to claim 1, further comprising a time-domain / frequency-domain conversion unit, wherein a signal in a time domain is converted into a signal in a frequency domain, and the arithmetic processing unit is provided. A mobile communication system characterized by using a frequency filter instead of the time filter.