JP3400310B2 - Mobile communication channel configuration method and mobile communication system - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a radio used for communication between a radio base station and a mobile station in a mobile communication system composed of a plurality of radio base stations and a plurality of mobile stations communicating with the radio base stations. The present invention relates to a channel configuration method for mobile communication that configures a channel and a mobile communication system.

[0002]

2. Description of the Related Art In mobile communication systems such as mobile phones and car phones, which are widely used at present, the entire service area is divided into relatively small radio zones called cells to provide services. Such a system is called a cellular system. Such a system, as shown in FIG.
A plurality of wireless base stations 1 that cover the divided wireless zones
11 and a plurality of mobile stations 112 that communicate with each other by setting a wireless channel.

In a mobile communication system, voice signals and data are transmitted between a radio base station and a mobile station via a radio channel. Radio transmission in a mobile communication system has a problem that the propagation loss fluctuates greatly due to the movement of the mobile station, and the reliability of the transmission is significantly deteriorated in the portion where the reception level drops significantly. Various techniques such as error correction technique and retransmission control have been devised and put into practical use as techniques for solving such problems and performing highly reliable transmission. A technique for improving transmission reliability such as radio wave propagation and error correction in mobile communication is described in detail in, for example, “Mobile Communication” edited by Masaaki Shinji (Maruzen, 1989), and therefore the description thereof is omitted here. To do.

As described above, as one of the techniques for improving the reliability of radio transmission in mobile communication and enabling high quality transmission and large capacity, a known signal pattern is transmitted from a transmission source as a pilot signal, On the receiving side, there is a technique of demodulating an information signal with high reliability by using the demodulation result of this pilot signal. By using the pilot signal, it is possible to synchronize with the received signal with high accuracy,
Furthermore, because the characteristics of the propagation path between the transmission point and the reception point can be estimated with high accuracy, it is possible to increase the reliability of transmission or provide the same quality service with the same frequency bandwidth. If this is done, there is an advantage that a larger capacity system can be constructed.

By the way, in a system such as a public mobile communication system in which a large number of mobile stations share a radio base station, a method for constructing a channel for supplying a pilot signal (hereinafter referred to as a pilot channel) is used. There are two main types. One is a method of commonly supplying a pilot channel to a plurality of mobile stations, and the other is a method of individually supplying a pilot channel to a plurality of mobile stations. The latter method of using individual pilot channels is further classified into two. That is, it is classified into a method of configuring a pilot channel using a frequency channel or spreading code different from the communication channel and a method of configuring a pilot channel by time division multiplexing using the same frequency channel or spreading code as the communication channel. It

FIG. 7, FIG. 8 and FIG. 9 schematically show these channel construction methods. 7 is a method of using a common pilot channel for a plurality of mobile stations, FIG. 8 is a method of using a separate pilot channel for each mobile station by using a channel different from the communication channel, and FIG. 9 is the same as the communication channel. 2 shows a method of using an individual pilot channel for each mobile station by time division in the above channel. Comparing the characteristics of the common pilot channel and the dedicated pilot channel, basically, the common pilot channel is characterized by higher synchronization accuracy and larger capacity because it does not use useless radio resources.

As described above, in order to realize a large capacity and high efficiency system in a mobile communication system, not only the wireless transmission technology described so far, but also various more advanced technologies peculiar to the cellular system are required. Become. One of such techniques is application of an adaptive array antenna to a base station. The adaptive array antenna is a technique for adaptively controlling the directivity of antennas by adaptively combining signals from a plurality of antennas by a digital signal processing technique. When the adaptive array antenna is used, it is possible to control the directivity so that, for example, the gain is high in the desired wave direction and the gain is low in the mobile station direction that emits the interference wave. As a result, the desired wave can be received with the maximum intensity while suppressing the interference interference from the interfering station to an extremely small level, and it is possible to provide a mobile communication system of high quality and large capacity.

FIG. 10 is a diagram for explaining interference avoidance using an adaptive array antenna. When two mobile stations exist, the antenna directivity is adaptively controlled for each mobile station. , Schematically showing how to avoid mutual interference. In the figure, when two stations, mobile station A and mobile station B, exist in the radio zone covered by one base station, transmission to mobile station A is performed with the directivity shown by the solid line, and Direction strongly, mobile station B
To transmit weakly to reduce interference. Similarly, by using the directivity shown by the broken line for the transmission to the mobile station B, the interference is reduced because the transmission is strong in the direction of the mobile station B and weak in the direction of the mobile station A. In the figure, for example, a code division multiple access (CD)
Although an example in the case of a system in which a plurality of mobile stations share the same frequency channel like the (MA) method is shown, other frequency division multiple access (Frequency Division Multiple Access)
s; FDMA) method and time division multiple access (Time Division M
Also in the ultimate access (TDMA) system, interference from the same frequency channel repeatedly used geographically can be avoided, and the same effect can be obtained. Regarding the adaptive array antenna, for example, Mizuno, Ohbell, "Application of Adaptive Array Antenna to Communication" (IEICE Transactions B-II, Vol.J75-B-II, No.11, pp.733-741, 1992
In November), an application example and effects of the adaptive array antenna to mobile communication are explained.

On the other hand, in recent years, in various communication systems including mobile communication, the demands of users have been diversified or the development of transmission technology has made it necessary to flexibly use various transmission rates for each communication. . For example, ISDN (Integrated Services Digital) that handles various services in an integrated manner.
Network) provides a higher transmission rate of 128 kbit / s, 384 kbit / s, etc. based on the transmission rate of 64 kbit / s. In mobile communication, for example, in the PDC (Personal Digital Cellular) method, which is a digital mobile communication service in Japan, in addition to voice communication, data communication of 9600 bps and maximum 2
The speed / diversification of the transmission speed is progressing, such as the application of packet communication capable of 8.8 kbps communication. PDC
For the method, refer to "Digital Car Telephone System Standard RCR STD-27" by the Association of Radio Industries and Businesses.
Since there is detailed explanation in “F” and the like, the explanation is omitted here. In the next-generation mobile communication system, the transmission speed is further increased and it is required to provide services at various transmission speeds, and a system that can efficiently transmit services at various transmission speeds will be constructed. That has become a very important issue.

By the way, generally, the higher the information transmission rate, the more radio resources such as frequency channels and transmission power are required. For this reason, it has been pointed out that when a service having a high transmission rate and a service having a low transmission rate are mixed, the capacity is reduced and the efficiency is reduced. Furthermore, this problem becomes even more important due to the limited frequency band available in mobile communications. In such a mobile communication system, in order to efficiently provide various services, it is extremely important to apply the technique unique to the above-described cellular system, particularly the adaptive array antenna to the radio base station. Since it is possible to reduce interference between communications using the same frequency channel, it is considered to be effective in increasing capacity or efficiently providing high-speed transmission service.

[0011]

However, when an interference canceling method such as an adaptive array antenna is applied to a mobile communication system that communicates between a radio base station and a mobile station by using a communication channel and a pilot channel together. However, there are the following serious disadvantages that are not preferable for practical use. In other words, the adaptive array antenna controls the directivity so that the gain of the antenna with respect to the interference wave becomes small, and the signals to be transmitted to a plurality of mobile stations that are communicating at the same time are transmitted so that they do not overlap with each other. . Therefore, there is a drawback in that it is impossible in principle to use a common pilot channel that is excellent in terms of capacity and synchronization accuracy. On the contrary, if the dedicated pilot channel is used, it is possible to supply the pilot signal to each mobile station, but there is a drawback that the device configuration becomes complicated or wasteful power is required and the capacity is reduced.

Further, in removing interference by the adaptive array antenna, it is necessary to have the same number of antennas as the number of interfering mobile stations to be removed (the number of interfering mobile stations to be removed + 1). When applied to an actual mobile communication system in which one radio base station is shared by mobile stations, there is a serious disadvantage that the base station equipment becomes very complicated and expensive, which is not preferable in practical use.

The present invention has been made in view of the above,
It is an object of the present invention to provide a mobile communication channel configuration method and a mobile communication system that enable the construction of a high quality and large capacity mobile communication system and the efficient provision of various services.

[0014]

[0015]

[0016]

In order to solve the problem] was to achieve the above purpose
Therefore, the present invention according to claim 1 is a channel configuration method in a mobile communication system including a plurality of radio base stations and a mobile station that communicates with the radio base stations, wherein high-speed communication is performed in each communication channel. Correspondingly, the channel in which the directivity of the base station antenna is controlled individually is used, and the channel in which the directivity of the base station antenna is commonly controlled for a plurality of communication channels is used for low-speed communication. User data and common pilot signal and low-speed communication user data are canceled by phase change.
The gist is to give the directivity of the tenor and then combine each antenna.

According to the first aspect of the present invention, the high speed communication uses a channel in which the directivity of the base station antenna is individually controlled corresponding to each communication channel, and the low speed communication uses a plurality of communication channels. Since the channel in which the directivity of the base station antenna is controlled is commonly used, interference between high-speed communication and low-speed communication, and also interference between high-speed communication can be avoided, and a high-quality and large-capacity mobile communication system is provided. be able to.

Further, according to the present invention in a second aspect, the mobile communication constituted by the mobile station communicating with combined communication channels set multiple pilot channels and the dedicated radio base station and the radio base station System,
High-speed communication channels use individual pilot channels corresponding to each communication channel, low-speed communication channels use common pilot channels commonly used by multiple communication channels, and high-speed communication uses individual pilot channels corresponding to each communication channel. A channel in which the directivity of the base station antenna is controlled is used, and a channel in which the directivity of the base station antenna is controlled is commonly used for a plurality of communication channels for low-speed communication,
Individual pilot signals and high-speed user data,
The gist is to synthesize the common pilot signal and the low-speed communication user data for each antenna after giving the antenna directivity by changing the phase .

According to the second aspect of the present invention, the high-speed communication channel uses an individual pilot channel corresponding to each communication channel, and the low-speed communication channel uses a common pilot channel commonly used by a plurality of communication channels. For high speed communication, a channel in which the directivity of the base station antenna is individually controlled corresponding to each communication channel is used, and in low speed communication, the directivity of the base station antenna is commonly controlled for a plurality of communication channels. To use
A mobile communication system having a large capacity and high quality can be provided.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram for explaining a channel configuration method for mobile communication according to an embodiment of the present invention.
The figure shows the case where the wireless base station and the three mobile stations A, B, and C communicate with each other. In this example, mobile stations A and B perform low-speed transmission, and mobile station C performs high-speed transmission. There is no separate pilot channel for low-speed transmission of mobile stations A and B, but a common pilot channel is used. On the other hand, the mobile station C that performs high-speed transmission uses a dedicated pilot channel. In addition,
In the figure, an example of a case where a common pilot channel is configured by time division multiplexing is shown, but this does not limit the embodiment of the present invention, and it goes without saying that separate frequency channels or spreading codes are used for individual The pilot channel may be configured.

FIG. 2 is a block diagram showing the configuration of the radio base station shown in FIG. In the radio base station shown in FIG.
Common pilot channel modulation circuit 21 for spread-modulating a common pilot signal, low-speed communication modulation circuits 23a to 23n for spread-modulating low-speed communication user data using a common pilot, high-speed communication pilot using an individual pilot channel The outputs from the high-speed communication modulation circuits 25a to 25n for spread-modulating signals and user data are combined by a combiner 27, power-amplified by a high-frequency power amplifier 29 thereafter, and radiated from an antenna 31. The common pilot channel modulation circuit 21 uses a fixed value or a fixed pattern as the data to be modulated, and is spread-modulated by the spread modulator 35 by the spread code commonly used by the low-speed communication users from the spread code generator 33. In the modulation circuits for low-speed communication 23a to 23n, the data from the low-speed communication user is subjected to conversion such as error correction coding and bit interleaving by the encoder 37, and is further subjected to individual spreading codes from the spreading code generator 39. Spread modulation is performed by the spread modulator 41. In the high speed communication modulation circuits 25a to 25n, the data from the high speed user is
After the encoder 43 performs conversion such as error correction coding and bit interleaving, the pilot signal and the multiplexer 45
And is spread-modulated by a spread modulator 49 by an individual spread code from a spread code generator 47 for each circuit.

FIG. 2 shows the case where the individual pilot channels used in the high speed communication are multiplexed by time division. However, in the case where the individual pilots are formed by using the channel composed of another spreading code, the high speed communication is performed. As the diffusion modulation circuit for use, ones such as 51a to 51n in FIG. 3 may be used. That is, each of the spreading modulation circuits 51a to 51n is provided with spreading code generators 53 and 55 corresponding to the user data and the pilot signal, respectively, and the user data and the pilot signal are spread channels 57 as separate channels.
And 59 are spread-modulated. Of course, no matter which of the time division multiplexing shown in FIG. 2 and the multiplexing using another channel shown in FIG. 3 is used, the application effect of the present invention does not change, and the same effect can be obtained.

Next, a channel configuration method related to control of antenna directivity will be described. FIG. 4 is a block diagram showing the configuration of a radio base station to which the channel configuration method of the present invention is applied. In the figure, low-speed communication modulation circuits 61a to 61 for spreading and modulating low-speed communication user data.
It shows a case where N pieces of n and two pieces of high-speed communication modulation circuits 63 and 65 for performing spread modulation of high-speed communication user data are mounted. In addition, the figure shows a case where the signals are transmitted from the three antennas 87 to 89. For low speed communication, a plurality of low speed communication modulation circuits 6
The outputs from 1a to 61n are combined by the combiner 67, then power-amplified by the high-frequency power amplifier 69, and the phase is changed by the phase shifters 75 to 77 corresponding to the three antennas 87 to 89 to be transmitted. After making it synthesizer 84 ~
86 and antennas 87-89. For high speed communication, the power is individually amplified by the high frequency power amplifiers 71 and 73, and the phase is changed by the phase shifters 78 to 83 corresponding to the three antennas 87 to 89 individually provided in the modulation circuits 63 and 65 for high speed communication. Then synthesizer 84
~ 86 and antennas 87-89.

In FIG. 4, the power is amplified by the power amplifiers 69 to 73, and then the phase is changed by the phase shifter. However, such a configuration is not adopted, but the high frequency power amplifier corresponding to each antenna is used. It is also possible to adopt a configuration in which the power amplification is performed after combining the signals after changing the phase from each circuit using, that is, immediately before radiating from the antenna. The directivity of the antenna is determined by the phase change provided by the phase shifter, and the most characteristic feature of the present invention is that the same directivity is obtained by using a common phase shifter for a plurality of modulation circuits for low speed communication. The characteristic is that each modulation circuit for high-speed communication has a separate directivity by using a phase shifter for each.

FIG. 5 is a block diagram showing the configuration of a radio base station according to another embodiment of the present invention. The wireless base station shown in FIG. 4 has a plurality of low-speed communication modulation circuits 61a ...
4 is different from FIG. 4 in that when the output from 61n is combined, the common pilot signal from the common pilot channel modulation circuit 90 is also combined by the combiner 67, and other parts are the same as FIG. Is.

Although the present embodiment has been described on the premise of the code division multiple access (CDMA) system, this does not limit the present invention. In addition to CDMA, there are a frequency division multiple access (FDMA) system and a time division multiple access (TDMA) system as a method of multiple access, and any of them can be applied and the same effect can be obtained.

[0028]

As described above, according to the present invention,
High-speed communication channels use individual pilot channels corresponding to each communication channel, and low-speed communication channels use common pilot channels that are commonly used by multiple communication channels. Even when the method is applied, the dedicated pilot channel is used for high-speed communication, so it is possible to configure so as to avoid interference between high-speed communication and low-speed communication. It becomes possible to provide a communication system. Since the common pilot channel, which is advantageous in terms of capacity and synchronization accuracy, can be used for low-speed communication, it is possible to provide a mobile communication system of high quality and large capacity.

Further, according to the present invention, the high speed communication uses a channel in which the directivity of the base station antenna is individually controlled corresponding to each communication channel, and the low speed communication uses a common base station for a plurality of communication channels. Since the channel in which the directivity of the antenna is controlled is used, it is possible to avoid interference between high-speed communication and low-speed communication as well as interference between high-speed communication,
On the other hand, since the common directivity pattern is used for low speed communication, the system does not become complicated, and it is possible to provide a high quality and large capacity mobile communication system. Further, the transmission power required for high-speed communication can be suppressed to a low level, and even a mobile station that can only have a small transmission power can enjoy the high-speed transmission service.

Further, according to the present invention, the high speed communication channel uses the individual pilot channel corresponding to each communication channel, the low speed communication channel uses the common pilot channel commonly used by a plurality of communication channels, and the higher speed communication is performed. Controls the directivity of the base station antennas individually for each communication channel, and controls the directivity of the base station antennas for multiple communication channels in low-speed communication. A communication system can be provided.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a channel configuration method for mobile communication according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a radio base station to which the channel configuration method of the embodiment shown in FIG. 1 is applied.

FIG. 3 is a block diagram showing another configuration of a modulation circuit for high speed communication used in the radio base station shown in FIG.

FIG. 4 is a block diagram showing a configuration of a radio base station to which a channel setting method according to another embodiment of the present invention is applied.

FIG. 5 is a block diagram showing a configuration of a radio base station to which a channel setting method according to another embodiment of the present invention is applied.

FIG. 6 is a diagram showing a configuration of a mobile communication system to which the present invention is applied.

FIG. 7 is a schematic diagram showing a case where a common pilot channel is used for a plurality of mobile stations.

FIG. 8 is a schematic diagram showing a case where an individual pilot channel is used for each mobile station by using a channel different from a communication channel.

FIG. 9 is a schematic diagram showing a method of individually using a pilot channel for each mobile station by time division on the same channel as a communication channel.

FIG. 10 is a schematic diagram illustrating interference avoidance using an adaptive array antenna.

[Explanation of symbols]

21 common pilot channel modulation circuit 23a-23n low speed communication modulation circuit using individual pilot channel 25a-25n high speed communication modulation circuit using individual pilot channel 27 combiner 29 high frequency power amplifier 33, 39, 47 spreading code generator 35 , 41, 49 Spread modulator 37, 43 Encoder 45 Multiplexer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI H04Q 7/30 (72) Inventor Kouji Ohno 2-10-1 Toranomon, Minato-ku, Tokyo NTT Network Communications Network Co., Ltd. (72) Inventor Seizo Onoe 2-10-1 Toranomon, Minato-ku, Tokyo NTT Mobile Communication Network Co., Ltd. 267 SK-Telecom Company Limited (72) Inventor Junmogu Seoul Jung Namdaemunro 5-South Korea 267 SK-Telecom Company Limited (72) Inventor Byung Gim South Korea Seoul Jung-Dammun 5-Ka Telecom 267 Company Limited (56) References JP-A-8-274734 (JP, A) JP-A-9-162758 (JP, A) JP-A-9-8770 (JP, A) JP-A-8-505494 (JP, A) 58) Fields surveyed (Int.Cl. ⁷ , DB name) H04B ^7/ 24-7/26 H04Q ⁷ /00-7/36

Claims (2)

(57) [Claims] 1. A channel configuration method in a mobile communication system comprising a plurality of radio base stations and a mobile station communicating with the radio base stations, wherein high-speed communication is performed individually for each communication channel. The channel with the directivity of the station antenna is used, and the channel with the directivity of the base station antenna is commonly used for multiple communication channels for low-speed communication. Individual pilot signals and user data for high-speed communication, and the common pilot are used. a user data signal and the low-speed communication by the phase change
A channel configuration method for mobile communication, which comprises synthesizing each antenna after giving directivity of the antenna. 2. A mobile communication system comprising a plurality of radio base stations and a mobile station that communicates with the radio base stations using a pilot channel and a communication channel set individually, wherein a high-speed communication channel is Individual pilot channels corresponding to each communication channel are used, low-speed communication channels use a common pilot channel commonly used by multiple communication channels, and high-speed communication uses individual base station antennas corresponding to each communication channel. Using a channel whose directivity is controlled, low-speed communication uses a channel in which the directivity of the base station antenna is controlled commonly to a plurality of communication channels, an individual pilot signal and user data of high-speed communication,
A mobile communication system, characterized in that a common pilot signal and user data for low-speed communication are combined for each antenna after giving directivity of the antenna by phase change .