JP3497695B2 - Wireless communication system and code channel processing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a code division multiple access (CDMA) wireless communication system.

[0002]

2. Description of the Related Art A code division multiple access (CDMA) system is adopted as one system of a mobile communication system capable of increasing user capacity and improving communication quality. In this CDMA system, a specific code is assigned to each line and a modulated wave of the same carrier frequency is spread and transmitted by this code, while the receiving side synchronizes the codes to identify a desired line. A connection method, SSMA (SpreadSpectrum Multiple Access)
) Also called method. The CDMA system has the advantage that it does not require an initial connection process and can communicate directly for each call as long as the codes are determined for each other, and that it has excellent confidentiality and interference resistance. .

In a communication system employing this CDMA system, a plurality of base stations whose service areas are within a predetermined distance range in which wireless communication is possible are arranged so that the service areas partially overlap with the service areas of adjacent base stations. Control operations such that the mobile terminals in the service area provide communication services with the base station, and when moving to the adjacent service area, the communication service baton-touches to the destination base station. By doing so, the communication service for the mobile terminal can be continued. The service area of each base station in such a system is called a cell, and it is called a cellular system because the location registration of terminals and the execution and management of communication services are performed in cell units.

FIG. 5 is a diagram for explaining the outline of the CDMA cellular system. 10 is a cell, 11 and 12 are CDMA
Base stations 13 and 14 are mobile terminals. The CDMA base stations 11 and 12 are arranged in a distributed manner, and the reachable range of radio waves from the base station in one base station is the service area of the base station, that is, the cell. The CDMA base stations 11 and 12 can communicate with the mobile terminals 13 and 14 in the cell 10 by performing wireless communication according to the CDMA system.

Generally, in a CDMA cellular system, a plurality of base stations are arranged in a distributed manner, and the reach of radio waves at each base station is defined as the service area (cell) of that base station, and within each service area (cell). In, multiple channels are used for transmission and reception by code division multiple access using the same carrier frequency. Then, in order to enable continuous communication between the moving communication terminal and the base station, in a cell adjacent to a certain cell, the base station of the cell is used by the moving communication terminal. Communication is performed by CDMA using the same carrier frequency as the carrier frequency.

In the CDMA cellular system, since radio waves having the same carrier frequency are used in each of a plurality of adjacent cells, a signal from a mobile terminal belonging to a base station of another cell interferes with a receiving device of another base station. It is mixed as a signal. Usually, the CDMA interference signals from outside the own cell have unknown types of codes, code timings, transmission line response states, and the like, and therefore behave like noise in the receiving device of the base station.

By the way, there are two types of connection methods between the transmission / reception terminals when performing communication: connection (CO) type and connectionless (CL) type.

The connection (CO) type is a system that requires a procedure for confirming the sender and the receiver before starting communication and setting the communication line as shown in FIG. This method has the advantages that reliable communication is possible via the connected line and that information transfer after connection is simple, but it takes a long time to connect so that short data can be sent. Is not very efficient. This connection method is used for real-time communication that does not allow much delay.

On the other hand, the connectionless (CL) type is, as shown in FIG. 7, packetizes data to be sent together without establishing a communication line in advance, sends a packet to each destination with a destination, and the network side In this method, the destination is confirmed and delivered for each packet. With this method, it takes less time to connect, so even short data can be sent efficiently. However, it can be said that it is less reliable than the connection type.

[0010]

Code division multiple access (CDM) is one of communication methods in a cellular system.
A) is adopted. This is a method of spreading the energy of the original information bit in a wide band on the frequency axis for communication,
Compared to other methods, it excels in interference resistance, realization of path diversity, and ease of handoff.

By the way, the user capacity in CDMA is determined by the interference power (power of interference signal) from all multiple users. Therefore, in the CDMA system, very strict transmission power control is required for the mobile terminal in order to increase the user capacity. That is, there is a limit to the number of channels that can be multiplexed in one base station, and if the interference power exceeds that limit, communication becomes impossible.

Further, when considering multimedia communication in the future, it is necessary to guarantee communication quality that differs depending on the type of call. Considering the communication quality in such a CDMA system, the connection-type call must be able to guarantee higher quality than the connectionless-type call. Therefore, there is a need for a technique that can more reliably ensure such communication quality.

The present invention is intended to solve such a problem, and its object is to determine the communication quality in multimedia communication, particularly the communication quality for each call connection method (connection type or connectionless type). It is to provide a CDMA wireless communication system that can be guaranteed.

[0014]

In order to achieve the above-mentioned object, the wireless communication system of the present invention, as described in claim 1, when a base station makes a call from a mobile terminal or the mobile terminal. In a wireless communication system that allocates a code channel for communication with the mobile terminal when an incoming call is made to the mobile terminal, a connection type call and a connectionless type call in the base station
And a means for managing the number of multiplexed code channels and a number of the managed code channels and a number of code channels set to guarantee communication quality related to connection-type calls. Compare with the threshold value,
If the number of multiplexed managed code channels is small
Is both a connection-oriented and connectionless call
Is accepted and the managed code channel is higher than the threshold.
If the number of multiple calls is large, it is limited to connectionless calls.
Means for determining whether or not to permit the code channel allocation so as to accept a call back.

[0015]

More specifically, as described in claim 2 , the number of managed code channel multiplexes and the first threshold value and the second threshold value (where the first threshold value> the second threshold value) And when the code channel multiplex number is less than the second threshold value, the code channel assignment for connectionless and connection type calls is permitted, and the code channel multiplex number is equal to or more than the second threshold value. When it is less than the threshold value, the code channel allocation is permitted only for connectionless calls.

According to the first and second aspects of the present invention, in assigning code channels to connection-type and connectionless-type calls, an appropriate limit can be added in consideration of the limit of the number of code channel multiplexes. Type, connectionless type communication quality can be guaranteed. Further, it is possible to guarantee higher communication quality in the connection type than in the connectionless type.

[0018]

[0019]

[0020]

[0021]

Further, according to the present invention, as described in claim 3 , in the radio communication system according to claim 1 or 2, means for measuring the interference wave power from surrounding base stations in the base station. Further, by providing the means for setting the threshold value based on the measurement result of the interference wave power, it is possible to further improve the communication quality.

Furthermore, the present invention provides the wireless communication system according to claim 2 as described in claim 4 ,
When the mobile terminal is handed off during communication in each of the connectionless connection type and the connection type connection method, priority is given to the connection type call to allocate the code channel to improve connection type communication quality. Can be increased. Also, the code channel processing device of the present invention is, as described in claim 5 , a code channel for a base station to communicate with a mobile terminal when a call is made from a mobile terminal or when a call is received at the mobile terminal. Relating to the total number of code channel multiplexes of the connection-type call and the connectionless type call in the base station, and the number of managed code channel multiplexes and the connection-type call A threshold value indicating the number of multiplexed code channels set to guarantee communication quality is compared, and if the number of multiplexed code channels managed is smaller than the threshold value, a connection type call and a connectionless type call Both are accepted, and if the number of multiplexed code channels managed is larger than the threshold value, the call is accepted only for connectionless type calls. Characterized by comprising a means for determining whether to permit No. channel assignment. Further , the code channel processing device of the present invention is
As described in claim 6, means for assigning a code channel for the base station to communicate with the mobile terminal when an incoming call to the calling or when the mobile terminal from the mobile terminal, code channels in the base station Means for managing the number of multiplexes of the code channel, and the number of multiplexes of the managed code channel are compared with a first threshold value and a second threshold value (where the first threshold value> the second threshold value) Is less than the second threshold, the code channel allocation for connectionless and connection-type calls is permitted, and when the code channel multiplex number is equal to or more than the second threshold and less than the first threshold, the connectionless call And a means for permitting the code channel allocation.

[0024]

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

A connectionless type (hereinafter abbreviated as CL type) and a connection type (hereinafter, C) are provided between the base station and the mobile terminal in the CDMA communication system of this embodiment.
It is abbreviated as O type. ) It is possible to communicate with both connection methods. However, it is also possible to simultaneously perform CL-type and CO-type communication using a plurality of channels.

FIG. 1 shows the configuration of the base station. As shown in the figure, the base station includes an antenna 1, a transmitting / receiving unit 2, a channel processing unit 3, a network interface unit 4, an interference wave power measuring unit 5 and a control unit 6. Also,
As shown in FIG. 2, the channel processing unit 3 includes a channel management table 7, a channel allocation unit 8, and a connection method management unit 9.
Be equipped with.

The details of the embodiments according to each claim of the present invention will be described below.

(Embodiment according to claims 1 , 2, 5, and 6 ) The base station always sets the connection method (CL type, CO type) of the code channel with which the base station is currently communicating and the multiplexing number. Manage.

FIG. 3 shows an example of the channel management table 7 when the base station uses a plurality of carrier frequencies.
However, in this embodiment, there is one carrier frequency (F1).
I will assume that. In addition, the total number of communication code channels that can be used by one base station is MC (carrier frequency F1
, And certain values T1 and T2 (<MC) are threshold values for CL type and CO type, respectively. However, since the CO type connection method needs to guarantee a higher communication quality than the CL type connection method, T1> T2.

If the number of code channels communicating in CO type in a certain base station is TO1 and the number of code channels communicating in CL type is TL1, the current multiplex number TT in the base station is TT = TO1 + TL1. However, in the initial state, TO1 = TL1 = 0.

When the mobile terminal makes a call, the mobile terminal first selects the CL type or the CO type depending on the type of the call.
However, at this time, a plurality of channels (CL type and CO type) may be requested at the same time. For example, the CL type is selected when connecting to the Internet by sending e-mail or the like, and the CO type is selected when performing real-time communication in which delay is not allowed.

When a call request is issued from the mobile terminal to the base station, as shown in FIG. 4, in the base station, the connection request management unit 9 of the channel processing unit 3 requests that the call request is a CL type request. Or a CO type request (step A). When it is determined that the mobile terminal requests the base station for the CL type, the channel processing unit 3 of the base station refers to the channel management table 7 and compares the current multiplex number TT with the threshold value T1 ( In step B), if TT <T1 (step C), the channel allocation unit 8 accepts the request from the mobile terminal and allocates the code channel (step D). On the other hand, when TT> = T1, the base station does not allocate the code channel and drops the call (step E).

On the other hand, when a CO type is requested from the mobile terminal to the base station, the channel processing unit 3 of the base station similarly refers to the channel management table 7 to find the current multiplex number TT and the threshold value T2 (however, T1). > T2) (step F), and if TT <T2 (step G), the connection between the transmitting terminal and the receiving terminal is secured (step H).
When the connection can be secured, the request from the mobile terminal is accepted and the code channel is assigned (step I). On the other hand, when TT> = T2, the base station does not allocate the code channel to the mobile terminal, and the call is lost (step E).

Similarly, in the case of an incoming call to a mobile terminal, the channel processor 3 of the base station similarly sets the current multiplex number and the threshold T.
After making a comparison with T1 and T2, a code channel is assigned as in the case of a call.

When the mobile terminal moves to a cell managed by another base station and performs handoff, channel allocation in the destination base station is performed in the same manner as when the mobile terminal originates a call.

As described above, in this embodiment, different thresholds T1 and T are set for the CL-type and CO-type outgoing calls and incoming calls.
2 (however, T1> T2) is defined, and if the current code channel multiplex number TT is less than the threshold value T2, the code channel is permitted to be assigned to both the CO type call and the CL type call, Current code channel multiplex number T
When T is greater than or equal to the threshold T2 and less than the threshold T1, since it is permitted to allocate the code channel only to CL type calls,
In assigning the code channel to each of the CO type call and the CL type call, an appropriate limit can be added in consideration of the limit of the number of code channel multiplexes.
It is possible to guarantee the L-type communication quality. Further, higher communication quality can be guaranteed for the CO type than for the CL type.

( Reference Example ) It is assumed that one base station can use a plurality of carrier frequencies (carrier frequencies) F1 and F2. Then, the base station allocates the code channel of the carrier frequency F1 to the CL type request and the code channel of the carrier frequency F2 to the CO type request.

When the mobile terminal makes a call, first, CL type or CO type is selected depending on the type of call. However,
Multiple channels (CO type and CL type) may be requested at the same time. For example, the CL type is selected when connecting to the Internet by sending e-mail or the like, and the CO type is selected when performing real-time communication in which delay is not allowed.

In response to the call request from the mobile terminal, the base station determines whether the call request is a CL type request or a CO type request by the connection method management section 9 of the channel processing section 3. When it is determined that the mobile terminal requests the base station for the CL type, the channel allocating unit 8 of the base station checks whether or not the code channel of the carrier frequency F1 can be allocated, and if the code channel can be allocated. For example, a code channel is assigned to the mobile terminal. If it cannot be assigned, the call is lost without assigning the code channel to the mobile terminal.

On the other hand, when a CO type is requested from the mobile terminal to the base station, the channel allocation unit 8 of the base station checks whether the code channel of the carrier frequency F2 can be allocated, and if it can be allocated, the transmission is performed. Secure the connection between the terminal and the receiving terminal. When the connection can be secured, the request from the mobile terminal is accepted and the code channel is assigned to the mobile terminal. On the other hand, when the code channel cannot be assigned to the mobile terminal due to a lack of connections or lack of channels, the call loss occurs without assigning the code channel to the mobile terminal.

Further, there are three or more types of carrier frequencies (carrier frequencies) that can be used in one base station, that is, F1 and F.
If there are carrier frequencies of 2, ..., Fn, the carrier frequencies assigned to the CL type communication are F1 to Fm.
, And each carrier frequency is divided into two groups in advance so that the carrier frequencies assigned to the CO type communication are from F (m + 1) to Fn (where m <n) . The group may be used for CO type communication and CL type communication.

Also, instead of dividing the CO type communication channel and the CL type communication channel by the carrier frequency, the code channels usable per one carrier frequency are divided into two groups in advance, and The group of code channels of 1 may be assigned to CL type communication, and the other group of code channels may be assigned to CO type communication.

For example, when the total number of communication code channels usable on one carrier frequency is CC, the X code channel among them is used for CL type communication and the remaining (CC-X) channels are used for CO type communication. use.

As described above, according to this reference example , by using code channels having different carrier frequencies for CL type communication and CO type communication, or for CL type communication and CO type communication.
By grouping code channels used for type communication, it is possible to guarantee a certain quality for CL type communication and CO type communication, respectively.
By allowing more carrier frequencies and code channels to be allocated to the O-type communication, it is possible to ensure higher communication quality for the CO type than for the CL type.

(Embodiment according to Claim 3 ) The interference wave power measuring unit 5 of the base station can measure the interference wave power from the own base station and surrounding base stations. The base station manages the number of code channels (usable multiplex number) that can be communicated with the base station, which is determined by the measurement result of the interference wave power, in the channel management table 7 shown in FIG. That is, the number of usable multiplexes at the base station changes depending on the surrounding situation.

Therefore, in this embodiment, the thresholds T1 and T2 for the CL type and the CO type shown in the first embodiment are changed according to the number of communicable multiplexes.

For example, the communicable multiplex number at a certain time is T
When P is set, T2 = TP / 2 and T1 = TP . Then, for channel requests from the mobile terminal after this time point, code channels are assigned in the same manner as in the above-described embodiment according to the thresholds T1 and T2.

As described above, in this embodiment, the communication quality can be further improved by changing the threshold value according to the number of communicable multiplexes in the own base station determined by the measurement result of the interference wave power.

(Embodiment according to Claim 4 ) In FIG. 5, when the mobile terminal 13 communicating with the base station 11 moves and enters a cell managed by another base station 12, a handoff is performed. The mobile terminal 13 uses a plurality of connection methods (CL type, C type).
In the case of O type communication, the base station 12 of the moving destination is requested for code channels of a plurality of connection methods. Then, the base station 12 receives the request from the mobile terminal 13 from the channel processing unit 3
The connection method management unit 9 determines.

At this time, the movement-destination base station 12 refers to the channel management table 7 of the channel processing unit 3 to judge whether or not the request from the mobile terminal 12 can be satisfied, and when all the requests are satisfied. The channel allocator 8 allocates a code channel to the mobile terminal 12. When all the requests from the mobile terminal 12 cannot be satisfied, the channel allocation unit 8 prioritizes the CO type call and allocates the code channel.

The present invention is applicable not only to a code division multiple access system, but also to a TDMA (Time Division Multiple Access) by substituting slots for code channels.
It is also applicable to the method.

[0052]

As described above, according to the wireless communication system of the present invention, when assigning code channels to connection-type and connectionless-type calls, appropriate limits are added in consideration of the limit of the number of code channel multiplexes. Therefore, it is possible to guarantee connection-type and connectionless-type communication quality. Further, it is possible to guarantee higher communication quality in the connection type than in the connectionless type.

Further, according to the present invention, by using code channels having different carrier frequencies for connectionless communication and connection-oriented communication, it is possible to guarantee a certain quality for each connection method, Also, by allowing more carrier frequencies to be allocated to the connection type, it is possible to guarantee higher communication quality for the connection type than for the connectionless type.

Further, according to the present invention, by classifying the code channels used in connectionless communication and connection-oriented communication into groups, a certain quality can be guaranteed for each connection method, and more than in connectionless communication. By allowing more code channels to be allocated to the connection type, it is possible to guarantee higher communication quality for the connection type than for the connectionless type.

Further, according to the present invention, it is possible to further improve the communication quality by dynamically setting the threshold value based on the measurement result of the interference wave power.

Further, according to the present invention, when the mobile terminal hands off during the communication in each of the connectionless connection type and the connection type connection method, the connection type call is preferentially assigned to the code channel to thereby establish the connection. The communication quality of the mold can be further improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a base station in a CDMA system according to the present invention.

FIG. 2 is a diagram showing a configuration of a channel processing unit in the base station of FIG.

FIG. 3 is a diagram showing a configuration of a channel management table in the base station of FIG.

FIG. 4 is a flowchart showing a processing procedure of code channel allocation for CL type requests and CO type requests in the base station of FIG. 1;

FIG. 5 is a diagram for explaining a conventional CDMA system.

FIG. 6 is a diagram for explaining connection-oriented communication.

FIG. 7 is a diagram for explaining connectionless communication.

[Explanation of symbols]

1 ... antenna 2 ... Transceiver 3 ... Channel processing unit 4 ... Network interface 5 ... Interference wave power measurement unit 6 ... Control unit 7 ... Channel management table 8 ... Channel allocation unit 9: Connection method management section 10 ... cell 11, 12 ... Base station 13, 14 ... Mobile terminal

Front page continuation (72) Inventor Masahiro Iguchi 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Toshiba Research & Development Center Co., Ltd. (56) References JP-A-10-13937 (JP, A) JP-A-8 -331035 (JP, A) JP-A-8-317452 (JP, A) JP-A-9-84105 (JP, A) JP-A-7-283763 (JP, A) JP-A-8-289367 (JP, A) ) JP-A-8-9464 (JP, A) JP-A-10-107769 (JP, A) International Publication 96/031015 (WO, A1) Miki Hirano, "Management of ATM-PVC traffic that constitutes a CL type communication network" Of the Law ”, Proceedings of the 1994 Autumn Meeting of the Institute of Electronics, Information and Communication Engineers, September 5, 1994, Communications 2, p. 52, B-454 (58) Fields investigated (Int.Cl. ⁷ , DB name) H04J 13/00-13/06 H04B 1/69-1/713 H04B 7/26 H04Q 7/22 H04Q 7/28

Claims (6)

(57) [Claims] 1. A wireless communication system in which a base station allocates a code channel for communication with a mobile terminal when a call is made from a mobile terminal or when a call is received at the mobile terminal, wherein a connection-type call in the base station is provided. Means for managing the total number of code channel multiplexes for connectionless calls, and multiplex for the code channels set to guarantee communication quality relating to the managed number of code channels and connection type calls A threshold value indicating the number, and when the number of multiplexed code channels that are managed is smaller than the threshold value, both a connection-type call and a connectionless-type call are accepted, and the managed code is greater than the threshold value. When the number of multiplexed channels is large, a procedure for judging whether to permit the code channel allocation so that the call is accepted only for connectionless type calls. Wireless communication system, characterized by comprising and. 2. A wireless communication system in which a base station allocates a code channel for communication with the mobile terminal when a call is made from the mobile terminal or when a call is received at the mobile terminal, wherein the number of multiplexed code channels in the base station And a first threshold value and a second threshold value (wherein the first threshold value> the second threshold value), the code channel multiplexing number is When the number of code channels is less than the threshold value of 2, the code channel allocation for connectionless and connection type calls is permitted, and when the number of code channel multiplexes is equal to or more than the second threshold value and less than the first threshold value, the connectionless type call is limited to And a means for permitting code channel allocation. 3. An apparatus according to claim 1 or 2 or a wireless communication system, comprising: a means for measuring the interference signal power from the base station about the base station, the threshold value based on a measurement result of the interference power A wireless communication system further comprising: 4. The wireless communication system according to claim 2 , wherein when the mobile terminal performs handoff during communication in each of the connectionless connection type and the connection type connection method, the connection type call is given priority and the code is used. A wireless communication system further comprising means for allocating channels. 5. A means for allocating a code channel for a base station to communicate with a mobile terminal when a mobile terminal makes a call or receives a call to the mobile terminal, and a connection-oriented call and connectionless in the base station. Means for managing the total number of code channel multiplexes for the call type call, and the number of code channel multiplexes set for guaranteeing the communication number related to the managed code channel and the connection type call. Comparing with the threshold value shown, if the multiplex number of the managed code channel is smaller than the threshold value, accepts both connection-type call and connectionless-type call, and the managed code channel is higher than the threshold value. And a means for judging whether or not to permit the code channel allocation so that the call is accepted only for connectionless type calls when the number of multiplexing is large. Code channel processing apparatus according to claim and. 6. A means for allocating a code channel for a base station to communicate with a mobile terminal when a mobile terminal makes a call or receives a call to the mobile terminal, and managing the number of code channels multiplexed in the base station. And a first threshold value and a second threshold value (where the first threshold value> the second threshold value), and the code channel multiplex number is equal to the second threshold value. When the number of code channels is less than the threshold, the code channel allocation for connectionless and connection type calls is permitted, and when the code channel multiplex number is equal to or more than the second threshold value and less than the first threshold value, the code channel is limited to the connectionless type call. A code channel processing device, comprising: means for permitting allocation.