JP3657838B2 - Radio base station selection method, multicast method, radio base station, and radio terminal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radio base station selection method, a multicast method, a radio base station, and a radio terminal.
[0002]
[Prior art]
An idea that presupposes an IP (Internet Protocol) network as an access backbone network is widespread.
[0003]
There is IGMP (Internet Group Management Protocol) as a multicast protocol that can be realized on an IP network. IGMP is a protocol for determining whether or not a router sends multicast information to a subnetwork in order to avoid network congestion. As an access communication system connected to a network that supports IGMP, it is preferable to use an access control flow having affinity with IGMP.
[0004]
In IGMP, in order to avoid sending unnecessary information in the subnet, packets of group addresses that do not exist in the subnet are not multicast.
[0005]
Even in a radio access system that supports multicast, unnecessary information is not sent in the subnet, and radio resources are saved.
[0006]
However, if the same group exists in different routers A and B, the routers A and B perform multicast for the group in the respective subnets. Similarly, when different radio base stations have the same group, multicasting is performed for the group in each service area, and an operation similar to a router can be easily realized.
[0007]
In a wireless communication system in which a plurality of wireless base stations each cover a service area, the service areas of the wireless base stations are generally overlapped. In a situation where service areas overlap and there are a plurality of wireless base stations to which a wireless terminal can be connected, the wireless terminal is generally connected to a wireless base station with the best communication quality.
[0008]
FIG. 10 shows this state. The service area of the radio base station A is 1, and the service area of the radio base station B is 2.
[0009]
In FIG. 10A, the wireless terminal a is connected to the wireless base station A. The wireless terminal b can be connected to both the wireless base station A and the wireless base station B.
[0010]
However, since the wireless terminal b is located closer to the wireless base station B than the wireless base station A, the wireless terminal b is connected to the wireless base station B and receives a service in the hope that reception quality will be improved. .
[0011]
10B, when the service area 4 of the radio base station A exists in the service area 3 of the radio base station B, the radio terminal a is connected to the radio base station A and the radio base station B. Although it can be connected to both, it is connected to the radio base station A with the best communication quality.
[Problems to be solved by the invention]
In the conventional FIG. 10A, even when the wireless terminal b belongs to the same IGMP group (group GI) as the wireless terminal a and receives the same information, the wireless base station is selected based on the reception quality. The terminal a is connected to the wireless base station A, and the wireless base station A transmits the same information received by the wireless terminal b to the wireless terminal a.
[0012]
However, if there is no wireless terminal belonging to the same group other than the wireless terminal b in the area defined by the wireless base station B as the service area 2, if the wireless terminal b changes the connection to the wireless base station A, the wireless base station B The station B can stop the multicast to the wireless terminal b and use the bandwidth required for the transmission of the group G1 for other services.
[0013]
In addition, even when the service area 4 of the radio base station A exists in the service area 3 of the radio base station B as shown in FIG. 10B, it is most quality that the radio terminal a communicates with the radio base station A. Since the wireless terminal a is connected to the wireless base station A, the wireless base station A transmits the same information received by the wireless terminal c.
[0014]
However, since the wireless terminal a exists in an area where it can communicate with the wireless base station B, the wireless resource of the wireless base station A can be saved if the service is received from the wireless base station B.
[0015]
Conventionally, in the situation of a multicast service where wireless terminals connected to different wireless base stations belong to the same group and receive the same information, the same information is simultaneously transmitted by the respective wireless base stations. Cases arise.
[0016]
In such a case, since the same information is sent to the overlapping area, the radio resource is used twice, and the use efficiency of the radio resource is lowered.
[0017]
The present invention has been made in view of the above problems, and an object of the present invention is to increase the use efficiency of radio resources by reducing the number of radio base stations that transmit the same information to radio terminals.
[0018]
[Means for Solving the Problems]
The invention described in claim 1 is a radio base station selection method in which a radio terminal selects a radio base station to perform multicast, and the radio terminal can receive the same multicast information from a plurality of radio base stations. The wireless terminal selects a wireless base station so as to reduce the number of wireless base stations that transmit the same information.
[0019]
According to a second aspect of the present invention, in the radio base station selection method according to the first aspect,
When there is a wireless base station that can be connected to the wireless terminal and is transmitting multicast information to be received by the wireless terminal, the wireless terminal selects this wireless base station as a connection destination It is characterized by doing.
[0020]
The invention described in claim 3 is the radio base station selection method according to claim 1,
The wireless base station that can be connected to the wireless terminal, and when the wireless base station is selected from a plurality of wireless base stations that are transmitting multicast information that the wireless terminal is to receive, A feature is that a larger number of radio base stations are selected as connection destinations.
[0021]
The invention described in claim 4 is characterized in that the radio base station selected by the radio base station selection method according to any one of claims 1 to 3 performs multicasting.
[0022]
According to a fifth aspect of the present invention, in the radio base station that performs multicast to the radio terminal, the radio terminal is configured based on the selection by the radio terminal so as to reduce the number of radio base stations that transmit the same information. And multicasting.
[0023]
The invention described in claim 6 is a counter that counts down upon reception of a leave message from the wireless terminal and counts up upon reception of a participation message from the wireless terminal in a wireless base station that performs multicast to the wireless terminal. And transmitting the value of the counter to the wireless terminal.
[0024]
The invention described in claim 7 is characterized in that, in the radio base station according to claim 6, when the counter value is changed, the changed counter value is transmitted to the radio terminal.
[0025]
The invention described in claim 8 is characterized in that, in the radio base station according to claim 6 or 7, multicast is stopped when the counter value becomes zero.
[0026]
According to a ninth aspect of the present invention, in a wireless terminal that receives a multicast service from a wireless base station that performs multicast, an analysis unit that analyzes a control message from the wireless base station, and a number of wireless terminals that participate in the multicast service group A comparison unit for comparing, wherein the analysis unit detects the number of participating wireless terminals of a service group from a control message from the wireless base station, and the comparing unit compares the number of participating wireless terminals for each service group The radio base station is selected so as to reduce the number of radio base stations that transmit the same information.
[0027]
The selection naturally includes selection accompanying movement of the wireless terminal.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0029]
An embodiment of new multicast participation according to the present invention will be described with reference to FIG.
[0030]
The service area of the radio base station A is 1, and the service area of the radio base station B is 2.
[0031]
FIG. 1A shows a state before wireless terminal b participates, and FIG. 1B shows a state where wireless terminal b participates in accordance with the embodiment of the present invention.
[0032]
First, the wireless terminal a is connected to the wireless base station A as the multicast group G1. In this state, a new wireless terminal b tries to join the same group G1 (A).
[0033]
Note that the wireless terminal b exists at a position where it can be connected to the wireless base stations A and B.
[0034]
In this case, conventionally, the radio terminal b measures the quality of signals from both radio base stations and selects the radio base station that provides the best quality. However, in the present invention, the broadcast signal of the perch channel transmitted from the radio base station is analyzed, and it is known that the radio base station A is in service for the multicast group G1. The wireless terminal b selects a wireless base station A that is already in service, and receives multicast information from the wireless base station A (B).
[0035]
As a result, the radio base station B does not need to transmit a multicast to the group G1, and can allocate radio resources to other services.
[0036]
Next, an embodiment relating to radio base station switching in the multicast service of the present invention will be described with reference to FIG. The service area of the radio base station A is 1, and the service area of the radio base station B is 2.
[0037]
FIG. 2A shows a state before the wireless terminal b switches the wireless base station, and FIG. 2B shows a state where the wireless terminal b switches the wireless base station according to the embodiment of the present invention. It is.
[0038]
In FIG. 2, it is assumed that the wireless terminal a is connected to the wireless base station A, the wireless terminals b and c are connected to the wireless base station B, and each wireless terminal receives the service of the same multicast group G1 (A).
[0039]
Here, when the wireless terminal c moves and leaves the service area of the wireless base station B, only the wireless terminal b receives the G1 multicast service. The wireless terminal b is a wireless terminal that can be connected to both the wireless base stations A and B. Therefore, the wireless terminal b receives a service for switching the connection to the wireless base station A. As a result, the radio base station B can cancel the service for the group G1 and use the canceled radio resource for other services.
[0040]
With reference to FIG. 3, an embodiment relating to multicast services in overlapping service areas will be described.
[0041]
FIG. 3 shows a case where the service area 4 of the radio base station A exists in the area defined by the radio base station B as the service area 3 and the service areas overlap.
[0042]
FIG. 3A shows a state before the wireless terminal a switches the wireless base station, and FIG. 3B shows a state where the wireless terminal a switches the wireless base station according to the embodiment of the present invention. It is.
[0043]
First, it is assumed that the wireless terminal a is connected to the wireless base station A and belongs to the multicast group G1 and is receiving service (A).
[0044]
Next, the wireless terminal c is connected to the wireless base station B and participates in the group G1. In such a situation, both the radio base station A and the radio base station B transmit the same information.
[0045]
This embodiment avoids this. As will be described later, the radio base station transmits the number of radio terminals transmitted from the radio base station to the radio terminals via the perch channel for each multicast group.
[0046]
The wireless terminal a can be connected to both the wireless base station A and the wireless base station B. Accordingly, the wireless terminal a detects the number of wireless terminals transmitting from each wireless base station from the perch channels of both wireless base stations.
[0047]
The wireless terminal a compares the number of connected wireless terminals for each multicast group transmitted by the wireless base stations A and B. At this time, since the radio base station A has only the radio terminal a, the number of connected radio terminals is one. In the wireless base station B, the number of connected wireless terminals is 1 because the wireless terminal b is already connected. However, when the wireless terminal a participates, the number of connected wireless terminals increases to 2.
[0048]
In this case, the wireless terminal a operates to change the connection to the wireless base station B and increase the number of connected wireless terminals. As a result, only the radio base station B transmits to the group G1 (B).
[0049]
Next, the point that the number of wireless terminals transmitted by the wireless base station is notified to the wireless terminals for each multicast group will be described.
[0050]
Each radio base station needs to know that the radio terminal has stopped receiving its service due to movement, or that only one radio terminal remains in the service area. In addition, the wireless terminal side needs to know that only the group G1 service is received.
[0051]
For this reason, when a wireless terminal wants to receive a service, a participation message is transmitted to the wireless base station, and when leaving the group, a leaving message is transmitted. Each time the wireless base station receives the join and leave messages, the wireless base station counts up or down the number of wireless terminals currently receiving services for each group.
[0052]
The count result is reflected in the perch channel notification message and notified to the wireless terminal.
[0053]
As described with reference to FIG. 3, the wireless terminal that receives this notification message and can connect to a plurality of wireless base stations compares the number of wireless terminals in service and changes the connection to the larger one.
[0054]
In addition, the wireless base station stops the multicast service for a group in which there are no wireless terminals to receive the service.
[0055]
Transmission of participation and withdrawal of the wireless terminal can be performed by a conventional control message transmission method such as message transmission by random access or allocation of a dedicated control channel.
[0056]
The processing procedure on the radio base station side by joining and leaving is shown in FIGS.
[0057]
As shown in FIG. 4, when a wireless terminal desires to participate in a certain multicast group, a participation message is transmitted to the wireless base station. The radio base station receives the participation message (S11).
[0058]
The radio base station that has received the participation message counts up at the counter (S12). At the same time, the content of the number of participating wireless terminals in the notification message is updated (S13), and the notification message is transmitted (S14).
[0059]
Also, as shown in FIG. 5, when leaving from a participating group, a leave message is transmitted to the radio base station. The radio base station receives the leave message (S21). The received radio base station counts down the counter (S22) and recognizes a decrease in the number of group participating radio terminals. At the same time, the content of the number of participating wireless terminals in the notification message is updated (S23). As a result of the countdown, when the counter value becomes 0 (S24: YES), the scheduler in charge of radio resource allocation or the like is notified that there are no wireless terminals participating in the group (S25). Allocation of the allocated radio resource is stopped, and transmission of the information is stopped (S26). Thereafter, the notification message is updated, and the notification message in which the group participating wireless terminal is 0 is notified or the information regarding the group is deleted is transmitted (S27).
[0060]
If the counter value is not 0 (S24: NO), a notification message is transmitted (S27).
[0061]
The processing procedure on the wireless terminal side by participation is shown in FIG.
[0062]
In FIG. 6 and FIG. 7, a wireless terminal to which the wireless base station A and the wireless base station B can be connected is assumed.
[0063]
As shown in FIG. 6, a wireless terminal desiring to join a certain group first receives a notification message from the neighboring wireless base stations A and B (S31), and participates in the desired group of the notification message. The number of wireless terminals that are present is compared (S32). If there is no information on the group, the number of wireless terminals is interpreted as zero. For example, if the number of wireless terminals of the wireless base station A is larger, a participation message is transmitted to the wireless base station A (S33), and if the number of wireless terminals of the wireless base station B is larger, a participation message is transmitted to the wireless base station B (S34). The multicast service of the group is received (S34, 36).
[0064]
A case where a wireless terminal that has received a service from the wireless base station B switches to the wireless base station A will be described with reference to FIG.
[0065]
The wireless terminal receiving service from the wireless base station B (S41) intermittently receives notification messages from a plurality of nearby wireless base stations. Since the wireless base stations A and B can be connected, the wireless terminal knows the number of wireless terminals receiving service from the perch channel notification message from the wireless base station A and the wireless base station B. The numbers of participating wireless terminals of the wireless base station A and the wireless base station B are compared (S42). If the number of wireless terminals participating in the group is larger than that of the wireless base station B (S42: YES), a leave message is transmitted to B (S43), and the connection message is connected to A. Is transmitted (S44). As a result, the service of the multicast group of A is received (S45).
[0066]
If the wireless base station B has a larger number of participating wireless terminals in the group (S42: NO), the wireless base station is not switched.
[0067]
If the wireless terminal simply leaves, it is only necessary to transmit a leave message to the wireless base station.
[0068]
FIG. 8 shows a device configuration example of the radio base station of the present invention.
[0069]
The receiving unit 10 of the radio base station receives control messages such as joining and leaving in addition to receiving information. The message analysis unit 11 extracts a participation / leaving message and notifies the counter 12 thereof. The counter 12 counts up or down according to the notified contents, and notifies the notification message creating unit 13 when the counter value is changed. When the count value reaches 0, the radio resource scheduler 14 is notified and radio resource allocation is stopped. When there is a participation request from a wireless terminal that desires to join a new group, that is, when the counter value is changed from 0 to 1, the wireless resource scheduler 14 is notified of this, and the wireless resource for the new group is assigned. The multicast information is allocated and transmitted from the transmission unit 15. Further, the transmission unit 15 transmits the message created by the notification message creation unit 13.
[0070]
FIG. 9 shows a device configuration example of a wireless terminal.
[0071]
In addition to receiving information, the receiving unit 20 receives a control message such as a notification message. The message analysis unit 21 extracts the notification message and analyzes the number of participating wireless terminals in the service group. When a notification message is received from a plurality of radio base stations, the comparison unit 22 compares the number of participating radio terminals and determines whether or not to change the connection-destination radio base station. When changing the connection destination, the join / leave message creating unit 23 and the radio base station switching processing unit 24 are notified. If there is no need to change the connected radio base station, no particular processing is performed. The join / leave message creating unit 23 creates a message to send a leave message to the connected radio base station and a join message to the connection destination according to the contents notified from the comparison unit 22. In addition, a transmission destination notification is sent to the transmission unit 25 together with the transmission message. The transmission unit transmits these pieces of information. The radio base station switching processing unit 24 sets a state in which a participation message can be transmitted to the connection destination radio base station according to a procedure necessary for the system, such as synchronization with the connection destination radio base station.
[0072]
【The invention's effect】
As described above, according to the present invention, the following various effects can be achieved.
[0073]
The present invention relates to the number of radio base stations that serve radio terminals for the same information in a multicast service situation where radio terminals connected to different radio base stations belong to the same group and receive the same information. Can be reduced.
[0074]
For this reason, it is less likely that radio resources are assigned to the same information redundantly, radio resources can be used effectively, and the overall system capacity can be improved.
[0075]
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of new multicast participation.
FIG. 2 is a diagram for explaining an embodiment relating to switching of radio base stations during multicast service;
FIG. 3 is a diagram for explaining an embodiment relating to a multicast service in an overlapping service area;
FIG. 4 is a diagram illustrating a processing procedure of a radio base station in participation of a radio terminal.
FIG. 5 is a diagram illustrating a processing procedure of a radio base station when a radio terminal is disconnected.
FIG. 6 is a diagram illustrating a processing procedure of a wireless terminal in participation of the wireless terminal.
FIG. 7 is a diagram illustrating a processing procedure of a radio terminal in switching radio base stations.
FIG. 8 is a diagram illustrating a device configuration example of a radio base station according to the present invention.
FIG. 9 is a diagram illustrating a device configuration example of a wireless terminal according to the present invention.
FIG. 10 is a diagram showing a conventional technique.
[Explanation of symbols]
1 to 4 Service areas 10 and 20 of the radio base station Reception unit 11 Message analysis unit 12 Counter 13 Broadcast message creation unit 14 Radio resource scheduler 15 and 25 Transmission unit 21 Analysis unit 22 Comparison unit 23 Join / leave message creation unit 24 Radio base station switching processor

Claims (9)

A radio base station selection method in which a radio terminal selects a radio base station to perform multicasting,
When the same multicast information can be received from a plurality of radio base stations in the radio terminal,
A radio base station selection method, wherein a radio terminal selects a radio base station so as to reduce the number of radio base stations that transmit the same information. In the radio base station selection method according to claim 1,
When there is a wireless base station that can be connected to the wireless terminal and is transmitting multicast information that the wireless terminal intends to receive,
The radio base station selection method, wherein the radio terminal selects the radio base station as a connection destination. In the radio base station selection method according to claim 1,
The wireless base station that can be connected to the wireless terminal, and when the wireless base station is selected from a plurality of wireless base stations that are transmitting multicast information that the wireless terminal is to receive, A method of selecting a radio base station, comprising selecting a larger number of radio base stations as connection destinations. A multicast method wherein a radio base station selected by the radio base station selection method according to claim 1 performs multicast. In a radio base station that performs multicast to radio terminals,
A radio base station that performs multicast to the radio terminal based on selection by the radio terminal so as to reduce the number of radio base stations that transmit the same information. In a radio base station that performs multicast to radio terminals,
A counter that counts down upon receipt of a leave message from the wireless terminal and counts up upon receipt of a join message from the wireless terminal;
A radio base station that transmits the value of the counter to the radio terminal. The radio base station according to claim 6,
A radio base station, wherein when the counter value is changed, the changed counter value is transmitted to the radio terminal. In the radio base station according to claim 6 or 7,
Multicast is stopped when the counter value reaches 0. In a wireless terminal that receives a multicast service from a wireless base station that performs multicasting,
An analysis unit for analyzing a control message from the radio base station;
A comparison unit that compares the number of participating wireless terminals of the multicast service group,
The analysis unit detects the number of participating wireless terminals of a service group from a control message from the wireless base station, and the comparing unit compares the number of participating wireless terminals for each service group, thereby transmitting the same information. A radio terminal characterized by selecting a radio base station so as to reduce the number.

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