# US 10,122,540 B2 · Device and method for managing multicast group in wireless network

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 10,122,540 B2
- Document ID: US10122540B2
- Status: Granted
- Kind: B2
- Application number: 14/947,402
- Filed: 2015-11-20
- Published: 2016-03-17
- Granted: 2018-11-06
- Earliest claimed: 2013-05-30
- Assignees: Chung-Ang University-Academy Cooperation Foundation
- Applicants: Chung-Ang University-Academy Cooperation Foundation
- Inventors: Sung Rae Cho; Jun Beom Hur; Woong Soo Na; Jeong Seok Yu; Tae Jin Kim; Hyoung Chel Bae; Yun Seong Lee; Ju Ho Lee; Zeynep Vatandas
- Web page: https://patentgrep.com/patent/US10122540B2

## CPC

- H04L 12/185: {with management of multicast group membership}
- H04L 12/189: {in combination with wireless systems (selective distribution or broadcast in wireless communication networks H04W4/06)}
- H04W 4/06: Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

A wireless device and method for managing a multicast group within a wireless network are disclosed. The wireless device is included in a first multicast group in which data is directly sent between member devices or data is sent using hopping between the member devices. The wireless device includes a reception unit, a determination unit, and a transmission unit. The reception unit receives a join request for joining a second multicast group from a joining device that attempts to join the second multicast group. The determination unit extracts information about the second multicast group from the join request, and determines whether the second multicast group is identical with the first multicast group based on the information about the second multicast group. The transmission unit forwards the join request to another device or sends a response to the join request to the joining device based on a result of the determination.

## Claims

### Claim 1

A wireless device included in a first multicast group in which data is directly sent between member devices or data is sent using hopping between the member devices, the wireless device comprising:
a receiver configured to receive a join request for joining a second multicast group from a joining device that attempts to join the second multicast group;
a processor circuitry configured to:
extract information about the second multicast group from the join request; and
determine whether the second multicast group is identical with the first multicast group based on the information about the second multicast group; and
a transmitter configured to forward the join request to another device or send a response to the join request to the joining device based on a result of the determination,
wherein the transmitter is further configured to send the response to the join request to the joining device if the second multicast group is identical with the first multicast group;
the transmitter is further configured to send a redundant transmission prevention message to a second member device included in the second multicast group; and
the redundant transmission prevention message is used to prevent the second member device from sending a response to the join request to the joining device even if the join request has been sent to the second member device.

### Claim 2 (depends on 1)

The wireless device of claim 1, wherein:
the processor circuitry is further configured to determine a number of hops from the joining device to the wireless device; and
the transmitter is further configured to discard the join request if the determined number of hops is larger than a predetermined number.

### Claim 3

A joining device attempting to join a first multicast group in which data is directly sent between member devices or data is sent using hopping between the member devices, the joining device comprising:
a transmitter configured to send a join request for joining the first multicast group to a member device included in a second multicast group; and
a receiver configured to receive a response to the join request from the member device if the first multicast group is identical with the second multicast group;
wherein whether the first multicast group is identical with the second multicast group is determined by comparing information about the first multicast group, extracted from the join request, with information about the second multicast group; and
wherein the join request is sent to another device if the first multicast group is not identical with the second multicast group;
a redundant transmission prevention message is sent from the member device to another member device included in the second multicast group if the first multicast group is identical with the second multicast group; and
the redundant transmission prevention message is used to prevent the another member device from sending a response to the join request to the joining device even if the join request has been sent to the another member device.

### Claim 4 (depends on 3)

The joining device of claim 3, wherein the join request is discarded if a number of hops from the joining device to the member device is larger than a predetermined number.

### Claim 5

A member device included in a multicast group, the member device comprising:
a processor circuitry configured to determine that the multicast group has been damaged if information about the multicast group has not been received from a withdrawing device included in the multicast group for a specific time;
a transmitter configured to send restoration information about the multicast group to a second member device included in the multicast group based on a result of the determination; and
a receiver configured to:
receive a response to the restoration information from the second member device; and
restore the multicast group using the response,
receive the information about the multicast group from the second member device included in the multicast group; and
the processor circuitry is further configured to:
estimate a damaged location based on the information about the multicast group received from the second member device and the withdrawing device; and
set a timer based on a result of the estimation.

### Claim 6 (depends on 5)

The member device of claim 5, wherein the information about the multicast group is included and received in a multicast group notification frame (MGNF).

### Claim 7 (depends on 5)

The member device of claim 5, wherein the transmitter sends the restoration information about the multicast group when the set timer expires.

### Claim 8 (depends on 5)

The member device of claim 5, wherein the timer is set to a value proportional to a distance between the damaged location and the member device or a number of hops between the damaged location and the member device.

### Claim 9 (depends on 5)

The member device of claim 5, wherein the restoration information about the multicast group is included and sent in an advertisement command frame (ACF).

### Claim 10 (depends on 9)

The member device of claim 9, wherein the advertisement command frame is sent only up to a wireless device spaced apart from the member device by a predetermined number of hops.