COMMUNICATIONS TERMINAL, COMMUNICATIONS METHOD, AND PROGRAM AND INTEGRATED CIRCUIT FOR COMMUNICATION

• US 20120158818A1
• Filed: 05/17/2011
• Published: 06/21/2012
• Est. Priority Date: 06/28/2010
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Muramoto, Eiichi, Baduge, Thilmee Malinda
• Granted Patent: US 9,184,928 B2
• Time in Patent Office: Days
• US Class Current: 709/201
• CPC Class Codes: H04L 12/1854 with non-centralised forwarding system, e.g. chaincast
• CPC Class Codes: H04L 12/1868 Measures taken after transmission, e.g. acknowledgments
• CPC Class Codes: H04N 21/6405 Multicasting data broadcast and multicast in packet switching networks H04L12/18

Abstract

A communication terminal (100) is one of communication terminals each having one parent terminal and zero or more child terminals. The communication terminals form an Application Layer Multicast (ALM) tree to sequentially distribute retransmission data of stream data from the parent terminal to the child terminal. The communications terminal (100) includes: a reproduction delay time determining unit (1010) determining a reproduction delay time based on a longest round-trip delay time among round-trip delay times of sections between a root terminal and the communications terminal (100), each of the round-trip delay times being required for transmission and reception of data through one of the sections between two neighboring terminals of the communications terminals on the ALM tree; and a reproduction control unit (1020) reproducing the stream data received from the root terminal, with the stream data delayed by the reproduction delay time determined by the reproduction delay time determining unit (1010).

Claims

1. A communications terminal included in communications terminals each of which receives stream data distributed from a root terminal and reproduces the stream data, each of the communications terminals having one parent terminal and zero or more child terminals, such that the communication terminals form an Application Layer Multicast (ALM) tree to sequentially transmit retransmission data of the stream data from the parent terminal to the child terminal, and said communications terminal comprising:

a reproduction delay time determining unit configured to determine a reproduction delay time based on a longest round-trip delay time among round-trip delay times of sections between the root terminal and said communications terminal, each of the round-trip delay times being required for transmission and reception of data through one of the sections between two neighboring terminals of the communications terminals on the ALM tree; and

a reproduction control unit configured to reproduce the stream data received from the root terminal, with the stream data delayed by the reproduction delay time determined by said reproduction delay time determining unit.

2. The communications terminal according to claim 1,

wherein said reproduction delay time determining unit is configured to determine, as the reproduction delay time, an integral multiple of the longest round-trip delay time.

3. The communications terminal according to claim 1,

wherein when a round-trip delay time between said communications terminal and the parent terminal is defined as rtt(self), the reproduction delay time of said communications terminal is defined as x(self), the reproduction delay time of the parent terminal is defined as x(parent), and a positive integer is defined as α

_self,

said reproduction delay time determining unit determines

(i) the reproduction delay time x(self) by means of Expression 1 if rtt(self)≧

x(parent) is satisfied and

(ii) the reproduction delay time by means of Expression 2 if rtt(self)<

x(parent) is satisfied;

X(self)=α

_self×

rtt(self); and

 

 

(Expression

     1)

X(self)=(α

_self−

1)×

rtt(self)+x(parent). 

 

(Expression

     2)

4. The communications terminal according to claim 1, further comprising

a retransmission requesting unit configured to, in the case where part of the stream data received from the root terminal is lost, request the parent terminal to transmit retransmission data corresponding to the loss,

wherein said retransmission request unit is configured to repeatedly request the parent terminal to transmit the retransmission data at an interval which is (i) equal to or longer than the round-trip delay time between said communications terminal and the parent terminal and (ii) equal to or shorter than the longest round-trip delay time.

5. The communications terminal according to claim 1, further comprising:

a round-trip delay time measuring unit configured to measure the round-trip delay time between said communications terminal and the parent terminal; and

a round-trip delay time managing unit configured to (i) receive, from the parent terminal, a round-trip delay time notification including one or more of the round-trip delay times between the root terminal and the parent terminal on the ALM tree and (ii) transmit, to the child terminal, the received round-trip delay time notification together with the round-trip delay time measured by said round-trip delay time measuring unit.

6. The communications terminal according to claim 5,

wherein said round-trip delay time managing unit is configured to receive the round-trip delay time notification at predetermined time intervals,

said round-trip delay time measuring unit is configured to measure the round-trip delay time between said communications terminal and the parent terminal at each reception of the round-trip delay time notification, and

at each reception of the round-trip delay time notification, said reproduction delay time determining unit is configured to determine the reproduction delay time based on the one or more round-trip delay times included in the round-trip delay time notification and the round-trip delay time measured by said round-trip delay time measuring unit.

7. A communications terminal included in communications terminals each of which receives stream data distributed from a root terminal and reproduces the stream data,

each of the communications terminals having one parent terminal and zero or more child terminals, such that the communication terminals form an ALM tree to sequentially transmit retransmission data of the stream data from the parent terminal to the child terminal, and said communications terminal comprising:

a reproduction delay time determining unit configured to determine a reproduction delay time based on a round-trip delay time of which section, among sections between the root terminal and said communications terminal, has a greatest loss rate of the stream data, each of round-trip delay times being required for transmission and reception of data through one of the sections between two neighboring terminals of the communications terminals on the ALM tree; and

a reproduction control unit configured to reproduce the stream data, with the stream data delayed, upon reception of the stream data, by the reproduction delay time determined by said reproduction delay time determining unit.

8. The communications terminal according to claim 7, further comprising:

a loss rate measuring unit configured to measure the loss rate between said communications terminal and the parent terminal; and

a loss rate managing unit configured to (i) receive, from the parent terminal, a loss rate notification including one or more loss rates between the root terminal and the parent terminal on the ALM tree and (ii) transmit, to the child terminal, the loss rate notification together with the loss late measured by said loss rate measuring unit.

9. The communications terminal according to claim 8,

wherein said loss rate managing'"'"'unit is configured to receive the loss rate notification at predetermined time intervals,

said loss rate measuring unit is configured to measure the loss rate between said communications terminal and the parent terminal at each reception of the loss rate notification, and

at each reception of the loss rate notification, said reproduction delay time determining unit is configured to determine the reproduction delay time based on the one or more loss rates included in the loss rate notification and the loss rate measured by said loss rate measuring unit.

10. A communications method executed by a communications terminal included in communications terminals each of which receives stream data distributed from a root terminal and reproduces the stream data,

each of the communications terminals having one parent terminal and zero or more child terminals, such that the communication terminals form an ALM tree to sequentially transmit retransmission data of the stream data from the parent terminal to the child terminal, and said communications method comprising:

determining a reproduction delay time based on a longest round-trip delay time among round-trip delay times of sections between the root terminal and the communications terminal, each of the round-trip delay times being required for transmission and reception of data through one of the sections between two neighboring terminals of the communications terminals on the ALM tree; and

reproducing the stream data received from the root terminal, with the stream data delayed by the reproduction delay time determined in said determining.

11. A program stored on a non-transitory computer-readable recording medium and executed by a communications terminal included in communications terminals each of which receives stream data distributed from a root terminal and reproduces the stream data,

each of the communications terminals having one parent terminal and zero or more child terminals, such that the communication terminals form an ALM tree to sequentially transmit retransmission data of the stream data from the parent terminal to the child terminal, and said program causing the communications terminal to execute:

determining a reproduction delay time based on a longest round-trip delay time among round-trip delay times of sections between the root terminal and the communications terminal, each of the round-trip delay times being required for transmission and reception of data through one of the sections between two neighboring terminals of the communications terminals on the ALM tree; and

reproducing the stream data received from the root terminal, with the stream data delayed by the reproduction delay time determined in said determining.

12. An integrated circuit in a communications terminal included in communications terminals each of which receives stream data distributed from a root terminal and reproduces the stream data,

each of the communications terminals having one parent terminal and zero or more child terminals, such that the communication terminals form an ALM tree to sequentially transmit retransmission data of the stream data from the parent terminal to the child terminal, and said integrated circuit comprising:

a reproduction delay time determining unit configured to determine a reproduction delay time based on a longest round-trip delay time among round-trip delay times of sections between the root terminal and said communications terminal, each of the round-trip delay times being required for transmission and reception of data through one of the sections between two neighboring terminals of the communications terminals on the ALM tree; and

a reproduction control unit configured to reproduce the stream data received from the root terminal, with the stream data delayed by the reproduction delay time determined by said reproduction delay time determining unit.