COOPERATIVE TRANSMISSION IN WIRELESS COMMUNICATION SYSTEM

• US 20110170450A1
• Filed: 09/23/2008
• Published: 07/14/2011
• Est. Priority Date: 09/23/2008
• Status: Active Grant

• Current Assignee: HMD Global Oy
• Original Assignee: Nokia Solutions and Networks US LLC (Nokia Corporation)
• Inventors: Kangas, Maria, Juntti, Markku
• Granted Patent: US 9,112,695 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 1/1825 Adaptation of specific ARQ protocol parameters according to transmission conditions
• CPC Class Codes: H04L 1/1867 Arrangements specially adapted for the transmitter end
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 2001/0092 Error control systems characterised by the topology of the transmission link
• CPC Class Codes: H04W 40/22 using selective relaying for reaching a BTS [Base Transceiver Station] or an access point

Abstract

A method, apparatus, and computer program for cooperative transmission are provided. A re-transmitter for a data packet determined as not having been received at a re-ceiver correctly is selected amongst the potentialre-transmitters in a cooperative transmission mode. In more detail, the re-transmitter is selected amongst an original transmitter of the data packet and assisting transmitters configured to assist transmission of the original transmit-ter. The assisting transmitters receive the data packet in the original transmission, unless errors occur in the reception at a given assisting transmitter, and are candidates for the retransmission in case the original transmission results in erroneous reception at the receiver.

Claims

1. A method, comprising:

establishing a cooperative data transmission mode, wherein at least one wireless communication device is an assisting transmitter and a potential re-transmitter for another wireless communication device being an original transmitter of a data packet destined to a receiver;

determining whether or not a data packet transmitted by the original transmitter is received at the receiver; and

selecting, when the receiver is determined as not having received the data packet, a re-transmitter among the original transmitter and the at least one assisting transmitter having received the data packet from the original transmitter in a previous transmission and decoded the data packet.

2. The method of claim 1, wherein the receiver is determined to have received the data packet upon reception of a positive acknowledgment message from the receiver, and wherein the receiver is determined to not have received the data packet upon reception of a negative acknowledgment message received from the receiver or upon reception of no acknowledgment message from the receiver.

3. The method of claim 1, further comprising:

controlling the selection of the re-transmitter with acknowledgment messages exchanged between the wireless communication devices in the cooperative data transmission mode.

4. The method according to claim 1, wherein the selection further comprises:

selecting as the re-transmitter an assisting transmitter which has decoded the data packet error-freely; and

selecting the original transmitter as the re-transmitter, if no assisting transmitter has decoded the data packet error-freely.

5. The method according to claim 1, further comprising:

receiving, from the receiver in the assisting transmitter, a plurality of acknowledgment messages related to data packets transmitted by the assisting transmitter;

monitoring the quality of a communication channel between the assisting transmitter and the receiver on the basis of the received acknowledgment messages; and

selecting the re-transmitter on the basis of the monitored channel quality.

6. The method of claim 5, wherein the monitoring comprises:

counting the number of received positive acknowledgment messages and/or received negative acknowledgment messages within a determined period of time, wherein reception of no acknowledgment message with respect to a given data packet is deemed as a negative acknowledgment message; and

approximating the channel quality on the basis of the number of positive and/or negative acknowledgment messages received within the determined period of time.

7. The method of claim 5, wherein the monitoring comprises:

determining the instantaneous quality of the communication channel on the basis of the latest determined acknowledgment for a data packet transmitted from the assisting transmitter.

8. The method according to claim 5, wherein the selection of the re-transmitter further comprises:

comparing the quality of the communication channel with a predetermined threshold level; and

selecting the assisting transmitter as the re-transmitter for the data packet, if the comparison indicates that the quality of the communication channel is better than the predetermined threshold level.

9. The method of claim 8, further comprising:

receiving from the original transmitter a data packet destined to the receiver, wherein the data packet comprises information indicating the quality of a communication channel between the original transmitter and the receiver;

using the quality of the communication channel between the original transmitter and the receiver as the predetermined threshold level.

10. The method of claim 9, wherein the selection of the re-transmitter further comprises:

selecting the assisting transmitter as the re-transmitter, if the channel quality of the assisting transmitter is better than the channel quality of the original transmitter regardless of whether or not the data packet has been decoded error-freely in the assisting transmitter.

11. The method according to claim 5, further comprising:

receiving a data packet destined to the receiver at the assisting transmitter;

decoding the received data packet and checking if the data packet comprises errors after the decoding;

if the data packet is decoded error-freely and if the quality of the communication channel is better than the predetermined threshold level, transmitting a positive acknowledgment indicating the error-free reception of the data packet to the original transmitter as an indication that the assisting transmitter is the re-transmitter for the data packet.

12. The method of claim 1, wherein only one wireless communication device is selected as the re-transmitter.

25. A computer program product embodied on a distribution medium readable by a computer and comprising program instructions which, when loaded into an apparatus, execute the method according to claim 1.

13. An apparatus, comprising:

an interface to enable a communication connection; and

a controller configured to establish a cooperative data transmission mode, wherein at least one wireless communication device is an assisting transmitter and a potential re-transmitter for another wireless communication device being an original transmitter of a data packet destined to a receiver, to determine whether or not a data packet transmitted by the original transmitter is received at the receiver, and to select, when the receiver is determined as not having received the data packet, a re-transmitter among the original transmitter and the at least one assisting transmitter having received and decoded the data packet from the original transmitter in a previous transmission.

14. The apparatus of claim 13, wherein the receiver is determined to have received the data packet upon reception of a positive acknowledgment message from the receiver, and wherein the receiver is determined to not have received the data packet upon reception of a negative acknowledgment message received from the receiver or upon reception of no acknowledgment message from the receiver.

15. The apparatus of claim 13, wherein the controller is further configured to control the selection of the re-transmitter with acknowledgment messages exchanged between the wireless communication devices in the cooperative data transmission mode.

16. The apparatus according to claim 13, wherein the controller is further configured to select as the re-transmitter an assisting transmitter which has decoded the data packet error-freely, and to select the original transmitter as the re-transmitter, if no assisting transmitter has decoded the data packet error-freely.

17. The apparatus according to claim 13, wherein the controller is applicable to the assisting transmitter and further configured to receive, from the receiver through the interface, a plurality of acknowledgment messages related to data packets transmitted by the assisting transmitter, to monitor the quality of a communication channel between the assisting transmitter and the receiver on the basis of the received acknowledgment messages, and to select the re-transmitter on the basis of the monitored channel quality.

18. The apparatus of claim 17, wherein the controller is further configured to count the number of received positive acknowledgment messages and/or received negative acknowledgment messages within a determined period of time, wherein reception of no acknowledgment message with respect to a given data packet is deemed as a negative acknowledgment message, and to approximate the channel quality on the basis of the number of positive and/or negative acknowledgment messages received within the determined period of time.

19. The apparatus of claim 17, wherein the controller is further configured to determine an instantaneous quality of the communication channel on the basis of the latest determined acknowledgment for a data packet transmitted from the assisting transmitter.

20. The apparatus according to claim 17, wherein the controller is further configured to compare the quality of the communication channel with a predetermined threshold level, and to select the assisting transmitter as the re-transmitter for the data packet, if the comparison indicates that the quality of the communication channel is better than the predetermined threshold level.

21. The apparatus of claim 20, wherein the controller is further configured to receive from the original transmitter a data packet destined to the receiver, wherein the data packet comprises information indicating the quality of a communication channel between the original transmitter and the receiver, and to use the quality of the communication channel between the original transmitter and the receiver as the predetermined threshold level.

22. The apparatus of claim 21, wherein the controller is further con-figured to select the assisting transmitter as the re-transmitter, if the channel quality of the assisting transmitter is better than the channel quality of the original transmitter regardless of whether or not the data packet has been decoded error-freely in the assisting transmitter.

23. The apparatus according to claim 17, wherein the controller is further configured to receive a data packet destined to the re-ceiver at the assisting transmitter, to decode the received data packet, to check whether or not the data packet comprises errors after the decoding, and if the data packet is decoded error-freely and if the quality of the communication channel is better than the predetermined threshold level, to send a positive acknowledgment indicating the error-free reception of the data packet to the original transmitter as an indication that the assisting transmitter is the re-transmitter for the data packet.

24. An apparatus, comprising:

means for establishing a cooperative data transmission mode, wherein at least one wireless communication device is an assisting transmitter and a potential re-transmitter for another wireless communication device being an original transmitter of a data packet destined to a receiver;

means for determining whether or not a data packet transmitted by the original transmitter is received at the receiver; and

means for selecting, when the receiver is determined as not having received the data packet, a re-transmitter among the original transmitter and the at least one assisting transmitter having received the data packet from the original transmitter in a previous transmission and decoded the data packet.