Antenna divison multiple access

• US 20050195784A1
• Filed: 03/07/2005
• Published: 09/08/2005
• Est. Priority Date: 03/05/2004
• Status: Active Grant

• Current Assignee: Ramot at Tel Aviv University Limited (Tel Aviv University)
• Original Assignee: Ramot at Tel Aviv University Limited (Tel Aviv University)
• Inventors: Atzmon, Yoav, Freedman, Avraham
• Granted Patent: US 7,630,349 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 2001/0092 Error control systems characterised by the topology of the transmission link
• CPC Class Codes: H04W 74/004 in the uplink, i.e. towards network
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

Three or more nodes, each with a plurality of antennas, communicate by transmitting messages simultaneously to each other. One of the nodes transmits two messages to two different destination nodes using different sets of its antennas. A receiving node receives at least two of the messages as a received signal, and uses a spatial demultiplexing algorithm such as VBLAST to extract from the received signal at least one message for which the receiving node is a destination node. Before the messages are transmitted, it is decided how many of its antennas each node is allowed to use to transmit each of its messages. For that purpose, the nodes exchange RTSs (Request To Send messages) and CTSs (Clear To Send messages). Collisions among the nodes are resolved. A transmission power and a route are selected for each message.

Claims

1. A method of communication among at least three nodes, each node including a plurality of antennas, the method comprising the steps of:

(a) each of at least one transmitting node transmitting a first respective message to a destination node of said first respective message, using at least one antenna of said each transmitting node;

(b) one of said at least one transmitting node transmitting a second message to a destination node of said second message, using at least one other antenna of said one transmitting node, said destination node of said second message being different from said destination node of said first message;

wherein all said transmitting is effected substantially simultaneously; and

(c) at one of said nodes;

(i) receiving at least two said messages as a received signal; and

(ii) extracting, from said received signal, at least one of said messages for which said one node is a destination node, said extracting being effected using a spatial demultiplexing algorithm.

2. The method of claim 1, wherein said spatial demultiplexing algorithm is a VBLAST algorithm.

3. The method of claim 1, further comprising the step of:

(d) prior to said transmitting, deciding, for each said node that is a source node, how many of the antennas thereof said each source node is allowed to use for transmitting each said message that said each source node seeks to transmit.

4. The method of claim 3, wherein said deciding is effected by steps including:

(i) each said source node broadcasting, for each said message that said each source node desires to transmit, a respective RTS that includes a desired number of antennas for transmitting said each message;

(ii) each said node, that receives at least one said RTS, broadcasting, for each said at least one RTS, a corresponding CTS that includes an allowed number of antennas; and

(iii) each said source node adjusting said at least one desired number of antennas thereof in accordance with said at least one CTS that is received by said each source node.

5. The method of claim 4, wherein each said RTS includes a training set.

6. The method of claim 4, wherein said transmitting is effected during a time slot, and wherein said deciding is effected by steps further including:

(iv) allocating a plurality of RTS mini-slots, at a start of said time slot; and

(v) allocating a plurality of CTS mini-slots, immediately following said plurality of RTS mini-slots;

such that each said source node broadcasts each said respective RTS thereof during one of said RTS mini-slots and each said node that receives at least one said RTS broadcasts each said corresponding CTS during one of said CTS mini-slots.

7. The method of claim 6, wherein, for each said source node, for each said respective RTS that is broadcast by said each source node, said RTS mini-slot, during which said each source node broadcasts said each respective RTS, is selected randomly;

and wherein, for each said node that receives at least one said RTS, for each said corresponding CTS, said CTS mini-slot, during which said each node that receives at least one said RTS broadcasts said each corresponding CTS, is selected randomly.

8. The method of claim 7, wherein said a number of said RTS mini-slots and a number of said CTS mini-slots are selected so that a probability of every said RTS being received by all nodes within transmission range of said node that broadcasts said RTS is at least a predetermined value and so that a probability of every said CTS being received by all nodes within transmission range of said node that broadcasts said CTS is at least said predetermined value.

9. The method of claim 3, further comprising the step of:

(e) resolving collisions among the nodes.

10. The method of claim 9, wherein said resolving is effected by steps including:

(i) partitioning the nodes among at least one chain of decreasing desired numbers of transmitting antennas, each said chain including a final node; and

(ii) forbidding said at least one final node to transmit.

11. The method of claim 1, further comprising the step of:

(d) for each said message, selecting a corresponding transmission power.

12. The method of claim 11, wherein said selecting of said transmission powers is effected in a manner that substantially equalizes minimum signal-to-interference ratios of all said destination nodes.

13. The method of claim 1, further comprising the step of:

(d) selecting a respective route of each said message.

14. The method of claim 13, wherein, for each said message, said respective route is selected to minimize a metric related to interference of nodes other than said transmitting node that transmits said each message and said destination node of said each message.

15. The method of claim 14, wherein said metric includes a sum of a cost of hard blockages along said respective route and a cost of soft blockages along said respective route.

16. A method of communication among at least three nodes, each node including a plurality of antennas, the method comprising the steps of:

(a) each of at least two transmitting nodes substantially simultaneously transmitting a respective message to a common destination node, using at least one antenna of said each transmitting node; and

(b) said common destination node;

(i) receiving said messages as a received signal using at least as many of the antennas of said common destination node as a total number of antennas that are used by said at least two transmitting nodes to transmit said messages, and

(ii) extracting at least one of said messages from said signal using a spatial demultiplexing algorithm.