Systems and Methods for Multi-Beam Optic-Wireless Vehicle Communications

• US 20090310608A1
• Filed: 07/23/2008
• Published: 12/17/2009
• Est. Priority Date: 07/23/2007
• Status: Active Grant

• Current Assignee: Telcordia Technologies Incorporated (Telefonaktiebolaget LM Ericsson), Toyota Infotechnology Center Co., Ltd. (Toyota Motor Corporation)
• Original Assignee: Telcordia Technologies Incorporated (Telefonaktiebolaget LM Ericsson), Toyota Infotechnology Center USA, Inc.
• Inventors: Lee, John, Vuyyuru, Rama, Chen, Wai, Guha, Ratul K., Onishi, Ryokichi
• Granted Patent: US 8,068,463 B2
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04L 45/48 Routing tree calculation
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• CPC Class Codes: H04W 40/06 based on characteristics of available antennas
• CPC Class Codes: H04W 76/50 for emergency connections
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

The present invention offers systems and methods for effective multiple-hop routing, multicasting and media access control for vehicle group communications that employ directional wireless radio technology. Multi-beam optic-wireless media and streamlined operations provide low-overhead communications among vehicles. Systems and methods are provided to maintain a quasi-stationary group of neighboring vehicles, enable high-throughput on-demand switching among multiple vehicles, enable group coding in the vehicle group to achieve higher throughput, and enable dynamic adjustment of link to maintain desirable vehicle group. The proposed solution builds upon the conception of a MAC-free wireless operation and quasi-stationary vehicular switched network to achieve ultra-low-overhead and high-throughput vehicle communications.

Claims

1. ) A vehicular ad-hoc network (VANET), comprising:

a first vehicle having a plurality of antennas;

a first neighbor vehicle that transmits a data packet that is received by said first vehicle via a first antenna out of the plurality of antennas;

a second neighbor vehicle to receive said data packet send by said first vehicle via a second antenna out of the plurality of antennas;

said first vehicle further comprising a switching unit to transfer the data packet between said first and second antennas.

2. ) The VANET of claim 1, wherein communication between an antenna of a neighbor vehicle and an antenna out of the plurality of antennas of the first vehicle further comprises at least one directional radio link, and wherein the data packet further comprises metadata including an antenna ID, neighbor vehicle ID, initial location, hop count, sequence number, application attributes, and related information.

3. ) The VANET of claim 2, further comprising:

a logic unit to generate a link table for each antenna of said plurality of antennas on the first vehicle, said link table including records for each neighbor vehicle within communication range of said each antenna, and at least attributes such as bandwidth and link lifetime for each directional radio link with said each neighbor vehicle.

4. ) The VANET of claim 3, wherein the link table for each antenna is updated at a frequency that is a function of a relative speed of the first vehicle, and wherein records for neighbor vehicles that are not updated are purged after a set time.

5. ) The VANET of claim 2, wherein the first vehicle maintains a neighbor table comprising records for each directional radio link, said records including information about each antenna and the vehicle ID of the directional radio link.

6. ) The VANET of claim 5, wherein the records further comprise at least information pertaining to the link such as a MAC address and IP address of the antenna and the neighbor vehicle.

7. ) The VANET of claim 2, wherein the switching unit generates a Switched Packet List (SPL), said SPL comprising a source ID, sequence number for the data packet, acknowledgement status, and a cached copy of the data packet.

8. ) The VANET of claim 7, wherein the switching unit discards an incoming data packet if a record for said incoming data packet exists in the SPL.

9. ) The VANET of claim 7, wherein the switching unit discards an incoming data packet if the acknowledgement status for said incoming data packet is affirmative.

10. ) The VANET of claim 7, further comprising a switching table showing a status of all direct radio links between vehicles in the network, and a spanning tree comprising information on each outgoing link.

11. ) The VANET of claim 10, wherein the switching table comprises a source field, incoming field, and outgoing field, wherein the incoming and outgoing fields are obtained based on the outgoing links in the corresponding source spanning tree.

12. ) The VANET of claim 7, wherein the first vehicle forwards the data packet only to selected neighbors.

13. ) The VANET of claim 12, further comprising a Neighboring Information Table (NIT) comprising neighbors for the first vehicle and associated active links for each neighbor and neighbors for each neighbor.

14. ) The VANET of claim 13, further comprising a switching table showing status of incoming and outgoing direct radio links between the first vehicle and the plurality of neighbor vehicles, wherein the outgoing radio links are determined based on a comparison of immediate neighbors of the first vehicle and immediate neighbors of the neighbor vehicle.

15. ) The VANET of claim 1, further comprising:

a group coding manager configured to perform the following operations;

splitting the data packet into a plurality of blocks;

randomly selecting coefficients from a finite field;

taking a linear combination of the blocks with said coefficients; and

embedding the coefficients in the data packet to form a coded block;

wherein said coded block is transmitted via a plurality of intermediate vehicles to a destination vehicle whereupon the group coded block is decoded through a matrix inversion operation in a finite field.

16. ) A method for transmitting a data packet across a Vehicular Ad-hoc Network (VANET) having a plurality of vehicles, each of which having a plurality of directional antennas, the method comprising:

receiving at a first vehicle a data packet from a first neighbor vehicle via an incoming directional radio link from one of the plurality of directional antennas;

checking if the data packet is a duplicate data packet;

transferring the data packet to a second antenna of the plurality of antennas; and

forwarding the data packet to a second neighbor vehicle via a second outgoing radio link from said second antenna of the plurality of antennas.

17. ) The method of claim 16, wherein the data packet further comprises a header including a Source ID, Sequence Number, and Recipient Information for the data packet, the method further comprising:

generating a Switched Packet List (SPL), said SPL including the source ID, sequence number, acknowledgement status, and packet cache for each data packet;

determining a source and a scope of the data packet; and

adding the data packet to the SPL.

18. ) The method of claim 17, wherein the scope of the data packet includes any combination of a time-to-live of the packet or a maximum hop count of the data packet, the method further comprising discarding the data packet if the scope of the data packet is exceeded.

19. ) The method of claim 18, further comprising discarding the data packet if it is determined that the packet cache for the data packet already exists in the SPL.

20. ) The method of claim 19, further comprising:

awaiting for an acknowledgement from the second neighbor vehicle via the plurality of outgoing radio links;

retransmitting the data packet if said acknowledgement is not received; and

recording the acknowledgement status in the SPL when acknowledgement is received.

21. ) The method of claim 20, further comprising discarding the data packet from an outgoing link if acknowledgement has already been received.

22. ) The method of claim 21, further comprising:

generating a switching table showing status of all direct radio links between all vehicles in the network; and

generating a spanning tree comprising information on each outgoing link.

23. ) The method of claim 22, wherein the switching table comprises a source field, incoming field, and outgoing field;

and wherein the source field is the source of the spanning tree and incoming and outgoing fields are obtained by the outgoing links in the spanning tree.

24. ) The method of claim 21, further comprising forwarding the data packet only to selected neighbor vehicles.

25. ) The method of claim 24, further comprising generating a Neighboring Information Table (NIT) comprising immediate neighbors for the first vehicle and associated active links for each immediate neighbor and neighbors of each immediate neighbor.

26. ) The method of claim 25, further comprising generating a Switching Table showing status of incoming and outgoing direct radio links between the first vehicle and a plurality of neighbor vehicles, wherein the outgoing radio links are determined based on a comparison of the NIT of the first vehicle and the NIT of a second neighbor vehicle.

27. ) The method of claim 26, further comprising:

receiving a packet from the first neighbor vehicle;

receiving the NIT of said second neighbor vehicle via the direct radio link between the first vehicle and the second neighbor vehicle;

comparing said NIT of the second neighbor vehicle with the first vehicle'"'"'s own NIT; and

forwarding the packet only to the neighbors of the first vehicle out of the plurality of neighbor vehicles that are not present on the NIT of the second neighbor vehicle.

28. ) The method of claim 16, further comprising:

splitting the data packet into a plurality of blocks;

randomly selecting coefficients from a finite field;

taking a linear combination of the blocks with said coefficients; and

embedding the coefficients in the data packet to form a coded block.

29. ) The method of claim 28, further comprising transmitting said coded block to a neighbor vehicle.

30. ) The method of claim 29, further comprising decoding the coded block at the neighbor vehicle through a matrix inversion operation in a finite field

31. ) The method of claim 30, further comprising:

encoding blocks of a data packet at the first vehicle to form group coded data packet;

accumulating and relaying said group coded data packet at an intermediate vehicle; and

accumulating and decoding the group coded data packet at a destination vehicle.