Pseudo-unicasting data in multihop radio communications
Original Publication Date: 2002-Sep-01
Included in the Prior Art Database: 2003-Jul-23
Hui Li: AUTHOR [+3]
1. Data relaying
Information / Kommunikation
Pseudo-unicasting data in multihopradio communications
2. Route repair
Idee: Hui Li, Nürnberg;
Egon Schulz, München;Dan Yu, München
1. Data relaying
Figure 1 shows mobile nodes MN in an ad-hoc net-work. In Figure 1, after the route discovery, MN-Sselects MN-S « MN1 « MN2 « MN-D as theroute to the destination MN-D. MN1 should be in-formed that it can reach the destination MN-Dthrough the neighbors MN3 and MN4 as well. NowMN1 transmits DLC data packets in the followingsteps:
Step 1: MN1 unicasts DLC packets to MN2, but itinforms MN3 and MN4 to decode and store the DLCpackets at the same time. Only MN2 acknowledgesMN1 for the correctly received DLC packets, whileMN3 and MN4 do not need to send acknowledge-ments to MN1 and the DLC packets to MN-D, re-spectively.
Step 2: MN1 checks the acknowledgements fromMN2. If all DLC packets belonging to an IP packetare correctly received by MN2, MN1 removes the IPpacket from its buffer and sends the next DLC packetwith an indication for MN3 and MN4 to clean theirstorage. When MN3 and MN4 get this message, theyremove all DLC packets from their buffers.
Step 3: If MN1 senses that the radio link to MN2 isbroken, MN1 immediately sends an acknowledge-ment request to MN3 and MN4. After decoding theacknowledgement request, MN3 and MN4 will in-form MN1 which DLC packets have been received.
Figure 1 Pseudo-unicasting DLC packets betweenMN-1 and MN-2, MN-3, MN-4
In Figure 2, MN2 and MN4 move to the outside ofthe reach of MN1. After the route to MN-D, i.e. MN-S « MN1 « MN2 « MN-D, is broken, MN1 re-quests acknowledgements from MN3 and MN4.MN4 can not receive the request, while MN3 re-ceives the request and sends an acknowledgement toMN1. Then MN-...