Wireless routing selection system and method
View Patent ↗A technique involves untethered access points (UAPs) that can broadcast estimated transmission time (ETT) that represents an estimated time it would take for a packet to be transmitted from the first UAP to an AP that is wire coupled to a network. The proposed system can offer, among other advantages, accurate ETT values for use by UAPs of a wireless network.
1. A method comprising:
receiving, at a current wireless node, an estimated transmission time (ETT) from each of a plurality of other wireless nodes that are within a range of the current wireless node, wherein each said ETT is a next-hop-to-destination-path ETT (ETTp) associated with one of said other wireless nodes, wherein each said ETTp is a function of a link ETT (ETTI), another ETTp and a node transition time (NTT) of one of said other wireless nodes;
at the current wireless node, measuring for each of said other wireless nodes an ETTI between the current wireless node and a corresponding one of said other wireless nodes;
at the current wireless node, adding for each of said other wireless nodes an ETTI to a corresponding ETTp to determine a node-specific path metric for a corresponding one of said other wireless nodes;
at the current wireless node, selecting a next hop based on the determined node-specific path metrics;
at the current wireless node, calculating an advertised ETTp for the current wireless node, based on at least one of the measured ETTI's, a corresponding at least one of the received ETTp's and a calculated NTT for the current wireless node; and
broadcasting the advertised ETTp from the current wireless node to a second wireless node.
2. The method of claim 1 , wherein measuring an ETTI comprises:
placing a packet on an egress queue;
taking a first timestamp;
receiving acknowledgement that the packet was transmitted;
taking a second timestamp;
finding the difference between the first timestamp and the second timestamp.
3. The method of claim 2 , wherein finding the difference between the first timestamp and the second timestamp includes taking an exponentially decaying average.
4. The method of claim 1 , wherein the calculating the advertised ETTp comprises:
receiving a packet on an ingress interface;
taking a first timestamp;
forwarding the packet to an appropriate egress interface;
taking a second timestamp;
finding the difference between the first timestamp and the second timestamp.
5. The method of claim 4 , wherein finding the difference between the first timestamp and the second timestamp includes taking an exponentially decaying average.