US 2011/0211517 A1 · EFFICIENT AND RELIABLE MULTICAST OVER A Wi-Fi NETWORK

Abstract

A “Wi-Fi Multicaster” provides a practical and efficient Wi-Fi multicast system for environments having potentially large numbers of Wi-Fi clients. Significantly, the Wi-Fi Multicaster does not require any changes to the 802.11 protocol, or to the underlying Wi-Fi infrastructure. In various embodiments, the Wi-Fi Multicaster uses pseudo-broadcast, and augments it with destination control, association control and optional proactive FEC (forward error correction) to improve multicast performance. More specifically, the Wi-Fi Multicaster system converts multicast packets to targeted unicast transmissions. To minimize the amount of airtime consumed, the Wi-Fi Multicaster uses destination control in combination with various algorithms for association control. Further, in various embodiments, the Wi-Fi Multicaster includes an adaptive, proactive FEC scheme to reduce overall packet losses. Finally, to overcome the challenges posed by encryption protocols such as 802.1x, the Wi-Fi Multicaster uses a “virtual multicast interface” that allows clients to “share” a common key for each multicast.

Claims20

Dependent claims

A computer-readable medium having computer executable instructions stored therein for minimizing access point airtime consumed by multicast traffic in an 802.11-based Wi-Fi network, said instructions comprising causing a server computer to:

evaluate multicast subscription requests of a plurality of clients in wireless communication with one or more access points in the Wi-Fi network;
subscribe once to each unique multicast corresponding to each unique multicast subscription request on behalf of one or more multicast groups comprising one or more of the clients;
evaluate each client to perform an iterative “association control” process to assign each client to one of the access points, and sending the corresponding assignments to each client so that each client can associate with its assigned access point;
for each multicast group, performing a “destination control” process for identifying a single client having a lowest transmission rate with its assigned access point, and designating each such client as a “target client”;
converting all subscribed multicasts to unicasts;
and
providing the unicasts to each access point having any clients subscribed to the corresponding multicast, and directing the access points to transmit the unicasts only to corresponding target clients.

4 more elements

A method for minimizing access point airtime consumed by multicast traffic in an 802.11-based Wi-Fi network, comprising steps for:

providing at least one server in communication with a plurality of wireless access points in an 802.11-based Wi-Fi network;
providing a plurality of clients capable of wireless communication with one or more of the access points;
on each client, intercepting each client generated multicast subscription request and sending each intercepted request to the at least one server via an initial access point associated with each client;
on the at least one server, subscribing to each unique multicast subscription request on behalf of a multicast group comprising one or more of the clients;
on the at least one server, performing an iterative “association control” process to assign each client to one of the access points, and sending the corresponding access point assignments to each client so that each client can associate with its assigned access point, said assignments operating to minimize airtime consumed by each access point;
on the at least one server, for each multicast group performing a “destination control” process to identify a single client having a lowest transmission rate with its assigned access point, and designating each such client as a “target client”;
on the at least one server, converting each multicast to a unicast and providing each resulting unicast to each access point having assigned clients subscribed to the corresponding multicast group, and wirelessly transmitting each such unicast to each corresponding target client;
on each target client for each multicast group, directly receiving each corresponding unicast transmission;
on each other client for each multicast group, receiving packets of each corresponding unicast transmission intended for target clients by listening to those transmissions in a “promiscuous mode”;
and
on all clients, decoding received unicasts, converting the decoded unicasts to multicasts and providing local playback of the multicasts.

8 more elements

A system for minimizing access point airtime consumed by multicast traffic in a wireless network, comprising:

a subscription device on a server for evaluating multicast subscription requests of a plurality of clients in wireless communication with one or more access points in the wireless network, said subscription device acting to subscribe once to each unique multicast corresponding to each unique multicast subscription request on behalf of one or more multicast groups comprising one or more of the clients;
an association control device on the server for evaluating each client to perform an iterative “association control” process to assign each client to one of the access points, and sending the corresponding access point assignments to each client so that each client can associate with its assigned access point;
a destination control device on the server for identifying a single client, for each multicast group, having a lowest transmission rate with its assigned access point, and designating each such client as a “target client”;
a multicast transmission device on the server for converting all multicasts to unicasts, providing the unicasts to one or more of the access points, and directing the access points to transmit the unicasts only to corresponding target clients;
and
a decoding device on each client, for each multicast group, for receiving the corresponding unicast transmissions, decoding the received unicasts using a shared security session key of the corresponding target client, and converting the decoded unicasts to multicasts for local playback on each client.

3 more elements

Dependencies are inferred from the claim text.

EFFICIENT AND RELIABLE MULTICAST OVER A Wi-Fi NETWORK

Life of this patent

EFFICIENT AND RELIABLE MULTICAST OVER A Wi-Fi NETWORK

Life of this patent

Abstract

Claims20