REAL-TIME WIRELESS MULTICAST ROUTER

摘要

This invention generally relates to Low-power and Lossy Wireless Networks. The proposed solution takes advantage of the fact that retry mechanism and back-off mechanism are already present in trickle-based algorithms. This way, it is possible to disable the equivalent features present at the MAC level which are the main causes of the large maxima of the fluctuating end-to-end delay. Also, it has been done away with the additional waiting time which comes from the packet waiting in the buffer in the MAC. Therefore, it has been provided a real-time layer with a limited size buffer able to allocate a deadline to a multicast packet and to select packets for transmission or rejection on the basis of the packet deadline. This way, it is kept a tighter hold on the rejection and waiting of the packets.

主权项

1. A router for controlling multicast transmission in a low-power wireless network, the router comprising:
a trickle-based multicast protocol layer, MPL, interface adapted to create a multicast packet; and, a Medium Access Control, MAC, layer interface comprising a MAC layer queue adapted to receive a plurality of multicast packets, the MAC layer interface being adapted to transmit, over the network, the multicast packets stored in the MAC layer queue in their order of arrival, the MAC layer interface further comprising a MAC retry mechanism associated with a backoff mechanism and adapted to retransmit unsuccessfully transmitted multicast packets; characterised in that the router further comprises: a real-time layer, RTL, interface coupled to the MPL layer interface and the MAC layer interface, and adapted to:
disable the MAC layer queue, the MAC retry mechanism and the MAC backoff mechanism;receive the multicast packet from the MPL layer interface; and,either,
alter the multicast packet by adding a deadline by which said altered multicast packet is to be discarded by a router of the network where said deadline has already passed; or,discard said multicast packet where said deadline has already passed; where said multicast packet has been altered, the RTL interface is further adapted to:
forward said altered multicast packet to the MAC layer interface when the latter is ready to transmit; and,put said altered multicast packet on hold when the MAC layer is not ready to transmit; wherein the RTL interface is adapted to forward or put on hold said altered multicast packet based on said deadline.