Real-time communication in multi-hop networks

A Distributed Route-Selection Scheme for Establishing Real-Time Channels

“…As in [3,5,8], the generation of real-timP messages is assumed to be governed by the linear-bounded model that is characterized by three parameters: maximum message size Smax (bytes), maximum message rate Rmax (messages/second), and maximum burst size Bmax (messages). In the linear bounded model, there are two restrictions on each arrival: (1) the number of messages generated in any time interval of length t does not exceed Bmax + tRmax; (2) the length of each message does not exceed Smax· Based on this message arrival model, the authors of [5] proposed a scheme to estimate the worstcase delay on each link and a run-time scheduling algorithm for real-time messages. By adding the worst-case delays of all links that a channel runs through, one can calculate the worst-case end-to-end delivery delay.…”

“…This end-to-end delay is then compared against the user-specified end-to-end delay bound for the requested channel and the system can decide whether to accept/reject the corresponding real-time channel-establishment request. Using the delay-estimation method in [5] and a Bellman-Ford-like algorithm, we will in this paper develop a scheme to find a qualified route for each channel-establishment request.…”

“…The goal of the algorithm in [5] is to compute the minimum worst-case delay on a link for a new real-time channel to be added without compromising the performance guarantee of any of the existing channels on the link. Let { Mi = ( Ci, Pi, di), i = 1, ... , k} be the set of k existing channels on a link, where C; is the maximum time required to transmit a message of channel Mi on the link, Pi = I:r,in = If-is the minimum message inter-arrival time in M;, and di is the maximum delay assignedmt~ M; on this link, or link {delay) deadline.…”

“…Let { Mi = ( Ci, Pi, di), i = 1, ... , k} be the set of k existing channels on a link, where C; is the maximum time required to transmit a message of channel Mi on the link, Pi = I:r,in = If-is the minimum message inter-arrival time in M;, and di is the maximum delay assignedmt~ M; on this link, or link {delay) deadline. Note that the inequality di :<; Pi must hold for the algorithm in [5] to work correctly. Given a new channel Mk+1 = (Ck+l,Pk+!)…”

“…phase is of prime importance to the realization of a real-time channel, and during this phase, the system has to select a route between the source and destination of the channel along which sufficient resources can be reserved to meet the user-specified delay and buffer requirements. Although several channel-establishment schemes have been proposed in the literature [2,4,5,7], very few oft hem have addressed explicitly the issue of selecting a route between the source and destination of a channel, despite its importance to the channelestablishment phase.…”