This work presents a distributed time-slot assignment algorithm which adopts TDMA as Medium Access Control, specially suited to support applications with strict delay, jitter, and throughput requirements characterized by convergecast traffic pattern in sensor networks. (e.g. wireless video surveillance sensor networks). The proposed algorithm has three characteristics: (1) every node is guaranteed a path to the base station for its data delivery. In the path, sufficient resource is reserved and weighted fairness can be achieved. (2) It uses cascading time-slot assignment and jitter minimization algorithm in each node to minimize jitter and end-to-end delay. (3) Nodes are only active during their scheduled slots and sleep otherwise. This offers energy saving by reducing idle listening and avoiding overhearing. The performance of the proposed algorithm is evaluated over simulations and analyzed theoretically in comparison with existing slot assignment algorithm. The results show that our algorithm provides lower end-to-end delay, jitter, and higher throughput. LOW-JITTER SLOT ASSIGNMENT ALGORITHM 811 Actually, a bound on delay variation in each hop from the source to destination is a bound on end-to-end delay as well [6]. Using one-hop delay and delay variation, we can calculate the end-to-end delay bound. Generally, jitter can be eliminated in two ways, increasing buffering space at the receiver or providing some mechanisms to minimize jitter. Increasing the amount of buffer space will add to the network cost and waste many network bandwidth. In this paper, we only consider how to devise a network protocol to minimize jitter. A good network protocol can improve the network performance and also reduce the amount of buffer space required by the network.Throughput is another important performance parameter in WSNs; owing to the funneling effect in WSNs [7], when data converge toward the sink, i.e. the base station, congestion is more likely to happen at sensors that receive more data than they can forward, when congestion happens, the network coverage and throughput fidelity are penalized. Therefore, congestion control is a critical issue in WSNs.Among the MAC protocol families, Time Division Multiple Access (TDMA) provides the best control of the trade-off between energy consumption and end-to-end delay [8]. Moreover, due to congestion and collision problems caused by CSMA protocol under high channel utilization, especially in multihop scenarios, jitter problem is very hard to solve in CSMA protocol [9]. In this paper, we use TDMA as medium access control.Current scheduling algorithms [7,8,[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] consider each node transmitting at least once during a TDMA frame. They are based on graph coloring scheme to avoid scheduling conflicts in twohop neighborhood, their goals are to maximize the slot spatial reuse for all nodes in a network to optimize throughput and avoid congestion [7,11,12,16] or to minimize TDMA frame length and delay by cascading slot assignment schem...
