CLAPDAWN: cross layer architecture for protocol design in a wireless network

Abstract

Architecture plays a key role in overall success of the network protocol stack. It is essential to have robust architecture for the complex system having multiple cross protocol interactions. In the literature more emphasis is given to the cross layer protocol design than the cross layer architecture. Cross Layer Architectures [1, 2, 3, 4] available in literature are not addressing the problems of cross layer interaction at their depth. Our work focuses on cross layer architecture design that supports multiple cross layer protocols and cross layer interactions. It addresses the problem of lack of support for multiple cross layer interactions, feedback loops, a longer development time and smooth rollover from cross layer interaction. Our proposed Cross Layer Architecture for Protocol Design in A Wireless Network (CLAPDAWN) addresses these problems faced by many of the previously proposed architectures. We have worked on two critical problems of IEEE 802.15.4 based event driven wireless sensor networks: topology control problem and prioritized event handling problem. The IEEE 802.15.4 standard configures network nodes as Reduced Function Devices (RFD) and Full Function Devices (FFD). In randomly deployed wireless sensor networks, the problem of configuring the network nodes as RFD or FFD, maintaining the network functionality is a topology control problem. To solve this, we have proposed a multipoint relay based Connected Dominating Set (CDS) construction algorithm. In literature the topology control problem has been solved by centralized [5, 6, 6] and distributed [7, 8, 9] approaches. Dynamic nature of wireless sensor network makes centralized approaches less applicable and distributed approaches have the problem of overlapping and redundant nodes in the generated CDS. In our work we have proposed ROOT-Initiative (ROOT-I) and ROOT-Ik topology control algorithms to construct oneconnected and k-connected networks respectively. Proposed algorithms control the overlapping and redundant nodes in the network. They reduce the number of active nodes in the network that helps in extending the network lifetime. Further, the tradeoff between energy consumption and fault tolerability is analyzed for k-connectedness. Our results show that in randomly deployed dense networks, the algorithm has better approximation ratio with acceptable time and message complexity. The solution for the prioritized event handling is based on IEEE 802.15.4 MAC scheduling and channel access mechanism. IEEE 802.15.4 has Guaranteed Time Slot(GTS)mechanism for guaranteed data delivery. The GTS mechanism is not ufficient to provide solutions for the critical event handling problem. It has problems of reservation delay and limited number of GTS slots. To handle critical events in IEEE 802.15.4 based networks, we have proposed Explicit Prioritized Channel Access Protocol(EPCAP) and Implicit Prioritized Channel Access Protocol(IPCAP) mechanisms. The proposed mechanisms achieve higher delivery ratio for important events with smaller delay. The IPCAP and EPCAP are modeled using Markov chain and M/G/c queuing model respectively and tested through simulation. In ROOT-I and ROOT-Ik, network layer and MAC layer communicate to decide the node type (RFD or FFD) and in EPCAP and IPCAP prioritized events are handled by MAC based on information provided by application layer. As mentioned above CLAPDAWN is designed to support cross layer interactions in the system. To provide proof of concept for the CLAPDAWN we have modeled ROOT-I, ROOT-Ik, EPCAP and IPCAP as cross layer interactions in CLAPDAWN and we discuss how various components of CLAPDAWN communicate to implement these protocols. Furthermore to provide comparative analysis we have implemented ECLAIR [3] cross layer architecture with the CLAPDAWN.We have implemented the complex video streaming cross layer protocol [10] on both the architectures and derived the performance results. To make more rigorous comparison of both the architectures we have implemented conflicting cross layer interactions in the system. Our results show that CLAPDAWN has relatively better performance results than the ECLAIR. That shows CLAPDAWN provides better and stable platform for cross layer protocol development.