A Review of Protocol Implementations and Energy Efficient Cross-Layer Design for Wireless Body Area Networks <s> Merging of Adjacent Layers <s> Contrary to present conjectures, our medium access control (MAC) based performance studies revealed that battery capacity may not be used as the sole means for achieving energy-based fairness and system longevity for wireless mobile multi-hop ad hoc and sensor networks. Moreover, energy conservation may be attained only if valuable MAC (and PHY) input is passed to the network layer. Hence, we propose two schemes, the objective of which is to enhance the operation of existing power-based multi-path routing protocols via cross-layer designs and optimal load assignments. Our proposed schemes, namely, energy-constrained path selection (ECPS) and energy-efficient load assignment (E2LA), employ probabilistic dynamic programming techniques and utilize cross-layer interactions between the network and MAC layers. To the best of the authors' knowledge, this is the first time that MAC-originated information is used as the basis for achieving energy-efficient routing. <s> BIB001 </s> A Review of Protocol Implementations and Energy Efficient Cross-Layer Design for Wireless Body Area Networks <s> Merging of Adjacent Layers <s> Wireless sensor networks represent a key technology enabler for enhanced health care and assisted living systems. Recent standardization eorts to ensure compatibility among sensor network systems sold by dierent vendors have produced the IEEE 802.15.4 standard, which specifies the MAC and physical layer behavior. This standard has certain draw-backs: it supports only single-hop communication; it does not mitigate the hidden terminal problem; and it does not coordinate node sleeping patterns. The IEEE 802.15.4 standard design philosophy assumes that higher layer mechanisms will take care of any added functionality. Building on IEEE 802.15.4, this paper proposes TImezone COordinated Sleep Scheduling (TICOSS), a mechanism inspired by MERLIN [2] that provides multi-hop support over 802.15.4 through the division of the network into timezones. TICOSS is cross-layer in nature, as it closely coordinates MAC and routing layer behavior. The main contributions of TICOSS are threefold: (1) it allows nodes to alternate periods of activity and periods of inactivity to save energy; (2) it mitigates packet collisions due to hidden terminals belonging to nearby star networks; (3) it provides shortest path routing for packets from a node to the closest gateway. Simulation experiments confirm that augmenting IEEE 802.15.4 networks with TICOSS doubles the operational lifetime for high trac scenarios. TICOSS has also been implemented on the Phillips AquisGrain modules for testing and eventual deployment in assisted living systems. <s> BIB002
Although there are numerous cross-layer schemes that couple, for example, the MAC and physical layers BIB001 BIB002 , these schemes still retain the traditional stack architecture. Efficiencies can be gained by creating a new super-layer that effectively merges the functions of both layers without the traditional overhead of two entirely separate layers. This union of the two layers services would not require new stack interfaces but rely on the existing interfaces to the rest of the protocol stack.