# A QoS Optimization Approach in Cognitive Body Area Networks for Healthcare Applications
## 2 Related Works
This could give rise to a competition for the available spectrum, i.e., channels. Hence, there must be mechanisms for channel allocation and sharing in such a way to satisfy the traffic and throughput requirements. Another constraint for operating in such a heterogeneous environment is interference. To avoid interference, some power control mechanism must be incorporated in the WBANs. In [18], the authors have presented a channel sharing protocol for WBANs, but only for medical applications. Therefore, such an approach lacks information about spectrum sharing among networks to facilitate their co-existence in the available spectrum. In [19], the authors investigated channel allocation schemes in generalfor a wireless sensor network (WSN) based on game theory. The authors considered a general WSN for investigating the behavior of their algorithm, showing that it exploits the network knowledge to reduce interference and improve overall WSN performance. Such an approach could lead to additional studies for WBANs. The authors in [20] proposed a multichannel MAC coordination framework called decentralized time synchronized channel swapping. The proposed protocol combines the benefits of decentralized time division multiple access and spontaneous alignment of nodes' time slots across channels and flexible time synchronization by instantaneous adoption of available slots. The authors compared their proposed MAC protocol for channel swapping with time synchronous channel hopping and efficient multichannel MAC protocols. Simulation and experimental results show that the proposed approach leads to a significant reduction in convergence time and provides higher network throughput with and without the presence of interference. However, the proposed scheme has been applied to ad hoc wireless networks and the behavior of the protocol in WSNs and WBANs is yet to be investigated. In [21], the authors describe channel estimation and power control schemes for WBANs. The authors claim that their proposed algorithm can save up to 25% of energy as compared to a fixed transmission power scheme. The proposed algorithm has been investigated in IEEE 802.15.6 beacon mode [22] with a single hop star topology. In [23], the author investigated transmission power assignment schemes and energy minimization techniques for WBANs. The author used two strategies to assign transmission powers to the on-body sensor nodes; with or without body posture state information. He studied his power optimization approach in a single hop transmission link. However, the proposed transmission power assignment algorithms presented in [21; 23] have not been investigated nor evaluated for the specific off-body communication links used in WBANs and their potential impact in a two-hop star topology. The person or patient who is being monitored cannot always remain stationary, i.e., laying in bed or sitting. Hence, there is a need for mobility algorithms to be implemented into the WBAN so that seamless communication occurs when the nodes are mobile and they move from one access point to another access point. In [24], the authors presented a seamless mobility and handover scheme for WSNs taking into account the sensor mobility from one access point to another. This approach is used as the basis for our own handover implementation described in Section 3.4. The authors in [25] have presented an optimization algorithm for the design of WBANs. The approach is based on a heuristic model and an ant colony optimization method. The authors proposed these algorithms for WBAN design considerations, i.e., network topology and routing, taking into account the variable data rates from individual sensor nodes. The experimental results are promising in terms of quality and computational time as compared to a commercial optimization problem solver. However, the algorithm needs further investigation to improve its performance. In [26] a robust optimization approach to tackle traffic uncertainty in network design problems was proposed.