Although the fourth generation is homogeneous under the IP umbrella, the participating 4G devices may have multiple interfaces and radios. A 4G device could bind each one of its interfaces to a distinct network, or use multiple interfaces to access a single network. With these features it will be possible to increase traffic bandwidth using link aggregation or execute hand-off without latency and instability, and maximize processing time available for functions such as data-error correction. Hence future routing protocols cannot assume the presence of static links between device interfaces and networks. They must deal with these heterogeneities under the IP layer and dynamic binding. A new class of challenges emerges, mainly in terms of QoS guarantees. So, how could the user achieve good acceptable performance when using several interfaces submitted to varying working conditions seen at several networks?
Mobile wireless devices often need to maintain data or voice communication across different access points and radio base stations. This process is known as hand-off Current cellular systems implement handoff over a single interface and only for phone calls. However, the next generation wireless system (4G) supports seamless handoff for data traffic and should be able to manage radio resources efficiently. VoIP continuity is another requirement in LTE especially when using the 3GPP IP Multimedia Service (IMS). In such a multi-radio environment, there is space to optimize bandwidth radio resources usage, signal quality and reduce information loss.
An important role for nontraditional routing approaches to play in improving future 4G communication systems is foreseen. The Wasp model has shown to be able to schedule tasks and reallocate resources, following a hierarchical and threshold based approach. Each wasp is stimulated to execute its task when its variable value becomes bellow a given threshold. We have seen this model being applied in the dynamic routing of vehicles, a prominent component of future 4G networks. Here, each vehicle is seen as a wasp with a threshold that waits before finding new optimized paths. When a node receives a request from two or more wasps with the same threshold, it then reserves the necessary resources and improves the routing path to the wasp with the highest hierarchy.
The wasp model may be used to resolve another important problem: that of interface selection. The individual force variation (F) is used for decision making, and to determine the best interface to use. This same wasp characteristic has also been associated to model signal strength, stability, efficiency and power consumption.
Since the binding between network and interface could be seen as a task, then wasp routing (Song, Hu, Tian & Xu, 2005) could also be a good approach to improve routing performance. Moreover, this scheme could also be used to manage and improve robustness by allocating messages to different networks when some paths may become unreachable.
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