Cross-layer optimization
Cross layer optimization is the escape from the pure waterfall-like concept of the OSI communications model with virtually strict boundaries between layers. The cross layer approach is just to transport feedback dynamically via the layer boundaries to enable the compensation for e.g. overload, latency or other mismatch of requirements and resources by any control input to another layer but that layer directly affected by the detected deficiency [1], [2].
Especially in information routing with concurrent demand for limited capacity of channels there may be a need for a concept of intervention to balance between e.g. the needs of intelligible speech transmission and of sufficiently dynamic control commands. Any fixed allocation of resources will lead to a mismatch under special conditions of operations. Any highly dynamic change of resource allocation might affect the intelligibility of voice or the steadiness of videos. However, as with other optimzing strategies, the algorithm consumes time as well [3].
Quality of Service (QoS)
Cross layer optimization shall contribute to an improvement of quality of services under various operational conditions. Such adaptive quality of service management is currently subject of various patent applications, as e.g. [4] The cross-layer control mechanism provides a feedback on concurrent quality information for the adaptive setting of control parameters. The control scheme applies
- the observed quality parameters
- a fuzzy logic based reasoning about applying the appropriate control strategy
- the statistically computed control input to parameter settings and mode switches
Resource efficiency =
The quality aspect is not the only approach to taylor the cross layer optimization strategy. The control adjusted to availability of limited resources is the first mandatory step to achieve at least a minimum level of quality. Respective studies have been performed and will continue <ref>http://www.nyman-workshop.org/2003/papers/Cross-Layer%20Optimization%20for%20Sensor%20Networks.pdfCite error: The opening <ref> tag is malformed or has a bad name (see the help page).