HSC welcomes all external visitors to this site, especially students and members of the academic community. Please use the comments box at the bottom of each page to record any comments or suggestions for improvement.
Link Adaptation
The Basic Idea
Link adaptation is the widely used concept in wireless communication which pertains to the adaptation of the transmission parameters in accordance with the varying link condition. The parameter that needs to be dynamically adapted are modulation, coding, power and other signaling parameters. The link parameters that affects the link conditions are path loss, fading, interference etc. Link adaptation involves the concept of error detection and correction
The Need
Wireless Spectrum is very costly. Its extremely important to utilize the spectrum efficiently ensuring throughput, reliability while guaranteeing end users QoS or SLA.A system designed to meet the worst case yields poor performance. The basic idea of link adaptation is to operate a link as efficiently as possible in the prevailing channel conditions by adapting certain transmission parameter. The trade off lies between robustness and spectrum efficiency. The benefits of link adaptation results in net increase in link capacity by adapting the system to make the most out of time varying channel. The choice of link adaptation to be used depends on various parameters including the QoS requirement of the traffic, channel conditions, trans-receiver capability, air interface.
The Protocol Stack
Figure below shows the protocol stack depicting the link adaptation
The Data Link control protocol plays key role in enabling the functionalities of link adaptation.
Link Adaptation Techniques
Broadly we can classify link adaptation in two ways
Forward error correction?
Automatic Repeat Request
Hybrid ARQ
Adaptive coding and modulation?
Categories: Wireless
Comments
