User-Perceived Capacity: Theory, Computation, and Achievable Policies.

Area of Science:

• Wireless Communications
• Mobile Multimedia Services
• Quality of Experience

Background:

• User-perceived throughput is a key metric for mobile multimedia quality.
• Its performance limits and achievement strategies in wireless channels are not fully understood.

Purpose of the Study:

• To determine the achievable upper bound of user-perceived throughput (user-perceived capacity).
• To investigate methods for achieving this capacity in typical wireless channels.

Main Methods:

• Analysis of user-perceived capacity with Channel State Information at the Receiver (CSIR) only.
• Investigation of joint power and rate adaptation strategies with CSIR and Channel State Information at the Transmitter (CSIT).
• Application of a constrained Markov decision process (CMDP) for optimal policy computation.

Main Results:

• User-perceived capacity is significantly limited with CSIR alone.
• Joint CSIR and CSIT enable substantial improvements via power or rate adaptation.
• An optimal policy based on time, backlog, and channel gain thresholds was identified.

Conclusions:

• Achieving optimal user-perceived capacity necessitates joint power-rate adaptation enabled by CSIT.
• Power adaptation alone yields capacity equivalent to hard-delay-constrained capacity, utilizing diversity and channel inversion.