22-01-2013, 02:30 PM
Multiuser OFDM with Adaptive Subcarrier, Bit and Power Allocation
Multiuser OFDM.ppt (Size: 458 KB / Downloads: 53)
Motivation
Orthogonal Frequency Division Multiplexing (OFDM) provides a transmission scheme to avoid frequency selective fading in a wide band wireless communications.
How to allocate different user to use different subcarriers with adaptive optimal bit (modulation) and power becomes an interesting problem in a wireless multiuser environment.
Multiuser Subcarrier and Bit Allocation Algorithm
As users can not share the same subcarrier, this dependency makes the greedy algorithm a non-optimal solution.
Some relaxations on previous problem have to be made.
Multiuser Adaptive OFDM (MAO)
Satisfy the constraint:
Using the optimal method to decide the proper carrier for a specific user.
Then use the single user bits allocation algorithm to satisfy its data rate requiremet.
Note that
Conclusions
The proposed MAO outperforms than the conventional MA techniques in an OFDM system.
Quantify the performance improvement in terms of SNR, BER and Outage Pr.