We consider the uplink of two mobile stations with the help of one common relay. Recently, joint network-channel coding based on LDPC codes was proposed for this setup where the channel codes at the mobile stations and the network code at the relay form one distributed LDPC code. This approach allows to gain diversity with a higher rate compared to a relay system without network coding. We propose a practical joint network-channel code that follows the structure of the WiMax IEEE 802.16e LDPC code, and that benefits from efficient linear time encoding and reduced storage requirements. We show how to use a modified high girth code at the relay that allows to gain diversity. Further, we compare two decoding methods of the distributed code at the destination. Simulation results for an example with noisy block fading channels against reference systems demonstrate the advantage of the proposed design.
['Lena Chebli', 'Christoph Hausl', 'Georg Zeitler', 'Ralf Koetter']
Cooperative Uplink of Two Mobile Stations with Network Coding Based on the WiMax LDPC Code