Efficient Cooperative Relaying in UMTS-WiMAX- WLAN Overlaid Heterogeneous Networks

Future wireless communication is expected to integrate collocated different radio access technologies together to meet wide expectation (multiple services) from users and to support mobility. The key requirements in this multiple radio access technology are to meet the Quality of Service (QoS) requirement of the user based on the service type, reduce energy consumption for the particular service and to improve spectral efficiency of the individual networks. Spectral efficiency and energy consumption are crucial factors that can be expected to achieve using cooperative relaying. In this paper cooperative relaying is considered in Internet Multimedia Subsystem (IMS) based integrated UMTS-WiMAXWLAN overlaid networks. Source, destination and relay nodes are considered as multiple radio access nodes. Each radio networks use different frequency and bandwidth for communication and consumes different energy (energy required for transmission depends on frequency of transmission). In this paper distance based path-loss model is considered and multiple radio access nodes that can decode source message with the targeted QoS are considered as relay nodes. In the proposed algorithm each relay node selects efficient radio network mode (radio channel) for relaying source message to the destination from the available networks that satisfies QoS requirements of the particular service. Fully distributed Boltzmann-Gibb’s learning algorithm is used for selecting efficient radio mode in real time environment. The relay node having high channel gain to destination and consuming less energy (depends on selected radio mode frequency and its bandwidth) to transmit message is selected as optimal relay node in the proposed algorithm. The proposed optimal relay node with efficient radio mode communication is compared with optimal relay with random radio mode communication, random relay communication and direct communication. Voice and video applications are considered between source and destination individually. The proposed scheme provides better QoS (For voiceLess jitter, packet end-to-end delay, Mean Opinion Score (MoS) network loss, retransmission attempt, average transmit power, increased MoS value; For videoless packet delay variation, packet endtoend delay, retransmission attempts, average transmit power and increased throughput) for both the services compared with other schemes. In the proposed scheme relay node uses the spectrum of the less loaded network that improves the spectral efficiency of the network.