Abstract
Cooperative communication achieves diversity through spatially separated cooperating nodes, which are battery powered in most applications. Therefore the energy consumption must be minimized without compromising the quality of service. In this context, we present a novel energy allocation scheme for multiple relay nodes that results in efficient cooperative multiple-input multiple-output (MIMO) communication. Considering channel path loss, the total transmission energy is distributed between the source and the relay nodes. The energy distribution ratio between the relay and direct link is optimized such that the quality of received signal is maintained with minimum total transmission energy consumption. We calculate the energy distribution ratio analytically and verified it through computer simulation. With the new energy allocation scheme, the system also obtains an increased channel capacity as compared to the cooperative scheme with conventional equal energy allocation and the non-cooperative scheme. Optimal relay positioning with the proposed energy allocation scheme is also explored to maximize the capacity.
Highlights
The ever increasing demands of spectrum efficiency and link reliability are challenged by the impairments in wireless channel as well as resource constraints
These challenges can be overcome by the use of multiple antennas at the transmitter and receiver, commonly known as multiple-input multiple-output (MIMO) scheme
MIMO systems provide the receiver with multiple versions of an information bearing signal that are subject to independent fading realizations
Summary
The ever increasing demands of spectrum efficiency and link reliability are challenged by the impairments in wireless channel as well as resource constraints. We propose a energy allocation scheme for multi-relay nodes cooperative communication with channel path loss. Where x(t) is the transmitted signal from the source node at time t with energy Es, hsd is the normalized channel gain from the source to the destination node with a corresponding path loss of PLsd, and nd(t) captures the effect of additive white Gaussian noise (AWGN) at the destination. Where T = LTs is the time slot or frame duration with L being the total number of symbols per frame and Ts the symbol period, hrmd is the normalized channel gain from the mth relay to destination node having a corresponding path loss of PLrmd, nd(t + mT) is the AWGN at the destination node, and km is the amplification factor at the mth relay that is used to remain within its power constraints.
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