In a relay channel, between the sender X and the the receiver Y lies at least one relay. Generally, the relay can both transmit its own information and help forwarding other sources’ information. This summary considers the latter case, i.e., the relay intends solely to help the receiver. The relay and the transmitter cooperate to resolve the receiver’s uncertainty. Due to the presence of relay,...

In this paper, a dual-hop relay based on channel state is studied. In the conventional relay scheme, a relay uses the same modulation method without reference to channel state. But, a relay uses an adaptive modulation method with reference to channel state. If the channel state is poor, a relay eliminates latter 2 bits and uses Quadrature Phase Shift Keying (QPSK) modulation. If channel state i...

The performance of cooperative network can be increased by using relay selection technique. Therefore, interest in relay selection is sloping upward. We proposed two new relay selection schemes based on fuzzy logic for dual hop cooperative communication. These relay selection schemes require SNR (signal to noise ratio), cooperative gain and channel gain as input fuzzy parameters for selection o...

We derive the capacity of the state-dependent half-duplex relay channel without source-destination link. The output of the state-dependent half-duplex relay channel depends on the randomly varying channel states of the source-relay and relay-destination links, which are known causally at all three nodes. For this channel, we prove a converse and show the achievability of the capacity based on a...

In this paper, a class of state-dependent relay channel with orthogonal channels from the source to the relay and from the source and the relay to the destination is studied. The two orthogonal channels are corrupted by two independent channel states SR and SD, respectively, which are known to both the source and the relay. The lower bounds on the capacity are established for the channel either...

A discrete memoryless half-duplex relay channel is constructed from a broadcast channel from the source to the relay and destination and a multiple access channel from the source and relay to the destination. When the relay listens, the channel operates in the broadcast mode. The channel switches to the multiple access mode when the relay transmits. If the broadcast component channel is physica...

In this paper, our objective is maximizing total sum-rate subject to power constraints on total relay transmit power or individual relay powers, for amplify-and-forward single-antenna relay-based wireless communication networks. We derive a closed-form solution for the total power constraint optimization problem and show that the individual relay power constraints optimization problem is a quad...

We consider a discrete memoryless relay channel, where both relay and destination may have an incorrect estimation of the channel. This estimation error is modeled with mismatched decoders. In this paper, we provide a lower-bound on the mismatch capacity of the relay channel. Moreover, we prove that this lower-bound is indeed the exact capacity for the degraded relay channel when random coding ...

This paper presents an optimum amplifying relay matrix based on minimum mean square error (MMSE) criteria for the cooperative distributed wireless relay networks under channel uncertainty and total power constraint at the relay nodes. A one-source-one-destination pair node and N relay nodes are considered, which can be extended for a general case. All relays are assumed to exchange their receiv...