In this paper, we study two-hop communication protocols where several relay terminals assist in the communication between two terminals. The terminals operate in halfduplex mode, hence the transmission of one information symbol from the source terminal to the destination terminal occupies two channel uses. This leads to a loss in spectral efficiency
due to the per-log factor one-half in corresponding capacity expressions. In this paper, we propose to apply two-path and two-way protocols to multi-relay networks. These relay protocols avoid the pre-log factor one-half. The communication channels between source and relays and between the relays and destination are assumed to be Rayleigh flat fading. The
performance of the network is investigated for perfect and estimated channel and for decodeand- forward scheme. The performance is measured in terms of bit error rate. Moreover the outage probability is evaluated when one relay is used and is compared with that one for multi-relay system. Channel estimation is performed using least square algorithm. The
performance of the channel estimation algorithm is measured in terms of the mean square error of estimation.