Increasing Code Rate of the Cooperative Relaying with Virtual OSTBC

In this paper we propose new schemes for increasing code rate of the cooperative relaying with virtual orthogonal space time block coding (OSTBC). The proposed schemes are used for creating virtual 4 × 1 multiple input–single output channel, and include one base station (BS) with two antennas, two relay stations (RS) each with a single antenna and one mobile station with a single antenna. One of the main disadvantages of the virtual OSTBC is its 1/2 code rate, so we propose new schemes with code rates 1, 4/5, 2/3 and 4/7 on the first hop, while the code rate on the second hop remains 1/ 2. The simulation results show that the proposed schemes maintain BER performance very close to the scheme with virtual OSTBC, e.g. in the case of BER value of 10⁻⁴ and Ricean channel parameter between BS and RSs of 10 dB the difference in the required signal to noise ratio between the proposed scheme with the greatest code rate and the virtual OSTBC is 0.25 dB, while for the proposed scheme with 4/7 code rate on the first hope this difference is only 0.05 dB.