Space time frequency coding for dual polarization MIMO in hybrid mobile satellite system

The hybrid mobile satellite system operating in a single frequency network (SFN) mode is increasingly becoming attractive. The combination of satellite component (SC) and terrestrial component (TC) promises a better quality of service (QoS). Multimedia broadcast and multicast services (MBMS) are expected to be prevailed in this kind of system. Several space frequency (SF) or space time (ST) codes have been proposed to enhance the system performance due to the lack of reverse link and omni-directional transmission. However, they mostly consider the system with only one SC and one TC and fail to make full use of available diversities. This paper presents a novel way to realize the dual polarization multiple input multiple output (MIMO) transmission by using the space time frequency (STF) code. The theoretical analysis and simulations indicate that the application of STF code can improve the system performance dramatically. A higher diversity gain can be achieved due to the cooperative transmission of SC and TC, while the coding gain can be enhanced by the reusing of STF code between SCs or TCs. Even if some of the links are lost, it can still work properly and benefit from the STF code. The relative relay can result in a degradation up to 0.5 dB in the coding gain.