Abstract
A novel scheme for two-hop relaying defined as space division duplex (SDD) relaying is proposed. In SDD relaying, multiple antenna beamforming techniques are applied at the intermediate relay station (RS) in order to separate downlink and uplink signals of a bi-directional two-hop communication between two nodes, namely, S1 and S2. For conventional amplify-and-forward two-hop relaying, there appears a loss in spectral efficiency due to the fact that the RS cannot receive and transmit simultaneously on the same channel resource. In SDD relaying, this loss in spectral efficiency is circumvented by giving up the strict separation of downlink and uplink signals by either time division duplex or frequency division duplex. Two novel concepts for the derivation of the linear beamforming filters at the RS are proposed; they can be designed either by a three-step or a one-step concept. In SDD relaying, receive signals at S1 are interfered by transmit signals of S1, and receive signals at S2 are interfered by transmit signals of S2. An efficient method in order to combat this kind of interference is proposed in this paper. Furthermore, it is shown how the overall spectral efficiency of SDD relaying can be improved if the channels from S1 and S2 to the RS have different qualities.
Highlights
There exists much ongoing work in the promising research field of two-hop relaying [1, 2]
The bit error rate (BER) performance strongly depends on the applied modulation and coding schemes which have to be individually adapted to the current channel conditions and the quality of service (QOS) requirements of the transmission
In space division duplex (SDD) relaying, downlink and uplink signals are separated by applying transceive filters at the relay station (RS) which can be designed by a one-step or a three-step concept
Summary
There exists much ongoing work in the promising research field of two-hop relaying [1, 2]. Most two-hop relaying schemes assume a strict separation of downlink and uplink signals by either TDD or FDD. These schemes are defined as one-way relaying schemes since downlink and uplink can be regarded independently. If downlink and uplink signals are separated by either TDD or FDD, the number of required channel resources is doubled compared to a single-hop communication. Regarding the spectral efficiency of two-hop relaying, this leads to a trade-off between the improved receive signal quality due to the reduced overall pathloss between S1 and S2 and the increase in required channel resources due to the two-hop approach. There exist schemes which relax the strict separation of downlink and uplink by TDD or FDD which are promising and in the focus of this work
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
