Full-duplex transceiver for future cellular network: A smart antenna approach

Abstract

In this paper, we propose a transceiver architecture for full-duplex (FD) eNodeB (eNB) and FD user equipment (UE) transceiver. For FD communication,.i.e., simultaneous in-band uplink and downlink operation, same subcarriers can be allocated to UE in both uplink and downlink. Hence, contrary to traditional LTE, we propose using single-carrier frequency division multiple accesses (SC-FDMA) for downlink along with the conventional method of using it for uplink. The use of multiple antennas at eNB and singular value decomposition (SVD) in the downlink allows multiple users (MU) to operate on the same set of subcarriers. In the uplink, successive interference cancellation with optimal ordering (SSIC-OO) algorithm is used to decouple signals of UEs operating in the same set of subcarriers. A smart antenna approach is adopted which prevents interference, in downlink of a UE, from uplink signals of other UEs sharing same subcarriers. The approach includes using multiple antennas at UEs to form directed beams towards eNode and nulls towards other UEs. The proposed architecture results in significant improvement of the overall spectrum efficiency per cell of the cellular network.

Analysis of Full-Duplex Downlink Using Diversity Gain

“…In the uplink, successive interference cancellation with optimal ordering (SSIC-OO) algorithm [4] is used at the eNB to segregate signals of UEs sharing the same subcarriers. In [4], a smart antenna approach is deployed to avoid the CCI at downlink of UEs. Here, the paper concentrates on the downlink operation and to avoid CCI at downlink of a UE, diversity combining technique is used to minimize interference from the uplink signals of other co-existing UEs.…”

“…The signal is then subjected to the subcarrier deallocation and after simplifications [4], [5], we get:…”

“…However, the use of the same subcarriers for both uplink and downlink results in co-channel interference (CCI) in downlink of a UE from uplink signals of other UEs operating in the same subcarriers. The prior work [4], considers deploying the smart antenna technique at the UEs with highly spatially correlated multiple antennas. In this work, a converse scenario is considered with a highly scattered environment which prevents the use of the method proposed in [4] to mitigate the CCI.…”

“…The prior work [4], considers deploying the smart antenna technique at the UEs with highly spatially correlated multiple antennas. In this work, a converse scenario is considered with a highly scattered environment which prevents the use of the method proposed in [4] to mitigate the CCI. Hence, here the use of diversity gain at the UEs is analyzed to mitigate the effect of CCI and allowing the UEs to share the same spectrum resources.…”

“…For FD operation, same subcarriers can be allocated to a UE for uplink and downlink. Hence, the use of SC-FDMA for both uplink and downlink is proposed [4], due to its advantages over OFDMA in terms of bit error rate (BER) performance and energy efficiency [5].…”