  In this paper, we study the joint resource allocation algorithm design for
downlink and uplink multicarrier transmission assisted by a shared user
equipment (UE)-side distributed antenna system (SUDAS). The proposed SUDAS
simultaneously utilizes licensed frequency bands and unlicensed frequency
bands, (e.g. millimeter wave bands), to enable a spatial multiplexing gain for
single-antenna UEs to improve energy efficiency and system throughput of $5$-th
generation (5G) outdoor-to-indoor communication. The design of the UE
selection, the time allocation to uplink and downlink, and the transceiver
processing matrix is formulated as a non-convex optimization problem for the
maximization of the end-to-end system energy efficiency (bits/Joule). The
proposed problem formulation takes into account minimum data rate requirements
for delay sensitive UEs and the circuit power consumption of all transceivers.
In order to design a tractable resource allocation algorithm, we first show
that the optimal transmitter precoding and receiver post-processing matrices
jointly diagonalize the end-to-end communication channel for both downlink and
uplink communication via SUDAS. Subsequently, the matrix optimization problem
is converted to an equivalent scalar optimization problem for multiple parallel
channels, which is solved by an asymptotically globally optimal iterative
algorithm. Besides, we propose a suboptimal algorithm which finds a locally
optimal solution of the non-convex optimization problem. Simulation results
illustrate that the proposed resource allocation algorithms for SUDAS achieve a
significant performance gain in terms of system energy efficiency and spectral
efficiency compared to conventional baseline systems by offering multiple
parallel data streams for single-antenna UEs.
