3 research outputs found
Joint Antenna Array Mode Selection and User Assignment for Full-Duplex MU-MISO Systems
This paper considers a full-duplex (FD) multiuser multiple-input
single-output system where a base station simultaneously serves both uplink
(UL) and downlink (DL) users on the same time-frequency resource. The crucial
barriers in implementing FD systems reside in the residual self-interference
and co-channel interference. To accelerate the use of FD radio in future
wireless networks, we aim at managing the network interference more effectively
by jointly designing the selection of half-array antenna modes (in the transmit
or receive mode) at the BS with time phases and user assignments. The first
problem of interest is to maximize the overall sum rate subject to
quality-of-service requirements, which is formulated as a highly non-concave
utility function followed by non-convex constraints. To address the design
problem, we propose an iterative low-complexity algorithm by developing new
inner approximations, and its convergence to a stationary point is guaranteed.
To provide more insights into the solution of the proposed design, a general
max-min rate optimization is further considered to maximize the minimum
per-user rate while satisfying a given ratio between UL and DL rates.
Furthermore, a robust algorithm is devised to verify that the proposed scheme
works well under channel uncertainty. Simulation results demonstrate that the
proposed algorithms exhibit fast convergence and substantially outperform
existing schemes.Comment: Accepted for publication in IEEE Transactions on Wireless
Communication
A Novel Heap-based Pilot Assignment for Full Duplex Cell-Free Massive MIMO with Zero-Forcing
This paper investigates the combined benefits of full-duplex (FD) and
cell-free massive multiple-input multipleoutput (CF-mMIMO), where a large
number of distributed access points (APs) having FD capability simultaneously
serve numerous uplink and downlink user equipments (UEs) on the same
time-frequency resources. To enable the incorporation of FD technology in
CF-mMIMO systems, we propose a novel heapbased pilot assignment algorithm,
which not only can mitigate the effects of pilot contamination but also reduce
the involved computational complexity. Then, we formulate a robust design
problem for spectral efficiency (SE) maximization in which the power control
and AP-UE association are jointly optimized, resulting in a difficult
mixed-integer nonconvex programming. To solve this problem, we derive a more
tractable problem before developing a very simple iterative algorithm based on
inner approximation method with polynomial computational complexity. Numerical
results show that our proposed methods with realistic parameters significantly
outperform the existing approaches in terms of the quality of channel estimate
and SE.Comment: This paper has been accepted for publication in proceedings of the
IEEE. arXiv admin note: substantial text overlap with arXiv:1910.0129
On the Spectral and Energy Efficiencies of Full-Duplex Cell-Free Massive MIMO
In-band full-duplex (FD) operation is practically more suited for short-range
communications such as WiFi and small-cell networks, due to its current
practical limitations on the self-interference cancellation. In addition,
cell-free massive multiple-input multiple-output (CF-mMIMO) is a new and
scalable version of MIMO networks, which is designed to bring service antennas
closer to end user equipments (UEs). To achieve higher spectral and energy
efficiencies (SE-EE) of a wireless network, it is of practical interest to
incorporate FD capability into CF-mMIMO systems to utilize their combined
benefits. We formulate a novel and comprehensive optimization problem for the
maximization of SE and EE in which power control, access point-UE (AP-UE)
association and AP selection are jointly optimized under a realistic power
consumption model, resulting in a difficult class of mixed-integer nonconvex
programming. To tackle the binary nature of the formulated problem, we propose
an efficient approach by exploiting a strong coupling between binary and
continuous variables, leading to a more tractable problem. In this regard, two
low-complexity transmission designs based on zero-forcing (ZF) are proposed.
Combining tools from inner approximation framework and Dinkelbach method, we
develop simple iterative algorithms with polynomial computational complexity in
each iteration and strong theoretical performance guaranteed. Furthermore,
towards a robust design for FD CF-mMIMO, a novel heap-based pilot assignment
algorithm is proposed to mitigate effects of pilot contamination. Numerical
results show that our proposed designs with realistic parameters significantly
outperform the well-known approaches (i.e., small-cell and collocated mMIMO) in
terms of the SE and EE. Notably, the proposed ZF designs require much less
execution time than the simple maximum ratio transmission/combining.Comment: This paper was submitted for possible publicatio