4 research outputs found
Full-Duplex Cellular Networks: It Works!
Full-duplex (FD) communications with bidirectional transmitting and receiving
at the same time and frequency radio resource have long been deemed a promising
way to boost spectrum efficiency, but hindered by the techniques for
self-interference cancellation (SIC). Recent breakthroughs in analog and
digital signal processing yield the feasibility of beyond dB SIC
capability and make it possible for FD communications to demonstrate nearly
doubled spectrum efficiency for point-to-point links. Now it is time to shift
at least partial of our focus to full duplex networking, such as in cellular
networks, since it is not straightforward but demanding novel and more
complicated interference management techniques. Before putting FD networking
into practice, we need to understand that what scenarios FD communications
should be applied in under the current technology maturity, how bad the
performance will be if we do nothing to deal with the newly introduced
interference, and most importantly, how much improvement could be achieved
after applying advanced solutions. This article will shed light on these
questions
Leveraging One-hop Information in Massive MIMO Full-Duplex Wireless Systems
We consider a single-cell massive MIMO full-duplex wireless communication
system, where the base-station (BS) is equipped with a large number of
antennas. We consider the setup where the single-antenna mobile users operate
in half- duplex, while each antenna at the BS is capable of full-duplex
transmissions, i.e., it can transmit and receive simultaneously using the same
frequency spectrum. The fundamental challenge in this system is intra-cell
inter-node interference, generated by the transmissions of uplink users to the
receptions at the downlink users. The key operational challenge is estimating
and aggregating inter-mobile channel estimates, which can potentially overwhelm
any gains from full-duplex operation.
In this work, we propose a scalable and distributed scheme to optimally
manage the inter-node interference by utilizing a "one- hop information
architecture". In this architecture, the BS only needs to know the
signal-to-interference-plus-noise ratio (SINR) from the downlink users. Each
uplink user needs its own SINR, along with a weighted signal-plus-noise metric
from its one-hop neighboring downlink users, which are the downlink users that
it interferes with. The proposed one-hop information architecture does not
require any network devices to comprehensively gather the vast inter-node
interference channel knowledge, and hence significantly reduces the overhead.
Based on the one-hop information architecture, we design a distributed power
control algorithm and implement such architecture using overheard feedback
information. We show that, in typical asymptotic regimes with many users and
antennas, the proposed distributed power control scheme improves the overall
network utility and reduces the transmission power of the uplink users.Comment: Submitted to IEEE/ACM Transactions on Networkin
User Selection and Power Allocation in Full Duplex Multi-Cell Networks
Full duplex (FD) communications has the potential to double the capacity of a
half duplex (HD) system at the link level. However, in a cellular network, FD
operation is not a straightforward extension of half duplex operations. The
increased interference due to a large number of simultaneous transmissions in
FD operation and realtime traffic conditions limits the capacity improvement.
Realizing the potential of FD requires careful coordination of resource
allocation among the cells as well as within the cell. In this paper, we
propose a distributed resource allocation, i.e., joint user selection and power
allocation for a FD multi-cell system, assuming FD base stations (BSs) and HD
user equipment (UEs). Due to the complexity of finding the globally optimum
solution, a sub-optimal solution for UE selection, and a novel geometric
programming based solution for power allocation, are proposed. The proposed
distributed approach converges quickly and performs almost as well as a
centralized solution, but with much lower signaling overhead. It provides a
hybrid scheduling policy which allows FD operations whenever it is
advantageous, but otherwise defaults to HD operation. We focus on small cell
systems because they are more suitable for FD operation, given practical
self-interference cancellation limits.With practical self-interference
cancellation, it is shown that the proposed hybrid FD system achieves nearly
two times throughput improvement for an indoor multi-cell scenario, and about
65% improvement for an outdoor multi-cell scenario compared to the HD system.Comment: 15 pages, to be published in IEEE Transactions on Vehicular
Technology, 2016. arXiv admin note: text overlap with arXiv:1412.870
Capacity Limits of Full-Duplex Cellular Network
This paper aims to characterize the capacity limits of a wireless cellular
network with a full-duplex (FD) base-station (BS) and half-duplex user
terminals, in which three independent messages are communicated: the uplink
message from the uplink user to the BS, the downlink message from
the BS to the downlink user, and the device-to-device (D2D) message from
the uplink user to the downlink user. From an information theoretical
perspective, the overall network can be viewed as a generalization of the FD
relay broadcast channel with a side message transmitted from the relay to the
destination. We begin with a simpler case that involves the uplink and downlink
transmissions of only, and propose an achievable rate region based
on a novel strategy that uses the BS as a FD relay to facilitate the
interference cancellation at the downlink user. We also prove a new converse,
which is strictly tighter than the cut-set bound, and characterize the capacity
region of the scalar Gaussian FD network without a D2D message to within a
constant gap. This paper further studies a general setup wherein
are communicated simultaneously. To account for the D2D
message, we incorporate Marton's broadcast coding into the previous scheme to
obtain a larger achievable rate region than the existing ones in the
literature. We also improve the cut-set bound by means of genie and show that
by using one of the two simple rate-splitting schemes, the capacity region of
the scalar Gaussian FD network with a D2D message can already be reached to
within a constant gap. Finally, a generalization to the vector Gaussian channel
case is discussed. Simulation results demonstrate the advantage of using the BS
as relay in enhancing the throughput of the FD cellular network.Comment: To appear in IEEE Transactions on Information Theor