16,280 research outputs found
Ubiquitous Cell-Free Massive MIMO Communications
Since the first cellular networks were trialled in the 1970s, we have
witnessed an incredible wireless revolution. From 1G to 4G, the massive traffic
growth has been managed by a combination of wider bandwidths, refined radio
interfaces, and network densification, namely increasing the number of antennas
per site. Due its cost-efficiency, the latter has contributed the most. Massive
MIMO (multiple-input multiple-output) is a key 5G technology that uses massive
antenna arrays to provide a very high beamforming gain and spatially
multiplexing of users, and hence, increases the spectral and energy efficiency.
It constitutes a centralized solution to densify a network, and its performance
is limited by the inter-cell interference inherent in its cell-centric design.
Conversely, ubiquitous cell-free Massive MIMO refers to a distributed Massive
MIMO system implementing coherent user-centric transmission to overcome the
inter-cell interference limitation in cellular networks and provide additional
macro-diversity. These features, combined with the system scalability inherent
in the Massive MIMO design, distinguishes ubiquitous cell-free Massive MIMO
from prior coordinated distributed wireless systems. In this article, we
investigate the enormous potential of this promising technology while
addressing practical deployment issues to deal with the increased
back/front-hauling overhead deriving from the signal co-processing.Comment: Published in EURASIP Journal on Wireless Communications and
Networking on August 5, 201
Resource allocation in OFDMA networks with half-duplex and imperfect full-duplex users
Recent studies indicate the feasibility of in-band fullduplex (FD) wireless
communications, where a wireless radio transmits and receives simultaneously in
the same band. Due to its potential to increase the capacity, analyzing the
performance of a cellular network that contains full-duplex devices is crucial.
In this paper, we consider maximizing the weighted sum-rate of downlink and
uplink of a single cell OFDMA network which consists of an imperfect FD
base-station (BS) and a mixture of half-duplex and imperfect full-duplex mobile
users. To this end, the joint problem of sub-channel assignment and power
allocation is investigated and a two-step solution is proposed. A heuristic
algorithm to allocate each sub-channel to a pair of downlink and uplink users
with polynomial complexity is presented. The power allocation problem is
convexified based on the difference of two concave functions approach, for
which an iterative solution is obtained. Simulation results demonstrate that
when all the users and the BS are perfect FD nodes the network throughput could
be doubled, Otherwise, the performance improvement is limited by the inter-node
interference and the self-interference. We also investigate the effect of the
self-interference cancellation capability and the percentage of FD users on the
network performance in both indoor and outdoor scenarios.Comment: 6 pages, 8 figures, Accepted in IEEE International Conference on
Communication (ICC), Malaysia, 201
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