40 research outputs found
A Dynamic Clustering and Resource Allocation Algorithm for Downlink CoMP Systems with Multiple Antenna UEs
Coordinated multi-point (CoMP) schemes have been widely studied in the recent
years to tackle the inter-cell interference. In practice, latency and
throughput constraints on the backhaul allow the organization of only small
clusters of base stations (BSs) where joint processing (JP) can be implemented.
In this work we focus on downlink CoMP-JP with multiple antenna user equipments
(UEs) and propose a novel dynamic clustering algorithm. The additional degrees
of freedom at the UE can be used to suppress the residual interference by using
an interference rejection combiner (IRC) and allow a multistream transmission.
In our proposal we first define a set of candidate clusters depending on
long-term channel conditions. Then, in each time block, we develop a resource
allocation scheme by jointly optimizing transmitter and receiver where: a)
within each candidate cluster a weighted sum rate is estimated and then b) a
set of clusters is scheduled in order to maximize the system weighted sum rate.
Numerical results show that much higher rates are achieved when UEs are
equipped with multiple antennas. Moreover, as this performance improvement is
mainly due to the IRC, the gain achieved by the proposed approach with respect
to the non-cooperative scheme decreases by increasing the number of UE
antennas.Comment: 27 pages, 8 figure
Enabling Ultra Reliable Wireless Communications for Factory Automation with Distributed MIMO
Factory automation is one of the most challenging use cases for 5G-and-beyond
mobile networks due to strict latency, availability and reliability
constraints. In this work, an indoor factory scenario is considered, and
distributed multiple-input multiple-output (MIMO) schemes are investigated in
order to enable reliable communication to the actuators (ACs) active in the
factory. Different levels of coordination among the access points serving the
ACs and several beamforming schemes are considered and analyzed. To enforce
system reliability, a max-min power allocation (MPA) algorithm is proposed,
aimed at improving the signal to interference plus noise ratio (SINR) of the
ACs with the worst channel conditions. Extensive system simulations are
performed in a realistic scenario, which includes a new path-loss model based
on recent measurements in factory scenarios, and, also, the presence of
non-Gaussian impulsive noise. Numerical results show that distributed MIMO
schemes with zero-forcing (ZF) beamforming and MPA have the potential of
providing SINR gains in the order of tens of dB with respect to a centralized
MIMO deployment, as well as that the impulsive noise can strongly degrade the
system performance and thus requires specific detection and mitigation
techniques.Comment: Accepted at the IEEE Vehicular Technology Conference (VTC-Fall),
Honolulu (HI), Sep. 201
Indoor Massive MIMO Deployments for Uniformly High Wireless Capacity
Providing consistently high wireless capacity is becoming increasingly
important to support the applications required by future digital enterprises.
In this paper, we propose Eigen-direction-aware ZF (EDA-ZF) with partial
coordination among base stations (BSs) and distributed interference suppression
as a practical approach to achieve this objective. We compare our solution with
Zero Forcing (ZF), entailing neither BS coordination or inter-cell interference
mitigation, and Network MIMO (NeMIMO), where full BS coordination enables
centralized inter-cell interference management. We also evaluate the
performance of said schemes for three sub-6 GHz deployments with varying BS
densities -- sparse, intermediate, and dense -- all with fixed total number of
antennas and radiated power. Extensive simulations show that: (i) indoor
massive MIMO implementing the proposed EDA-ZF provides uniformly good rates for
all users; (ii) indoor network densification is detrimental unless full
coordination is implemented; (iii) deploying NeMIMO pays off under strong
outdoor interference, especially for cell-edge users
Distributed MIMO for 6G sub-Networks in the Unlicensed Spectrum
In this paper, we consider the sixth generation (6G) sub-networks, where
hyper reliable low latency communications (HRLLC) requirements are expected to
be met. We focus on a scenario where multiple sub-networks are active in the
service area and assess the feasibility of using the 6 GHz unlicensed spectrum
to operate such deployment, evaluating the impact of listen before talk (LBT).
Then, we explore the benefits of using distributed multiple input multiple
output (MIMO), where the available antennas in every sub-network are
distributed over a number of access points (APs). Specifically, we compare
different configurations of distributed MIMO with respect to centralized MIMO,
where a single AP with all antennas is located at the center of every
sub-network.Comment: This paper is accepted for publication in 2023 IEEE Conference on
Standards for Communications and Networking (CSCN
Uplink Sounding Reference Signal Coordination to Combat Pilot Contamination in 5G Massive MIMO
To guarantee the success of massive multiple-input multiple-output (MIMO),
one of the main challenges to solve is the efficient management of pilot
contamination. Allocation of fully orthogonal pilot sequences across the
network would provide a solution to the problem, but the associated overhead
would make this approach infeasible in practical systems. Ongoing
fifth-generation (5G) standardisation activities are debating the amount of
resources to be dedicated to the transmission of pilot sequences, focussing on
uplink sounding reference signals (UL SRSs) design. In this paper, we
extensively evaluate the performance of various UL SRS allocation strategies in
practical deployments, shedding light on their strengths and weaknesses.
Furthermore, we introduce a novel UL SRS fractional reuse (FR) scheme, denoted
neighbour-aware FR (FR-NA). The proposed FR-NA generalizes the fixed reuse
paradigm, and entails a tradeoff between i) aggressively sharing some UL SRS
resources, and ii) protecting other UL SRS resources with the aim of relieving
neighbouring BSs from pilot contamination. Said features result in a cell
throughput improvement over both fixed reuse and state-of-the-art FR based on a
cell-centric perspective