221 research outputs found
Temporal Analysis of Measured LOS Massive MIMO Channels with Mobility
The first measured results for massive multiple-input, multiple-output (MIMO)
performance in a line-of-sight (LOS) scenario with moderate mobility are
presented, with 8 users served by a 100 antenna base Station (BS) at 3.7 GHz.
When such a large number of channels dynamically change, the inherent
propagation and processing delay has a critical relationship with the rate of
change, as the use of outdated channel information can result in severe
detection and precoding inaccuracies. For the downlink (DL) in particular, a
time division duplex (TDD) configuration synonymous with massive MIMO
deployments could mean only the uplink (UL) is usable in extreme cases.
Therefore, it is of great interest to investigate the impact of mobility on
massive MIMO performance and consider ways to combat the potential limitations.
In a mobile scenario with moving cars and pedestrians, the correlation of the
MIMO channel vector over time is inspected for vehicles moving up to 29 km/h.
For a 100 antenna system, it is found that the channel state information (CSI)
update rate requirement may increase by 7 times when compared to an 8 antenna
system, whilst the power control update rate could be decreased by at least 5
times relative to a single antenna system.Comment: Accepted for presentation at the 85th IEEE Vehicular Technology
Conference in Sydney. 5 Pages. arXiv admin note: substantial text overlap
with arXiv:1701.0881
Serving 22 Users in Real-Time with a 128-Antenna Massive MIMO Testbed
This paper presents preliminary results for a novel 128-antenna massive Multiple-Input, Multiple-Output (MIMO) testbed developed through Bristol Is Open in collaboration with National Instruments and Lund University. We believe that the results presented here validate the adoption of massive MIMO as a key enabling technology for 5G and pave the way for further pragmatic research by the massive MIMO community. The testbed operates in real-time with a Long-Term Evolution (LTE)-like PHY in Time Division Duplex (TDD) mode and supports up to 24 spatial streams, providing an excellent basis for comparison with existing standards and complimentary testbeds. Through line-of-sight (LOS) measurements at 3.51 GHz in an indoor atrium environment with 12 user clients, an uncoded system sum-rate of 1.59 Gbps was achieved in real-time using a single 20 MHz LTE band, equating to 79.4 bits/s/Hz. In a subsequent indoor trial, 22 user clients were successfully served, which would equate to 145.6 bits/s/Hz using the same frame schedule. To the best of the author's knowledge, these are the highest spectral efficiencies achieved for any wireless system to date
Performance characterization of a real-time massive MIMO system with LOS mobile channels
The first measured results for massive MIMO performance in a line-of-sight
(LOS) scenario with moderate mobility are presented, with 8 users served in
real-time using a 100-antenna base Station (BS) at 3.7 GHz. When such a large
number of channels dynamically change, the inherent propagation and processing
delay has a critical relationship with the rate of change, as the use of
outdated channel information can result in severe detection and precoding
inaccuracies. For the downlink (DL) in particular, a time division duplex (TDD)
configuration synonymous with massive multiple-input, multiple-output (MIMO)
deployments could mean only the uplink (UL) is usable in extreme cases.
Therefore, it is of great interest to investigate the impact of mobility on
massive MIMO performance and consider ways to combat the potential limitations.
In a mobile scenario with moving cars and pedestrians, the massive MIMO channel
is sampled across many points in space to build a picture of the overall user
orthogonality, and the impact of both azimuth and elevation array
configurations are considered. Temporal analysis is also conducted for vehicles
moving up to 29km/h and real-time bit error rates (BERs) for both the UL and DL
without power control are presented. For a 100-antenna system, it is found that
the channel state information (CSI) update rate requirement may increase by 7
times when compared to an 8-antenna system, whilst the power control update
rate could be decreased by at least 5 times relative to a single antenna
system.Comment: Submitted to the 2017 IEEE JSAC Special Issue on Deployment Issues
and Performance Challenges for 5G, IEEE Journal on Selected Areas in
Communications, 2017, vol.PP, no.99, pp.1-
Separation Framework: An Enabler for Cooperative and D2D Communication for Future 5G Networks
Soaring capacity and coverage demands dictate that future cellular networks
need to soon migrate towards ultra-dense networks. However, network
densification comes with a host of challenges that include compromised energy
efficiency, complex interference management, cumbersome mobility management,
burdensome signaling overheads and higher backhaul costs. Interestingly, most
of the problems, that beleaguer network densification, stem from legacy
networks' one common feature i.e., tight coupling between the control and data
planes regardless of their degree of heterogeneity and cell density.
Consequently, in wake of 5G, control and data planes separation architecture
(SARC) has recently been conceived as a promising paradigm that has potential
to address most of aforementioned challenges. In this article, we review
various proposals that have been presented in literature so far to enable SARC.
More specifically, we analyze how and to what degree various SARC proposals
address the four main challenges in network densification namely: energy
efficiency, system level capacity maximization, interference management and
mobility management. We then focus on two salient features of future cellular
networks that have not yet been adapted in legacy networks at wide scale and
thus remain a hallmark of 5G, i.e., coordinated multipoint (CoMP), and
device-to-device (D2D) communications. After providing necessary background on
CoMP and D2D, we analyze how SARC can particularly act as a major enabler for
CoMP and D2D in context of 5G. This article thus serves as both a tutorial as
well as an up to date survey on SARC, CoMP and D2D. Most importantly, the
article provides an extensive outlook of challenges and opportunities that lie
at the crossroads of these three mutually entangled emerging technologies.Comment: 28 pages, 11 figures, IEEE Communications Surveys & Tutorials 201
Predictor Antenna: A Technique to Boost the Performance of Moving Relays
In future wireless systems, a large number of users may access the networks via moving relays (MRs) installed on top of vehicles. One of the main challenges of MRs is rapid channel variation which may make channel estimation, and its following procedures, difficult. To address these issues, various schemes are designed, among which predictor antenna (PA) is a candidate. The PA setup refers to a system with two (sets of) antennas on top of a vehicle, where the PA(s) positioned in front of the vehicle is(are) utilized to predict the channel state information required for data transmission to the receive antennas (RAs) aligned behind the PA. In this paper, we introduce the concept and the potentials of PA systems. Moreover, summarizing the field trials for PAs and the 3GPP attempts on (moving) relays, we compare the performance of different PA and non-PA methods for vehicle communications in both urban and rural areas with the PA setup backhauled through terrestrial or satellite technology, respectively. As we show, with typical parameter settings and vehicle speeds, a single-antenna PA-assisted setup can boost the backhaul throughput of MRs, compared to state-of-the-art open-loop schemes, by up to 50%
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