10 research outputs found
Massive MIMO for Ultra-reliable Communications with Constellations for Dual Coherent-noncoherent Detection
The stringent requirements of ultra-reliable low-latency communications
(URLLC) require rethinking of the physical layer transmission techniques.
Massive antenna arrays are seen as an enabler of the emerging
generation systems, due to increases in spectral efficiency and degrees of
freedom for transmissions, which can greatly improve reliability under
demanding latency requirements. Massive array coherent processing relies on
accurate channel state information (CSI) in order to achieve high reliability.
In this paper, we investigate the impact of imperfect CSI in a single-input
multiple-output (SIMO) system on the coherent receiver. An amplitude-phase
keying (APK) symbol constellation is proposed, where each two symmetric symbols
reside on distinct power levels. The symbols are demodulated using a dual-stage
non-coherent and coherent detection strategy, in order to improve symbol
reliability. By means of analysis and simulation, we find an adequate scaling
of the constellation and show that for high signal-to-noise ratio (SNR) and
inaccurate CSI regime, the proposed scheme enhances receiver performance.Comment: Accepted at WSA 2018, special session on "Massive MIMO for mobile
broadband communications and new 5G services
Massive MIMO for Internet of Things (IoT) Connectivity
Massive MIMO is considered to be one of the key technologies in the emerging
5G systems, but also a concept applicable to other wireless systems. Exploiting
the large number of degrees of freedom (DoFs) of massive MIMO essential for
achieving high spectral efficiency, high data rates and extreme spatial
multiplexing of densely distributed users. On the one hand, the benefits of
applying massive MIMO for broadband communication are well known and there has
been a large body of research on designing communication schemes to support
high rates. On the other hand, using massive MIMO for Internet-of-Things (IoT)
is still a developing topic, as IoT connectivity has requirements and
constraints that are significantly different from the broadband connections. In
this paper we investigate the applicability of massive MIMO to IoT
connectivity. Specifically, we treat the two generic types of IoT connections
envisioned in 5G: massive machine-type communication (mMTC) and ultra-reliable
low-latency communication (URLLC). This paper fills this important gap by
identifying the opportunities and challenges in exploiting massive MIMO for IoT
connectivity. We provide insights into the trade-offs that emerge when massive
MIMO is applied to mMTC or URLLC and present a number of suitable communication
schemes. The discussion continues to the questions of network slicing of the
wireless resources and the use of massive MIMO to simultaneously support IoT
connections with very heterogeneous requirements. The main conclusion is that
massive MIMO can bring benefits to the scenarios with IoT connectivity, but it
requires tight integration of the physical-layer techniques with the protocol
design.Comment: Submitted for publicatio
A Novel Receiver Design with Joint Coherent and Non-Coherent Processing
In this paper, we propose a novel splitting receiver,
which involves joint processing of coherently and non-coherently
received signals. Using a passive RF power splitter, the received
signal at each receiver antenna is split into two streams which
are then processed by a conventional coherent detection (CD)
circuit and a power-detection (PD) circuit, respectively. The
streams of the signals from all the receiver antennas are then
jointly used for information detection. We show that the splitting
receiver creates a three-dimensional received signal space, due
to the joint coherent and non-coherent processing. We analyze
the achievable rate of a splitting receiver, which shows that the
splitting receiver provides a rate gain of 3/2 compared to either
the conventional (CD-based) coherent receiver or the PD-based
non-coherent receiver in the high SNR regime. We also analyze
the symbol error rate (SER) for practical modulation schemes,
which shows that the splitting receiver achieves asymptotic SER
reduction by a factor of at least √
M −1 for M-QAM compared
to either the conventional (CD-based) coherent receiver or the
PD-based non-coherent receiver.ARC Discovery Projects Grant DP14010113