5 research outputs found
On the Relay-Fallback Tradeoff in Millimeter Wave Wireless System
Millimeter wave (mmWave) communications systems are promising candidate to
support extremely high data rate services in future wireless networks. MmWave
communications exhibit high penetration loss (blockage) and require directional
transmissions to compensate for severe channel attenuations and for high noise
powers. When blockage occurs, there are at least two simple prominent options:
1) switching to the conventional microwave frequencies (fallback option) and 2)
using an alternative non-blocked path (relay option). However, currently it is
not clear under which conditions and network parameters one option is better
than the other. To investigate the performance of the two options, this paper
proposes a novel blockage model that allows deriving maximum achievable
throughput and delay performance of both options. A simple criterion to decide
which option should be taken under which network condition is provided. By a
comprehensive performance analysis, it is shown that the right option depends
on the payload size, beam training overhead, and blockage probability. For a
network with light traffic and low probability of blockage in the direct link,
the fallback option is throughput- and delay-optimal. For a network with heavy
traffic demands and semi-static topology (low beam-training overhead), the
relay option is preferable.Comment: 6 pages, 5 figures, accepted in IEEE INFOCOM mmNet Worksho
On the Benefits of Network-Level Cooperation in Millimeter-Wave Communications
Relaying techniques for millimeter-wave wireless networks represent a
powerful solution for improving the transmission performance. In this work, we
quantify the benefits in terms of delay and throughput for a random-access
multi-user millimeter-wave wireless network, assisted by a full-duplex network
cooperative relay. The relay is equipped with a queue for which we analyze the
performance characteristics (e.g., arrival rate, service rate, average size,
and stability condition). Moreover, we study two possible transmission schemes:
fully directional and broadcast. In the former, the source nodes transmit a
packet either to the relay or to the destination by using narrow beams,
whereas, in the latter, the nodes transmit to both the destination and the
relay in the same timeslot by using a wider beam, but with lower beamforming
gain. In our analysis, we also take into account the beam alignment phase that
occurs every time a transmitter node changes the destination node. We show how
the beam alignment duration, as well as position and number of transmitting
nodes, significantly affect the network performance. Moreover, we illustrate
the optimal transmission scheme (i.e., broadcast or fully directional) for
several system parameters and show that a fully directional transmission is not
always beneficial, but, in some scenarios, broadcasting and relaying can
improve the performance in terms of throughput and delay.Comment: arXiv admin note: text overlap with arXiv:1804.0945