12 research outputs found
Coverage Analysis of Relay Assisted Millimeter Wave Cellular Networks with Spatial Correlation
We propose a novel analytical framework for evaluating the coverage
performance of a millimeter wave (mmWave) cellular network where idle user
equipments (UEs) act as relays. In this network, the base station (BS) adopts
either the direct mode to transmit to the destination UE, or the relay mode if
the direct mode fails, where the BS transmits to the relay UE and then the
relay UE transmits to the destination UE. To address the drastic rotational
movements of destination UEs in practice, we propose to adopt selection
combining at destination UEs. New expression is derived for the
signal-to-interference-plus-noise ratio (SINR) coverage probability of the
network. Using numerical results, we first demonstrate the accuracy of our new
expression. Then we show that ignoring spatial correlation, which has been
commonly adopted in the literature, leads to severe overestimation of the SINR
coverage probability. Furthermore, we show that introducing relays into a
mmWave cellular network vastly improves the coverage performance. In addition,
we show that the optimal BS density maximizing the SINR coverage probability
can be determined by using our analysis
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