TY - GEN
T1 - Energy efficient beam-alignment in millimeter wave networks
AU - Hussain, Muddassar
AU - Michelusi, Nicolo
N1 - Funding Information:
This research has been funded by NSF under grant CNS-1642982.
Funding Information:
M. Hussain and N. Michelusi are with the School of Electrical and Computer Engineering, Purdue University. email: {hussai13,michelus}@purdue.edu. This research has been funded by NSF under grant CNS-1642982.
Publisher Copyright:
© 2017 IEEE.
PY - 2018/4/10
Y1 - 2018/4/10
N2 - Millimeter wave communications rely on narrow-beam transmissions to cope with the strong signal attenuation at these frequencies, thus demanding precise beam-alignment between transmitter and receiver. The resulting signaling overhead may become excessive, especially in mobile environments. This paper addresses the energy efficient design of the beam-alignment protocol, with the goal of minimizing power consumption under a transmission rate constraint. The optimality of fractional search is proved, which allocates a given fraction of the interval of uncertainty on the mobile user's angular coordinate during beam-alignment. The fractional value is shown to be a function of the communication-sensing energy ratio: when large, a wider beam is selected and the fractional value approaches 1/2 (bisection); when small, a narrower beam is used to reduce the energy cost of sensing; finally, when smaller than 1/2, sensing is suboptimal. It is proved that the energy consumption under fractional search is smaller than that under bisection by at least a quantity proportional to the product of the minimum energy per radian used during beam-alignment, and the initial uncertainty on the mobile user's angular coordinate. Numerical results demonstrate a 2dB reduction in the average power consumption compared to bisection, for a wide range of rates.
AB - Millimeter wave communications rely on narrow-beam transmissions to cope with the strong signal attenuation at these frequencies, thus demanding precise beam-alignment between transmitter and receiver. The resulting signaling overhead may become excessive, especially in mobile environments. This paper addresses the energy efficient design of the beam-alignment protocol, with the goal of minimizing power consumption under a transmission rate constraint. The optimality of fractional search is proved, which allocates a given fraction of the interval of uncertainty on the mobile user's angular coordinate during beam-alignment. The fractional value is shown to be a function of the communication-sensing energy ratio: when large, a wider beam is selected and the fractional value approaches 1/2 (bisection); when small, a narrower beam is used to reduce the energy cost of sensing; finally, when smaller than 1/2, sensing is suboptimal. It is proved that the energy consumption under fractional search is smaller than that under bisection by at least a quantity proportional to the product of the minimum energy per radian used during beam-alignment, and the initial uncertainty on the mobile user's angular coordinate. Numerical results demonstrate a 2dB reduction in the average power consumption compared to bisection, for a wide range of rates.
KW - Markov decision process
KW - Millimeter Wave
KW - beam-alignment
KW - initial access
UR - http://www.scopus.com/inward/record.url?scp=85051036619&partnerID=8YFLogxK
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U2 - 10.1109/ACSSC.2017.8335545
DO - 10.1109/ACSSC.2017.8335545
M3 - Conference contribution
AN - SCOPUS:85051036619
T3 - Conference Record of 51st Asilomar Conference on Signals, Systems and Computers, ACSSC 2017
SP - 1219
EP - 1223
BT - Conference Record of 51st Asilomar Conference on Signals, Systems and Computers, ACSSC 2017
A2 - Matthews, Michael B.
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 51st Asilomar Conference on Signals, Systems and Computers, ACSSC 2017
Y2 - 29 October 2017 through 1 November 2017
ER -