Sensor assisted movement identification and prediction for beamformed 60 GHz links

Abstract

The 60 GHz frequency band promises very high data rates -in the order of Gb/s -due to the availability of large amounts of bandwidth. High freespace path loss at the 60 GHz frequency band makes it necessary to employ beamforming capable directional antennas to confine signal power in the desired direction. When beamforming is used, the links are sensitive to misalignment in antenna directionality, due to the movement of devices. To identify and circumvent the misalignments, we propose to use motion sensors (i.e., accelerometer and gyroscope) which are already present in most modern mobile devices. By finding the extent of misaligned beams, corrective actions are carried out to reconfigure the antennas. Motion sensors in mobile devices provide means to estimate the extent of misalignments. We collected real data from motion sensors and steered the beams appropriately. The results from our study show that the sensors are capable of detecting the cause of the error as translational or rotational movements. Furthermore it is also shown that sensor data can be used to predict the next location of the user. This can be used to reconfigure the directional antenna to switch the antenna beam and hence avoid frequent link disruptions. This decreases the number of beam searches, thus lowering the MAC overhead.iv Preface During my Embedded Systems master I always tried to achieve a broad understanding in many topics related to embedded systems. My graduation project has been no different, it was yet another unexplored topic; wireless communications. This past year I worked not only on wireless communications, but also learnt the ups and downs of being on the forefront of academic research. The result of which is not only this M.Sc. thesis, but also two published papers at the IEEE Consumer Communications and Networking Conference (CCNC).

Millimeter Wave Communications for Future Mobile Networks

“…Moreover, limited feedback may also cause the transmitter having only partial channel information and thus beaming misalignment [45]. 2) Mobility of communication UE [46], [47], which invokes tracking error and system reaction delay. Hardware impairments and design challenges: In addition to above challenges, practical transceiver hardware are impaired by phase noise (PN), non-linear PAs, I/Q imbalance, and limited ADC resolution [48].…”

Millimeter-Wave Communication for Internet of Vehicles: Status, Challenges, and Perspectives

“…In a vehicular environment, beam alignment is even more challenging because it should be complete in a very short period of time. Very fast beam alignment techniques need to be developed to meet the vehicle's mobility requirements [146], [147]. Thereafter, beam tracking is required to maintain the alignment of beams between the transmitter and the receiver.…”

Location-Assisted Beam Alignment for Train-to-Train Communication in Urban Rail Transit System

“…When T A and T B are connected, we assume that their beams are aligned. However, translational and rotational motions can result in frequent link degradation [31]. If T A and T B start moving in a linear direction, both trains need to be properly steered in the right direction, and usually the best beams point directly to each other, which can be called ''LOS beams''.…”

“…In [30], in order to minimize the temporal overhead required to achieve beam alignment, a method of designing beamforming and combining vectors using position information exchanged between nodes has been proposed. By using sensors on the device, a priori knowledge of the potential pointing direction for reliable beam alignment can be provided to configure the antennas [31]- [33].…”