KPI Science News (May 2019)

AN UPLINK POWER CONTROL ROUTINE FOR QUALITY-OF-SERVICE EQUALIZATION IN WIRELESS DATA TRANSFER NETWORKS CONSTRAINED TO EQUIDISTANT POWER LEVELS

  • Vadim V. Romanuke

DOI
https://doi.org/10.20535/kpi-sn.2019.2.160199
Journal volume & issue
no. 2

Abstract

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Background. Power control is a process of adjusting transmitter power output in a communication system to achieve satisfactory performance within the system. In wireless data transfer networks, this process refers to uplink connection, when information about the transmitter power output is sent to the base station, whereupon the power is adjusted in accordance with one or more transmit power control commands received in the downlink. The uplink power control is intended to ensure quality of service declared by the system provider including maintaining a sufficient signal-to-noise ratio and link data rate, reducing interference, overloading, and preserving the battery life. Objective. Whereas the sum of power levels is constrained to the grand total of the powers transmitted in the uplink off all the transmitters, the quality-of-service equalization is a fundamental task. Henceforward, for a set of equidistant power levels, the goal is to achieve the quality-of-service equalization by non-decreasing powers when moving away from the base station with using the distances from the mobiles to the base station. Inasmuch as the uplink power grand total is “allowed”, the sum of all the powers should be as much as closer to the grand total. Methods. Principally, ratios of distances to the base station are calculated using an initial value of the path loss exponent. Then the case of the overloaded network is checked out. After that, the base station power responses are calculated using the ratios and the principle of the equal quality of service, wherein the received uplink power should be closely the same for all the users by every uplink transmission. If the farthest/closest transmitters’ powers are out of the power range, they are set down/up to the proper maximum/minimum. The path loss exponent is decreased if the proper maximum is re-violated. Finally, the base station power responses are rounded to values within a set of power levels. Results. The suggested algorithm deals with powers in watts fitting wireless data transfer networks working in shallow areas (like Wi-Fi, Bluetooth, etc.), for which the number of power levels is relatively great and the range of active uplink transmission powers is relatively narrow. The routine which implements the algorithm still can be optimized depending on the programming environment and paradigm. For instance, C++ and Python will fit for speeding up the performance. Nevertheless, the routine would not sustain the UMTS update frequency, unless a network works with a few tens of users. Conclusions. The uplink power control routine stated with the six algorithmic items effectively equalizes quality of service in shallow wireless data transfer networks, where user uplink powers are constrained to equidistant power levels in watts. It is not a one-step but a multi-step process during which four types of conditions are successively tried to get satisfied. Eventually, the factual sum of all the powers transmitted in the uplink may become “harmlessly” less than the grand total.

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