An empirical assessment of Quasi-permanently vacant channels in mobile communication bands for cognitive radio

Abstract

Basis of cognitive radio is to exploit unused frequency channels in licensed band. Recently standardised IEEE 802.22 set of cognitive radio protocols envisages fixed and nomadic receivers at below 800 MHz bands. Radio link design for this cognitive radio consider that the channels are available only dynamically to secondary users. Scanning period is thus embedded in link layer control as overhead and reduces overall efficiency of cognitive radio technology. For mobile receivers, availability of permanent channels for radio link control is essential for in-band signalling. Existing mobile communication system uses CDMA 800, GSM 900, GSM 1800 and WCDMA 2000 MHz bands for which approximately 1/8 th of the band capacity is used for in-band signalling. Present work provides an assessment of vacant channels in mobile communications range which were permanently available at the time of measurement. The study used conventional Radio frequency scanners available for different bands and dedicated engineering handsets for tracking active frequencies. The tests were performed with assemblies carried in a vehicle and across the length and breadth of each city. The allotment of frequencies by Frequency Regulatory Authority to local mobile operators along with the frequency bands reserved for further distribution were also considered. The experimentally collected data were analysed using RF analysis software and spread sheet database. An analysis of the collected data lead to arrive at the conclusion that more than 1/8 th part of resources of each band are nearly permanently vacant which is enough to design inband common control signalling methods for cognitive radio. Also, from collected data of eight cities, an empirical relationship has been established which can be taken as a thumb rule for projection of channel occupancy from densely populated core areas of big cities to scanty populated township areas when population is known.

A Quality of Service Based Model for Supporting Mobile Secondary Users in Cognitive Radio Technology

“…for ζ ¼ 0 and h p ¼ ζ:w t þ 1 ðÞ 1=ζ ; for ζ 6 ¼ 0 (26) where, h p = optimal holding (service) time of the user at time t.…”

Call Arrival Rate Prediction and Blocking Probability Estimation for Infrastructure based Mobile Cognitive Radio Personal Area Network

“…The present document shall use the SU and Cognitive Radio-User Equipment (CR-UE) interchangeably. In previous study [12,13], it has been established that more than 20% of the completely licensed bandwidth is practically vacant in a saturated market environment. This is well above the requirement of 1/8th part of the band to get access to the whole of the bandwidth at a time and adequate to take additional Media Access Control(MAC) level overhead required for C. There is no immediate necessity of these channels by the licensed operators which can be safely deployed as common control channel for cognitive radio purpose.…”

Assessment of spectral efficiency about 900 MHz using GSM and CDMA technologies for mobile cognitive radio

“…Availability of quasi-permanently vacant channels to the minimum extent of 1/8 th part of the total band in GSM and CDMA has been established in [4] which can be used as fixed channels of cognitive radio technology for control channel purposes. Cognitive Radio uses Cognitive Pilot Channel (CPC) to push information to cognitive radio nodes about operators, policies, access technologies etc and Cognitive Control Channels (CCC) to broadcast local availability of different bands, spectrum sensing information, spectrum needs of different systems, rules for accessing specific bands etc [6].…”