AY4434 Occupancy Analysis of the 24GHz ISM Band.ppt

AY4434Occupancy Analysis of the 2.4GHz ISM Band Mike Biggs, mbiggs@mass.co.uk Simon Day , swd@ Presentation Contents Introduction to MASS 2.4GHz Monitoring Exercise Scenario Objectives Equipment Measurement and Analysis Techniques Surveys Results Conclusions Questions Mass Consultants – Who Are We? Systems House 3 Divisions Systems Engineering Real-Time Systems Managed Services Vital Statistics 100 people strong Turnover ~ ￡12M 90% defence Based in St Neots Eurofighter in the Electronic Warfare Test Facility MASS and RA RA concerned with the effects of radio interference Jamming is intentional RF interference Applied EW expertise to commercial radiocomms 3 projects for RA AY4119 - Man-Made Noise Measurement Programme AY4364 - EMC Implications of Software Radio AY4434 - 2.4GHz Monitoring Exercise 2.4GHz Monitoring Exercise- Scenario 2,400MHz to 2,483.5MHz ISM band Many uncoordinated services Microwave oven leakage Broadcasting services RF identification devices Licensed FWA systems BlueTooth WLAN / WiFi / IEEE802.11b Danger of band congestion Objectives Assess band occupancy Time-varying nature of usage Spatial distribution of users Investigate anecdotal evidence of WLAN congestion Many instances reported to RA Is there any evidence of congestion? If so, why is it occurring? Equipment Omni antenna Spectrum analyser Laptop PC Bespoke data logging software Measurement Process Continuously scan band of interest Include 30MHz ‘guard bands’ to check for out-of-band activity Use 1 MHz bandwidth Data collected in 10-minute blocks 10,000 samples Good statistical set Tangible period of time Activity Percentile Plot Reference Study 1 Reference Study 2 Surveys Private Sector Duration Internet café 1? hrs Hub of broadband wireless provider 24 hrs Roving exercise around Cambridge 1 day Public Sector Primary school school hrs Secondary school school hrs Cambridge hospital 24 hrs Heathrow airport 2 hrs City centre London 7 days Glasgow 7 days Cambr