1. Spread Spectrum Interference 1 WRAP 0975C

2. Spread Spectrum Interference in WRAP DS: Direct Sequence systems. Resulting S/I after de- spreading: S/I despread = S/I spread + Processing Gain FH: Frequency hopping systems. Interference is expressed as the percentage of time (“hops”) P int [%] = Probability that S/I < Required S/I Hybrid DS/FH systems. Interference is expressed as for FH, with calculations accounting for the DS processing gain. 2 WRAP 0975C

3. Parameters Direct Sequence: Processing gain [dB] given as a receiver parameter Frequency hopping: Type of frequency utilisation –Table-defined: Table of frequencies –Band-defined: Table of band limits, frequency separation –Duty cycle Common for all systems: –Transmitter spectrum mask, receiver selectivity –Intermodulation, harmonics, IF, image suppression –Receiver sensitivity, required S/I ratio, transmitter EIRP –Antenna gain and horizontal/vertical radiation pattern –Deployment geometry 3 WRAP 0975C

4. Equipment: Receivers 4 WRAP 0975C

5. Equipment: Transmitters 5 WRAP 0975C

6. FH Interference Table-defined/Table-defined frequency hop set –Determine minimum frequency separation Δf int for non- interference (by iteration) –Determine number of frequencies in the hop set with less than Δf int –Perform for each receiver frequency. Add all numbers of interfered frequencies, divide with total number of frequencies, multiply with transmitter duty cycle –Account for all transmitters that may interfere. 6 WRAP 0975C

7. Table-defined, details 7 WRAP 0975C

8. FF/BH Interference For Fixed frequency/Band-hopping cases –For TX1, sub-band 1, determine Δf int –Determine number of frequencies in sub-band 1 with less than Δf int –Continue with sub-band 2, 3 etc –Add numbers of interfered frequencies from each sub-band, divide with total number of frequencies, multiply with transmitter duty cycle –Form combined interference from all transmitters: 8 WRAP 0975C

9. TH/BH Interference For Table-hopping/Band-hopping cases –As for the Fixed-frequency/Band-hopping case, calculated for all frequencies in the table –Determine interference from TX no. M (n is the number of frequencies in the table) as 9 WRAP 0975C

10. BH/BH Interference For Band-hopping/Band-hopping cases –As for the Table-hopping/Band-hopping case, by re-defining the hop bands to table-defined 10 WRAP 0975C

11. Considered cases In the Interference tool: –Only co-channel/adjacent channels interference In the Collocation Interference tool: 11 WRAP 0975C

12. Result presentation [%] In the Interference tool: –Total interference P intTot –Individual contribution P int from each transmitter In the Collocation Interference tool: –Total interference P intTot –Individual contribution P int from each transmitter –Individual contribution P harmonics etc from each transmitter 12 WRAP 0975C

13. Result interpretation P intTot gives the percentage of time that the interference is higher than the receiver can handle without sensitivity reduction The approximate average number of interference pulses per second can be calculated as Where I Rate :Interference pulses per second f hr :Hop rate, hops/s (same rate for all transmitters/receivers) d:Duty cycle of transmitter [%] 13 WRAP 0975C