1. Adjacent Channel results for Four Channels
IEEE /365
May 2002
May 2002
Adjacent Channel results for Four Channels
Steve Halford
Michael Seals
Mark Webster
Steve Halford, Intersil
Steve Halford, Intersil Corp

2. Background Doc 02/220r0 proposed optional Channel 0
May 2002
Background
Doc 02/220r0 proposed optional Channel 0
Allows for 4 20 MHz channels at 2.4 GHz
Presented in March Meeting (St. Louis)
Two phone conference held to discuss
Channel spacing closer than .11b
Spacing same as a
5 GHz has many more channels
Can layout channel re-use to avoid adjacent channels
4 channels is insufficient to avoid adjacent
Forbidden Band is also 5 MHz closer
Will require more back-off to meet
Steve Halford, Intersil

3. May 2002
Simulation Model Used
Steve Halford, Intersil

4. Spectral Control via Masks
May 2002
Spectral Control via Masks
TGg Draft Spec allows for two different mask
Both masks are relative to peak of the main lobe
Picture of Masks
Steve Halford, Intersil

5. Power Amplifier Model P_sat= 24.2 dBm P_1dB = 21.5 dBm May 2002
Steve Halford, Intersil

6. ACI Results ACI increases with narrower spacing
May 2002
ACI Results
Waveform
Power out (dBm)
ACI
(dBm)
ACR (dB)
Channel Spacing (MHz)
Limit
OFDM
19.91
-6.53
26.43 20
.11a Mask
QPSK
20.35
-12.36
32.71
.11b Mask
-12.66
32.57 25
-19.39
39.74
ACI increases with narrower spacing
OFDM increases by 6.13 dB
PSK/PBCC increases by 6.73 dB
What impact will this have on performance?
Steve Halford, Intersil

7. Forbidden Band Results
May 2002
Forbidden Band Results
Waveform
Power out (dBm)
Back-off 1-dB
(dB)
Channel Spacing (MHz)
Distance to FB
(MHz)
OFDM
11.11
10.39 20 17
QPSK
16.05
5.45
15.95
5.55 25 22
18.83
2.67
PSK/PBCC modes will need 2.78 dB more back-off
OFDM modes will need 4.94 dB more back-off
Steve Halford, Intersil

8. Conclusions & Questions
May 2002
Conclusions & Questions
Narrower spacing increases interference
From 6.73 to dB increase over existing ACI
Forbidden Band compliance is possible
Additional Back-off required
QPSK: dB
OFDM: 4.94 dB
Is this level of interference acceptable?
Is 4-channel the best approach to getting more channels?
Ex: 8-channels are possible using half-rate clocks
Steve Halford, Intersil