User's Manual

U-NII Config & User Guide 5.2 Axxcelera Broadband Wireless
13.6 RF Channels spacing and output power
Channel Center Freq EIRP
# (GHz) (dBm )
-----------------------------------------------
0* 5.17 19
1* 5.185 19
2* 5.2 19
3* 5.215 19
4* 5.230 19
-----------------------------------------------
55.2726
65.28526
75.326
85.31526
95.3326
-----------------------------------------------
10 5.745 32
11 5.76 32
12 5.775 32
13 5.79 32
14 5.805 32
15 5.820 32
16 5.835 32
-18.5dB
-18.5dB
Low Band * Indoor Only
Middle Band
UNII & ISM Frequency Spacing
for AB-Access 5-6GHz
Band Edge
Guard
5.7605.745 5.775 5.790 5.805
5.8505.725
5.820 5.835
-18.5dB
High Band
5.35
5.25
5.2855.27 5.3 5.315 5.33
5.1855.17 5.2 5.215 5.230
5.25
5.15
13.7 TDD (Time Division Duplex)
The AB-Access system uses TDD (Time Division Duplex) to transfer data across the
wireless link as opposed to FDD (Frequency Division Duplex). The AB-Access implementation
of the TDD architecture allows the TDD frame to dynamically vary in size according to the
offered load: short frames when fewer users are sharing the channel, longer frames when there
are many simultaneous users. The TDD guard time is also adaptive, as it is set to round trip
propagation delay to the farthest SU. TDD has a number of advantages over a FDD system.
These include:
• Spectral Efficiency – TDD can be deployed using less spectrum than a comparable
FDD system. A single TDD channel can be deployed per sector instead of two
channels needed for FDD. Likewise, a multi-cell deployment can be installed using a
total of three RF channels (both polarizations), whereas FDD needs four to six
channels.
• Complexity – Since each transceiver is wither transmitting or receiving, but never
both at once, a single RF front end can be shared reducing the radio complexity.
• Power Control – In cellular systems, where channels are reused many times
throughout the system in order to increase capacity, the highest efficiency is realized
when the power in each direction can be minimized. This reduces the amount of
March 10, 2003 Company Confidential Page 132 of 149