Netops, members, and interested parties of PSDR and
Memphis,
I propose the following changes to our official band plan
for point to multipoint:
- Elimination of the 5 MHz and 20 MHz channel width standards
- Introduction of a second set of sector channels
- Introduction of channels specifically to be used for omni use in areas where sectors are not feasible (user density, space, budget)
- Adoption of dual chains, horizontal and vertical, for the last mile
See a chart of the proposed band plan here: https://jsfiddle.net/ryan_turner/n13cy7ot/4/embedded/result/
I propose these changes in order to address a number of
issues:
- 5 MHz channel width is not particularly beneficial; its performance improvements are only marginal over 10 MHz, and it is a rare scenario for this to be useful in a last mile situation. Frequently signals that benefit from 5 vs 10 MHz would be much further improved by instead better client antenna positioning. 5 MHz channels may be reasonable temporarily should we place them somewhere within an unoccupied 10 MHz channel, but today as the two 5 mhz and 10 mhz plans coexist, they overlap and interfere.
- 20 MHz channel width is not likely to be adopted locally due to marginal nature of all of our links and the limited benefit from the afforded bandwidth. I do anticipate hardware limitations may drive us to eventually use 20 mhz channels, however.
- Since our antenna systems are not ideal radiators, inter-cell interference remains a problem for sites that have LOS between eachother; two of our sites today are able to see eachother entirely -- that is to say, each sector on one can see all five other sectors; introducing more channels for this scenario would greatly help
- In dense urban areas and areas where towers and tall buildings are specifically banned, in order to reach our users we need more frequent, smaller points of presence
- Dual chain radios have already been deployed at
multiple sites and found to be better performing than
the slightly higher output power mikrotik metals; cell
site sector antennas already support dual polarity,
and with Mikrotik's mANT30 dish the end-user cost
difference is about $40 over our current day
recommended solution.
Please share your thoughts and opinions.
Thanks,
-- Ryan Turner,
K0RET
+1.901.300.0039
+1.901.300.0039
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