Last Friday, 03 August 2012 saw the release of FCC Report and Order 12-87, which contained some significant changes that will lower the total cost of ownership for many microwave links. The two most significant changes concern antenna sizes and wider bandwidths.
Following lobbying by Comsearch and the Fixed Wireless Communications Coalition (FWCC), within which Aviat Networks plays an important role, the FCC has allowed an additional alternative set of antenna parameters to be used in the 6, 18 and 23GHz bands. These new parameters are an alternative to the existing antenna parameters, which have been retained. It is worth noting that while the FCC does not specify actual antenna sizes, the realization of antennas based upon these new parameters does represent a reduction in size and thus provides for the reduced cost of both CAPEX and OPEX that has already been championed by Aviat Networks and other interested parties. The new working alternative antenna parameters are as follows:
- 3 feet for the 6GHz band
- 1 foot for the 18GHz band
- 8 inches for the 23GHz band
To put these changes into perspective the typical cost of renting space for an antenna on a tower is US$400 + US$100 per foot (diameter) per month. So a link consisting of two 6ft antennas will cost 2x (400 + 6×100) = $2000 per month, i.e. $24,000 per annum.
If the antenna diameter could be reduced to 3 feet the cost is reduced to 2x (400 + 3×100) = $1400 per month, i.e. $16800 per annum—a saving of $7200 per year on a single link!
The above calculations are not only ours but also those of MetroPCS, which is quoted in the report and order. MetroPCS specifically notes, as an example, that “the cost of a microwave dish antenna is approximately $100 per foot per month. Thus, even if the revised rule allows for a reduction of just one foot, the annual savings would be $1,200, and the savings over a ten year period would be $12,000.”
Smaller antennas also open up more options in terms of locations for these antennas, and their smaller size reduces wind loading and the need for specialist mountings and strong towers.
Additionally, the FCC in a further notice of proposed rule making attached to this report and order seeks feedback on allowing similar alternative antenna parameters in the 11 and 13GHz bands. Aviat Networks intends to support this proposal via the FWCC.
With the ever-growing demand for bandwidth the FCC has decided to allow aggregation of two 30MHz channels in the 6GHz band and two 40MHz channels in the 11GHz band, giving maximum bandwidths of 60MHz and 80MHz, effectively allowing a doubling of the capacity of a microwave link. This represents another significant cost saving because this increased capacity can be achieved with the same amount of hardware.
Also in this report and order were changes to the definition of efficiency standards to a bits/sec/Hz standard as proposed by the FWCC, and a clarification of the definition of payload capacity: “The bit rate available for transmission of data over a radiocommunication system, excluding overhead data generated by the system.” The FCC has also introduced a welcome simplification of the rules with regard to bit rate efficiency. FCC Part 101.141 has been amended to include a table (below) that details the efficiency criteria according to two frequency ranges and three bandwidth ranges:
Aviat Networks welcomes the FCC’s progressive changes as the amendments will stimulate the microwave industry and enhance the cost effectiveness of microwave networks across the United States. We expect the rule changes to be effective approximately in October.
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