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      On Wall Street Low Latency Microwave Fulfills Faster than Fiber

      Happy Holidays and Happy New Year from all of us at Aviat Networks. Just as you are finishing those final gifting ideas for the winter, we would like to share a few thoughts from Travis Mitchell, Aviat Networks director of low latency business development. In the just published article “Microwave Technology for Low Latency Trading Networks” in Wall Street & Technology, Travis clears up the misconceptions that trading technologists may have about microwave communications, many of which have carried over from the age of analog radio and do not apply to digital microwave.

      In addition, Travis spells out the advantages that low latency microwave has over fiber optic technology. Two of these are the point-to-point, direct line-of-sight communications between microwave stations and the absolute higher speed microwaves can achieve. In comparison, fiber communications oftentimes do not run directly from Point A to Point B but must instead wind their way around obstacles, burrow underground, climb tall buildings and so on before reaching their destination. This extra distance covered contributes delay to the overall latency experienced by trades sent via fiber as compared to microwave.

      Then the immutable laws of nature tell us that microwave communications—even traveling through the atmosphere—approach very close to the speed of light. On the other hand, laser communications traversing the dense medium of fiber optics are much slower than the speed of light—many tens of percentage points slower than the speed of light.

      To close, Travis briefly summarizes other factors that go into making low latency microwave networking the choice for traders over fiber, including minimizing the network route, maximizing the distance between microwave hops and using passive repeater technology, when appropriate. For the whole story, see the article. Other resources also include our low latency microwave white paper and low latency webinar replay.

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      Developments in Fixed Link Spectrum Access in Ireland

      spectrum

      Spectrum (Photo credit: Free Press Pics)

      In response to the ever-growing demand for spectrum to satisfy the increase in usage of data hungry mobile applications and in line with recently published ECC recommendations, ComReg (i.e., Ireland’s telecom regulator) issued a consultation document looking at the future demands on spectrum for point-to-point fixed links. September saw the publication of the conclusions and subsequent decisions arising from that consultation, to which Aviat Networks was the only manufacturer to respond. This blog highlights some of those decisions:

      New Spectrum
      One of the major topics was the requirement for more spectrum allocated for point-to-point usage. Consequently, ComReg has made the following announcements:

      • ComReg intends to open the frequency bands below, as there is a significant demand for fixed links services in the 28 GHz, 31 GHz and 40 GHz band:ComReg microwave spectrum rules change September 2012
      • The 32 GHz band may be made available for fixed links services at a later stage subject to its potential for future PP/PMP use and the demand on spectrum for PP use in the 31 GHz (31.0 – 31.3 GHz paired with 31.5 – 31.8 GHz) band
      • Within the 28 GHz band, as per REC T/R 13-02 Annex C, the following frequency ranges will be made available for fixed links services: 27.9405 – 28.4445 GHz and 28.9485 – 29.4525 GHz
      • Frequency bands 28 (27.5 – 29.5) GHz, 31 (31.0 – 31.3 paired with 31.5 – 31.8) GHz, 32 (31.8 – 33.4) GHz and 40 (40.5 – 43.5) GHz will not be opened for PMP use in the current spectrum strategy period 2011 – 2013

      Aviat Networks supported this initiative during the consultation process and is pleased to see ComReg make these announcements as a move to satisfy the increasing demand for microwave spectrum. Specifically, frequencies in the range of 28 to 42 GHz are ideal for short-haul urban links, and we expect the decision by ComReg to stimulate further growth of microwave for fixed line and mobile network applications.

      Technical Changes

      • High-Low search radii for the 23 GHz and 26 GHz bands will be reduced from 200 meters to 100 meters. The consensus of current licensees operating within the 23 GHz and 26 GHz bands is that the reduced radius will improve spectrum planning and reuse, which will improve spectral efficiency
      • There will be no distinction between rural and urban areas concerning the High-Low search radius
      • Antenna size will be limited to 0.6 meters in the 23 GHz and 26 GHz bands
      • ComReg will allow use of 56 MHz channels in the 26 GHz band only where the licensee has a National Block license containing contiguous blocks of spectrum
      • ComReg will permit the use of higher bandwidths, as shown in the table below, to facilitate the increase in mobile data demand:ComReg microwave spectrum rules changes September 2012

      Block Licensing
      ComReg signalled its intention to potentially reopen the 26 GHz block license scheme for a further round of National Block assignments, subject to market demand. In the past, Aviat Networks commented that it believes block licensing is not the most appropriate method of licensing in the microwave bands. However, ComReg disagrees with that view.

      Summary
      The combined expansion in spectrum use—new bands and larger channel allocations—underlines the popularity and ongoing viability of microwave as an alternative to fiber in urban networks experiencing rapid traffic growth and geographic expansion.

      Aviat Networks welcomes the ComReg announcement. We already address all the band/channel assignments made by ComReg.

      Ian Marshall
      Regulatory Manager
      Aviat Networks

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      Wireless Regulators Move to Prevent Spectrum Waste

      Historically, in many countries the 26GHz and 28GHz wireless frequency bands have been allocated to point-to-multi-point systems, such as LMDS in the United States and LMCS in Canada. However, most of these systems have failed to reach their expected potential in terms of revenue generated and, as such, much of the allocated spectrum is now unused. This, along with the growth in demand for point-to-point microwave spectrum, has meant a number of national regulators have started to consider reallocation of this spectrum.

      In Canada, the spectrum allocations for both the 26GHz and 28GHz bands have been revisited, owing to their underutilization by LMCS operators, with a new band plan having been developed during the drafting of SRSP 325.25. The diagrams below show the new allocations that accommodate more FDD spectrum suitable for microwave in point-to-point usage.

      Figure 1 - 25.25 - 26.5 GHz Band Plan and Associated Usage - Industry Canada

      Figure 1 – 25.25 – 26.5 GHz Band Plan and Associated Usage – Industry Canada

      While the technical details of this draft SRSP have been finalized, consideration of licensing options by Industry Canada has so far delayed the formal publication of this SRSP. Note that the remaining point-to-multipoint operators are catered to in the TDD section in the middle of the 26GHz plan.

      Figure 2 - 27.5-28.35 GHz Band Plan and Associated Usage - Industry Canada

      Figure 2 – 27.5-28.35 GHz Band Plan and Associated Usage – Industry Canada

      In the Republic of Ireland, ComReg (the Irish national telecommunications regulator) recently issued a consultation resulting from an operator request to change the use of its allocated spectrum from point-to-multipoint to point-to-point. Figure 3 shows the current situation in Ireland and Figure 4 shows the same band after the proposed change of use.

      Figure 3 - Current 26GHz Band Plan - ComReg Ireland

      Figure 3 – Current 26GHz Band Plan – ComReg Ireland

      In the United States, the LMDS service occupies the following spectrum blocks:

      • 27.5 – 28.35 GHz
      • 29.1 – 29.25 GHz
      • 31.075 – 31.225 GHz
      • 31.0 – 31.075 GHz
      • 31.225 – 31.3 GHz

      Thus, that would make a total of 1300MHz of spectrum—more than double the recent allocation at 7 and 13GHz—potentially available across the entire country. LMDS take up has been very low, and, as previously mentioned, much of this spectrum is now unused. This begs the question: Would spectrum reallocation in the U.S., as is happening in Canada and Ireland, promote its more active usage?

      Figure 4 - Revised New 26GHz band plan - ComReg Ireland

      Figure 4 – Revised New 26GHz band plan – ComReg Ireland

      It is worth noting that existing users are protected in both the examples given above, but unused spectrum is now available to point-to-point operators. Therefore, it is now time to approach the FCC and request a similar exercise to be carried out for the United States. Aviat Networks intends to be one of the driving forces in requesting this reallocation of spectrum.

      Ian Marshall
      Regulatory Manager
      Aviat Networks

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