Lessons Learned: Transitioning from TDM to IP

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Cell phone tower near Lozen, Bulgaria. Photo credit: Plamen Agov • studiolemontree.com [CC-BY-SA-3.0 or GFDL], via Wikimedia Commons

The transition from the Time Division Multiplexing (TDM) cell phone networks of the 2G and 3G mobile era has been a long time coming. However, the mobile industry seems to be at one of its proverbial inflection points where IP (Internet Protocol) technology is ascendant and TDM has begun the long but inevitable decline into legacy status.

Aviat Networks has been there all along the way, helping operators design and deploy aggregation systems. We’ve seen and learned a lot as some of the leading mobile phone carriers have upgraded their networks. Now as LTE works its way into mainstream status, cell phone networks are transitioning to full-IP, the underlying technology of LTE. Continue reading

60GHz Band: a Solution for Small Cell Backhaul?

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Small cell will enable mobile usage in dense urban environments but will need a backhaul solution to make it possible. Photo credit: Ed Yourdon / Foter / CC BY-SA

The Case for Small Cell Backhaul
As the search for frequency bands with suitable capacity for small-cell backhaul continues, frequency bands above 50GHz start to appear attractive because they offer both high-bandwidth availability and short range owing to their inherent propagation characteristics. The white paper available at the bottom of this blog examines spectrum in the 57-64GHz range to see whether it can be of use for small cell backhaul.

In many countries, the frequency range 57-66GHz is split into a number of discrete bands with differing requirements and conditions of use and/or licensing. These differences will be highlighted where applicable.

From a global point of view, the use of this spectrum by Fixed Services (FS) is being addressed by the ITU-R in its draft report on Fixed Service use trends in WP5C, which is currently under development and states:

57 GHz to 64 GHz
The radio-frequency channel and block arrangements of these bands for FS are defined in Recommendation ITU-R F.1497.
In 2011, around 700 links were in use in this band in a few administrations. The majority of the links are used for fixed and mobile infrastructure.
The air absorption around 60 GHz is over 10 dB/km. This condition restricts the hop length; on the other hand, the spectrum reuse efficiency is high. This feature makes the band suitable for small cell mobile backhaul.

Clearly, a global reported usage of 700 links would suggest a great deal of underutilization, although with unlicensed use in many countries it is difficult to know whether these figures are accurate or not. Regardless, there are reasons as to why this could be the case, while noting that the ITU-R believes this band has potential for small cell backhaul.

One factor is that this spectrum is not allocated solely to the Fixed Service. In fact, in many countries the Fixed Services have no access to this spectrum at all. A more detailed country-by-country breakdown follows. Please sign up below to receive the entire white paper.

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Ian Marshall
Regulatory Manager
Aviat Networks