Could multiple spectra RAN multiply benefits?

A long term objective of next generation wireless networks is to shift to a more adaptive, unified wireless link and network architecture that provides a framework for a range of deployment scenarios, from basic broadband access for low density rural, to multiple services including high broadband media in high density urban environments.

A practical way to achieve the broad range of requirements is to use a combination of low and high frequency spectrum bands on a best connected and best use basis. This can be summed up as 'purpose use of spectrum.'

Multiple frequency band RAN development and deployments are soon to emerge, but will take several years to reshape the nature of wireless networks.

Individual benefits

The benefits of each spectrum have thus far been extolled independently: the lower, sub 1GHz frequency bands, such as 700, 800 and 900MHz have been cherished for their long range and ease of building penetration.

The higher frequency spectrum, particularly the less technically exploited 'broadband spectrum' including 2.3 to 2.5, and 2.6GHz bands, seen as attractive for WiMAX and LTE, are able to deliver very high bandwidth using MIMO and beamforming 'smart antenna' technologies and micro-cell deployment architectures.

However, each of these is a less than ideal way to organize a multiple service IP communications network. What if the virtues of low and higher NLOS, (non-line of sight), frequency bands were used as best matched the bandwidth, range, penetration, subscriber density and other factors justified in order to deliver best performance per cost?

And what if deployments could be scaled adaptively as demand evolved? These are possibilities that are magnified by the core wireless link interface of WiMAX and LTE.

Today the antenna and RFIC component suppliers claim they can deliver the multiple band antennas needed for 2X2 MIMO mobile devices in 700, 800, or 900MHz plus a corresponding 2.3 to 2.7GHz band.

Multiple spectra RAN

One way to achieve flexibility and service capacity of next generation wireless service is to develop multiple spectra RAN. A large coverage footprint is needed to drive down unit costs of the uniquely designed infrastructure and subscriber devices.

While this has been conjectured and advocated by Maravedis for several years, it is recently seeing the light of day in plans for a multiple spectra RAN in Sweden. Some details of system design are available from likely LTE multi-spectra RAN suppliers including Alcatel-Lucent and Ericsson. The Tele2 and Telenor 900 MHz plus 2.6GHz MSRAN network is not expected to be widely deployed for another three years, so details of potential handsets are not likely to become available just yet.

A new research paper explores the coverage, business models, and range of applications and impact on current business and competitors that will develop as the Verizon LTE and Clearwire WiMAX networks roll out.  Additional interviews are being conducted over the next two weeks.

Further discussion and links to related articles and publications can be found at: