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February 15, 2012

Will Heterogeneous Networks Actually Happen?

By Dr. Alan Solheim, VP of Marketing and Business Development, DragonWave Development , DragonWave Inc.

The continued demand for data-rich mobile applications continues to drive up the required mobile network capacity. Mobile network operators are struggling to keep up with this demand and are deploying new radio access technologies such as HSPA+ and LTE (News - Alert), buying additional spectrum, using off-load techniques such as WiFi hot spots and introducing tiered pricing, all in an attempt to increase the network capacity and moderate the consumer demand. These efforts still fall short and many experts are proposing reduced cell size as the most effective mechanism to increase total network capacity.

Small cell architectures increase the network capacity by deploying many more radio access points, each with roughly the same capacity of a single sector macrocell but much more closely spaced, thereby reducing the number of users per cell and giving each user a larger portion of the total cell capacity. In order for small cell architectures to deliver the capacity gain while reducing the cost per bit required to enable the mobile operators to deliver new services economically, we need a new type of microsite design, one that integrates all the required functions such as radio access, power conditioning, backhaul, environmental enclosure into a single aesthetically pleasing package that is easily deployed, and at a cost that is at least an order of magnitude lower than the equivalent macrocell.

Many companies are hard at work developing solutions that solve the above challenge. The macrocell base station providers are pushing to reduce the size, cost and power of their base stations or introducing new architectures that use distributed radio heads with centralized base band processing. New entrants are extrapolating designs that were originally intended for femtocell applications into more powerful outdoor capable designs, sometimes with integrated WiFi (News - Alert) for additional capacity. Meanwhile, the backhaul vendors are creating new and smaller products with varying degrees of integration. While all of this innovation is encouraging for the overall small cell market, one has to wonder how it will all come together.

Traditionally, mobile operators have only used a single radio access vendor in a given market in order to simplify the back office functions, such as network management and billing, to ensure smooth handoffs between base stations for mobile users and reduce the training and spare equipment required for the operations and maintenance personnel. For similar reasons, usually, but not always, a single microwave vendor is used in a given market for the backhaul. As we deploy small cells, WiFi offload and other techniques, the challenge for co-ordination and selecting the best network resources becomes much more complicated. For example, should a handset connect to the nearby WiFi access point, which has good signal strength but is owned by a local coffee shop and may or may not be congested with other users, or should it connect to a small cell or even to the macro network? Which connection is lowest cost? Which is highest performance? Who decides and on what basis?

Although the network standards do attempt to specify the interfaces sufficiently well that multiple devices from multiple vendors can interoperate, in practice, small variations in the implementation mean that some degree of interoperability testing must be done to ensure smooth operation. On top of this, in order to differentiate themselves, many vendors go beyond the standards and develop features that add value but do not work with other vendor’s equipment. For the data plane, the standards are reasonably well developed, but as we go further up the network stack, other functions such as network management, billing, trouble tickets, etc., all require a higher degree of adaptation to include a new vendor’s equipment into the network. This creates an environment where is it relatively easy for the incumbent vendor to throw up roadblocks to the new entrants or, said another way, incent the mobile operator to limit the number of different vendors they include in their network.

There are very few examples anywhere in telecom networks where multiple different vendors co-exist in a single network. Even in IT networks where the degree of interoperability is perhaps more advanced, IT departments usually limit the choices simply to reduce maintenance and improve purchasing leverage on a smaller number of suppliers. All of this seems to point to an environment where natural business practices will impede the rapid adoption of some of the more innovative capacity enhancing techniques, and that most of the smaller vendors will need to align somehow with the larger incumbents, potentially reducing the overall level of innovation offered to the customer since incumbent vendors will be reluctant to cannibalize their existing offerings with new ones. On the other hand, mobile operators are motivated to make the early adoption of new technologies happen in order to drive overall network cost reduction and capacity improvement. Whether or not heterogeneous networks become a reality or single vendor networks continue to be the norm remains to be seen. If nothing else, it will be interesting to watch how these competing forces resolve themselves.

Dr. Alan Solheim, Vice President of Product Management at DragonWave, is author of TMCnet�s The Middle Mile column. To read more of Alan’s articles, please visit his columnist page.

Edited by Rich Steeves
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