Could LTE replace WiMax?

Many WiMax operators today are exploring the opportunities that LTE offers,
either as a complementary technology or an alternative to WiMax. Three
developments have compelled this re-evaluation of 4G strategies.

Firstly, the growing support for a time division multiplexing (TDD)-version
of LTE, TD-LTE, has created a more direct competitor to WiMax which uses this
spectrum. Interest in TD-LTE has spread with many mobile operators attracted by
the opportunities for international roaming and cheaper spectrum.

Secondly, vendors have introduced platforms that support multiple air
interfaces through software upgrades, and plan to commercialize multimode
devices. The lower cost and complexity of migrating to a new air interface makes
it more attractive for WiMax operators to switch to LTE or to support both 4G
technologies.

Thirdly, with a larger market size and commitment from tier-1 mobile
operators, a powerful LTE ecosystem is building, with a wider choice of devices
and competitive equipment prices. Key factors for WiMax operators to consider
when assessing their options include services offered-LTE will be more
attractive to WiMax operators that target mobile broadband subscribers, giving
them access to a wider choice of mobile devices, and facilitating roaming;
spectrum availability-WiMax operators have the flexibility to deploy LTE using
TDD or frequency division duplexing (FDD) spectrum bands, while WiMax equipment
is limited to TDD; growth-WiMax operators may decide to roll out LTE as a
replacement for WiMax, or as a complementary technology that provides additional
capacity and facilitates new services; timeline -WiMax operators may wait until
the LTE ecosystem is more developed to reap the full benefits of transition and
minimize its costs. It is equally important for operators to consider service
continuity within the core network and full service portability.

The transition to LTE must be transparent to subscribers. Service plan
features, billing, application and bandwidth management, and provisioning must
be consistent as subscribers move from WiMax to LTE. This is even more important
if WiMax and LTE coexist, because subscribers will frequently switch among
interfaces and should be able to do so without noticing any change in their
service.

For these reasons, a smooth transition of the control plane in the IP core,
including subscriber data management, policy control, and service control is
crucial.

For a swap of WiMax for LTE, a software upgrade of common modules will
suffice. If the two networks need to co-exist, two core networks have to be
established, but some elements can be shared.

The similarities between WiMax and LTE, the streamlined upgrade process, and
the pressing need to respond to steep mobile data traffic growth have made it
possible for a new breed of operators to emerge-the 4G operators.

David Sharpley

The author is senior VP,
Bridgewater Systems

vadmail@cybermedia.co.in