Internet has evolved to send a much greater proportion of traffic down to the user relative to the amount of traffic sent back up to the Networks. The rapid rise in demand for high-bandwidth applications, such as online video and gaming, have accelerated the proportion of downstream traffic on the wired Internet to as much as 90%.
For many decades, regulators across the world have generally licensed spectrum in paired bands, whereby 50% of the spectrum was allocated to the downlink and 50% was allocated to the uplink. These allocations made sense in the “old world” of wireless in which 2-way voice was the predominant use for the spectrum.
In the new world, mobile broadband is the primary driver of traffic growth and most of the traffic consumption is flowing downstream from the network to the mobile device, which is similar to the wireline experience. This is a huge shift for network traffic management from carriers that grew up in a symmetrical voice world. We have also learned that mobile operators have taken actions to try to improve the downlink throughput relative to the uplink, including the upcoming deployments of MIMO antenna technology. However, these technology efforts will likely reach their limits quickly and carriers will likely need a lot more spectrum dedicated to the “downstream” or “downlink,” as mobile broadband traffic growth continues.
Two More Solutions to Address the Problem of Asymmetrical Mobile Broadband Bandwidth
Under spectrum aggregation techniques, carriers can add unpaired spectrum bands in nonadjacent frequency bands to augment the amount of downlink spectrum available within the network. Carriers are likely to leverage the spectrum aggregation capabilities that we understand are embedded into the upcoming LTE standards that allow carriers to attach unpaired spectrum for downlink within its network architecture.
Carriers could try to change the direction of some of the uplink spectrum into downlink spectrum. However, we have learned that such a move could create meaningful interference issues that could limit the efficiency of its own spectrum or interfere with the adjacent spectrum bands used by its competitors. Operators can switch technology flavors from FDD (Frequency Division Duplex) to TDD (Time Division Duplex). FDD technology uses paired spectrum bands, whereas TDD technology includes the uplink and downlink segments within the same spectrum band. TDD technology allows the carrier to dynamically allocate the amount of the spectrum used for uplink and downlink. However, a carrier trying to use the spectrum with a TDD technology within spectrum bands that use FDD technology can create interference for possibly other carriers. Is the TRAI listening ?