LTE TDD, or the “Time Division Duplex” variant of 4G LTE, has been steadily gaining momentum over the past year or so. The number of commercial deployments has surpassed 10, and 36 more are either in commercial roll-out or trials. There are signs that not only are a number of greenfield LTE operators considering LTE TDD, but also by a number of incumbent mobile cellular operators.
One of the reasons for the interest in LTE TDD has been the commitment to support both LTE TDD and FDD on the same chipset for mobile devices. It should help to drive economies of scales for mobile device production for both operator deployments. But there is an additional dimension: LTE operators may even secure blocks of spectrum for FDD and TDD LTE operation within their own market. Why? Because a mobile operator can use LTE TDD, and FDD, to expand coverage and/or capacity within their own network.
SK Telecom, in conjunction with Ericsson and Altair Semiconductor, has developed handover technology that confirms handover between FDD LTE and TD-LTE can be as seamless as handover on single FDD mode between different bands. LTE TDD, instead of being a bit-part player on the 4G stage may be rapidly evolving into playing a major supporting role.