Dynamic Spectrum Refarming with Overlay for Legacy Devices
01 October 2013
The explosive data growth is resulting in a spectrum crunch forcing many wireless network operators to look toward refarming their 2G spectrum and deploying more spectrally efficient Long Term Evolution (LTE) technology. However, Mobile network operators face a challenge when it comes to spectrum refarming because 2G technologies such as GSM is still widely used for low bandwidth machine-to-machine (M2M) devices. M2M devices typically have long life cycles, e.g. smart meters, and it is expensive to migrate these devices to newer technology since a truck roll will typically be required to the site where a device is deployed. Furthermore, with cost of 2G modules several times less than that of LTE, even newly deployed M2M devices adopt 2G technology. Nevertheless, operators are keen to force their 2G M2M customers to migrate so that they can refarm the spectrum. In this paper we propose a novel solution to provide GSM connectivity within an LTE carrier through an efficient overlay by reserving a few physical resource blocks for GSM. With this approach, operators can refarm their 2G spectrum to LTE efficiently while still providing some GSM connectivity to their low data rate M2M customers. Furthermore, spectrum can be dynamically shared between LTE and GSM. An approach similar to that proposed in this paper can also be applied for other narrow band technology overlays over LTE.