Connecting the Unconnected: GSM and UMTS Spectrum Overlapping Technology - Mobile World Live

Connecting the Unconnected: GSM and UMTS Spectrum Overlapping Technology

19 DEC 2016

PARTNER FEATURE: Mobile broadband (MBB) has changed the world. It’s so involved in our lives that sometimes we forget that more than half of the world’s population does not have access to MBB. In the global effort to connect the unconnected, operators have proposed a wide range of schemes to help bridge this divide.

Most of the MBB unconnected population are in emerging countries, where people are sensitive to data tariff and handset prices. With better coverage foundation and device penetration, 3G networks are suitable for taking more responsibilities. Additionally, many subscribers here who own a 3G-compatible handset have no access to a 3G network. Estimates suggest the number of 3G smartphones without data connectivity could be as high as 20 percent. Providing internet networks for such people is also an important market for operators.

Complications can arise when attempting to create extra space in a pre-existing structure. This isn’t limited to telecommunications, but also city planning, where decisions must be made, such as whether to buy some new land or re-use the old roads to build a highway. Spectrum resources require the same analysis. In order to build a ubiquitous 3G network, spectrum resources must be with good coverage characteristics and support a large number of devices. The most easily accessible spectrum is low band spectrum (900MHz), which is considered scarce and allocated to GSM networks already. Therefore, operators need to find new, inventive way to create space.

For city planning, new land for new roads is too costly. Replacing or repairing old roads will cause traffic congestion and ultimately an unhappy society. According to the spectrum utilization rules in the radio access network (RAN), dedicated spectrum is required for each radio access technology (RAT). This restriction makes building a new network faced with the same dilemma as city planning. Operators obviously can’t countenance switching off GSM when so many customers and machines are reliant on it. To provide basic GSM capacity and a new UMTS single carrier, 6.2MHz is needed in the 900MHz band: 2.4MHz for GSM and 3.8MHz for UMTS. Currently, 15% operators whose 900MHz spectrum band width is between 5-6MHz are out. For operators whose 900MHz spectrum is wider than 6.2MHz, preventing GSM user experience from dropping during refarming is an obstacle. Sudden GSM spectrum reduction will cause severe congestion. At the same time, UMTS is likely to be light-loaded and its spectrum underutilized.

To solve such spectrum problems, Huawei introduced its [email protected] solution at the Global Mobile Broadband Forum 2016.

[email protected] solution breaks the restriction of dedicated spectrum for multi-RATs by using Multi-RAT Spectrum Overlapping. This solution has GSM and UMTS spectrum resources overlap, offering flexible ways to use GSM and UMTS into a given spectrum. This is ideal for the 15% operators whose 900MHz spectrum bandwidth is between 5-6MHz, since [email protected] enables GSM&UMTS just in 5MHz bandwidth as its name shows. What’s more, with this solution, rapid coverage of UMTS service is possible because allocation of spectrum resources is flexible and can change according to the GSM and UMTS traffic variation. For example, within 5MHz spectrum, operators could retain two carriers for each GSM cell when 2G traffic is high and reduce to one carrier when 2G traffic is low. Neither switching off GSM nor fast user migration is necessary. Additionally, operators can smoothly and gradually migrate GSM traffic to UMTS and phase out the GSM network.

Huawei reported that [email protected] solution needs minor alterations to be available. Legacy devices and core network are supported and do not need replacing, offering a well-performing MBB wireless network at a very low cost. Though only recently rolled out, [email protected] solution has already been deployed in Nigeria and India with satisfactory results.

[email protected] solution removes difficult challenges of MBB network development. With its spectrum efficiency improvement and capacity flexibility, operators can use this solution to connect the unconnected.


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