NSN supports gradual GSM refarming
Spectrum constrained carriers can move to 3G or LTE in gradual stages, boosting flexibility and cost efficiency
Published: 8 May, 2012
While some operators are rolling out mobile broadband in brand new spectrum, many can only make an early move if they reuse existing holdings, a complex business. Nokia Siemens, which is sharing T-Mobile USA's major modernization contract with Ericsson, is showing off a system to enable gradual migration of GSM frequencies, turning off legacy networks one at a time.
The vendor has announced two innovations to maximize the efficiency of refarming 2G spectrum. The first is Energy Efficient Coverage (EEC), which uses similar techniques to MIMO smart antenna arrays, to enable existing GSM frequencies to support up to twice the amount of traffic. Alternatively, it can achieve the same GSM performance using less bandwidth, freeing up more frequencies for refarming, making it quicker and cheaper for the operator to achieve strong HSPA coverage.
The second breakthrough is Configurable Carrier Bandwidth (CCB) for W-CDMA. This allows 3G bandwidth to be set in software configurable increments of 200KHz, from the very narrow 3.8MHz up to 4.2MHz, depending on the cellco's spectrum holdings. This offers greater flexibility to allocate GSM frequencies for refarming to HSPA or LTE as they become available. The capability also supports colocation of GSM and W-CDMA on the same band for operators with very limited spectrum, since refarming can kick off with a W-CDMA roll-out in just 3.8MHz. As GSM traffic decreases, more can be freed up and the 3G bandwidth increased to 4MHz or 4.2MHz.
The two new software features will be available commercially, on NSN's SingleRAN multi-technology network platform, in the second half of 2012. NSN will clearly have an eye on its new refarming deal with TMo, though the issue is also becoming important in Europe and Asia, where some cellcos have missed out on the coveted sub-1GHz digital dividend licences for LTE. This has helped to shift attention in GSM refarming away from HSPA migration, with more firms looking to leap straight to 4G.
"Mobile spectrum is scarce, and operators want to maximize the GSM spectrum they can refarm to W-CDMA and LTE," said Dhruv Khanna, NSN's head of sales development for mobile broadband in north America. "Operators can refarm using much narrower spectrum than before, deliver GSM and W-CDMA with 30% less spectrum, and also lower total cost of ownership by 20%. Moreover, they can deliver a vastly improved user experience, and potentially attract more customers to increase revenues."