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Easy fix to GSM capacity crunch

By Vishal Agnihotri on Fri 13 June, 2014

This blog is by Vishal Agnihotri  from the Networks business of Nokia.
Twitter: @v_agnihotri

One of the key factors behind the exponential growth of data traffic has been the rapid increase in the number of smartphone users. 2013 was the year when the smartphones outsold the feature phones (non-smartphones) for the first time. For most operators, coping with the explosion in data traffic is matched by the challenge of continuing to serve existing voice traffic using the same capacity and infrastructure. In the past, the answer was to simply add more sites and carriers to meet rising demand for capacity, but this is not always viable because of the sheer pace of growth in demand and the huge amount of new hardware and site infrastructure that would be needed. On top of that, space constraints and local regulations often do not allow such expansions.


One South American operator experienced a similar situation: the operator’s GSM network was running out of capacity, but the lack of space at most of its sites prevented any significant capacity expansion.

Nokia effectively addressed this challenge with our Orthogonal Sub Channel-Half Rate (OSC-HR) solution. Based on a simple software upgrade, it can double the voice capacity of existing GSM sites by allowing them to carry up to four voice calls in a single voice channel (radio time slot), without adding any new carriers, sites or additional hardware. Existing voice traffic in the network can now be served with fewer radio channels, thus freeing up spare capacity that can be used for data services. Alternatively, the increased capacity and improved efficiency can be used to re-farm GSM spectrum for 3G HSPA / LTE deployments.

OSC-HR works with SAIC-capable handsets (Single Antenna Interference Cancellation) and on average, more than 65% of the handsets in the networks are SAIC-capable.

Initially deployed by the South American operator in a given cluster in the network, the impressive field performance of OSC-HR verified the potential benefits. The existing voice traffic can now be served with fewer channels, resulting in 10% more capacity available for data services. The field performance of the feature convinced the company to deploy OSC-HR across the whole network, covering thousands of base stations.

Nokia’s OSC-HR solution has already been delivered to over 90 customers worldwide.

We have more to share on Nokia’s innovative GSM software capabilities here.

Find out how to serve five times more smartphone users in GSM – with a simple software upgrade here.

To share your thoughts on the topic, join the discussion with @NSNtweets using #NSNperformance #GSM #smartphone #3G #HSPA.


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  1. Bhadran Fri 13 June, 2014

    Its cool..awesome !!!

  2. Fahad N. Wed 20 August, 2014

    Hi ,
    can you elaborate OSC impact in terms of RF load ?


    • Ritva Siltanen Mon 1 September, 2014

      Hi Fahad, and very sorry about the delay in replying.

      This is what Vishal Agnihotri says:

      “Compared to AMR-HR that pairs 2 voice calls in 1 time slot, OSC-HR pairs up to 4 voice calls in 1 time slot depending on radio (RF) conditions and some user defined thresholds. Good radio conditions, for eg, over 12db C/I would mean more pairing- more calls to be paired for OSC- and hence more OSC calls. this translates into more traffic per TRX (carrier) or in other words, improved spectral efficiency

      OSC is especially helpful in addressing congestion as it reduces the traffic channel blocking by up to 72%”