18 responses

  1. avatar
    Tim Farrar
    October 23, 2012

    You seem to be rather confused about the Cisco data that you are citing to try and discredit WiFi as a major source of incremental capacity. Cisco’s latest analysis (Feb 2012) assumes that in the US the proportion of handset/tablet mobile data traffic that will be offloaded to WiFi will drop from 49% of total traffic in 2011 to 46% in 2016 (see http://tmfassociates.com/blog/2012/02/14/cisco-building-castles-in-the-air/). Yet the PCAST report notes that already one major US cellular operator is offloading more than 50% of its traffic, and most observers expect this to increase much further. A more realistic assumption, that 80%+ of traffic will be offloaded, would cut Cisco’s traffic growth projections by more than half.

    With respect to your statement that “carriers are deploying and using every single technology and “trick” they can to try to solve the looming spectrum crisis in the near-term”, the CTIA data shows that capex by US operators has not changed significantly in 2011 and 2012 and remains lower in absolute terms than in 2004 (see http://tmfassociates.com/blog/2012/07/12/spectrum-crisis-or-capex-crisis/). Indeed just last week, Verizon noted that it plans to reduce its capex in the next few years – hardly the sign of an operator desperate to deploy “every single technology” it possibly can do.

    Finally, you mirepresent Shannon’s law. That deals with capacity through a given channel, not the total capacity of a given amount of spectrum, once re-use is taken into account. Rather more relevant is Cooper’s Law (http://www.arraycomm.com/technology/coopers-law) stating that wireless capacity doubles every 30 months (and has done for the last 100 years). As noted in the referenced article, of the million-fold improvement in wireless capacity over the last 45 years, only 25 times has come from more spectrum, and 1600 times has come from more re-use.

    • avatar
      John Marinho
      October 23, 2012

      I did not discredit Wi-Fi as a major source of incremental capacity, what I said was that demand is growing faster than the supply of capacity made through carrier deployed spectrum and Wi-Fi combined.

      An assumption that 80% of all traffic on all carriers’ networks being offloaded to WiFi in the US is unrealistic at this time and for quite some time into the future.

      While we can’t comment on the plans of an individual carrier, the fact that carriers adjust their capital expenses plans from year to year is hardly unusual and indeed “every single technology” and “trick” has to do with the fundamental capabilities and capacity improvements possible with available and practical technology rather than the absolute cost spent on the improvement. As we know from Moore’s Law and general market trends – technology provides more capacity at lower cost over time.

      To say that Shannon is not relevant to spectrum is to suggest that spectrum is not used to transmit information. One such example of its use is Shannon-Hartley, which is used to address the minimum possible Eb/No to achieve the maximum possible transmission capacity. Such calculations, as an example lead to the ability to evaluate spectrum capacity.

      On the topic of re-use, in the real world, it is common knowledge that there are practical limits as to how many base stations can be deployed in a given area, be they macro-cells or femtocells. Also, because so much reliance over the past 45 years was on re-use and other technology improvements (1600 compared to 25 as pointed out), the industry had no choice but to mortgage its future to compensate from a lack of additional spectrum.

      Consumer growth in demand has indeed placed a disproportionate burden on the available capacity made possible through re-use and technology – at this point it is time for more spectrum to address the looming crisis.

  2. avatar
    Steve Crowley
    October 23, 2012

    Qualcomm is working on increasing mobile capacity 1000x in the next ten years. They call it the 1000x Challenge. One scenario they have is placing small cells in 9% of homes in a macrocell. In that case, capacity in that cell increases 500x. Doubling spectrum increases capacity 2x. Putting the two together increases capacity 1000x. It gives you an idea of the relative capacity increases that can be had by increasing spectrum versus increasing the number of small cells.

    Another advantage of small cells is that handset battery life is increased because reduced transmitter power is needed for the uplink to reach the closer small cell. Increasing capacity by just increasing spectrum does not decrease handset transmitter power.

    Finally, to the extent more spectrum is made available to mobile broadband, Qualcomm’s research suggests (work continues) that higher frequencies are better for small cells. The supposedly “beachfront” UHF frequencies propagate well, and their interference does too. Interference from higher frequencies does not propagate as far, which may make interference management for small cells easier.

    Regardless, I think spectrum remains one of the key components for increasing capacity, along with advanced network topology (small cells, Wi-Fi, heterogeneous networks) and advanced radio technology.

    • avatar
      John Marinho
      October 25, 2012

      Thanks for your response. I agree completely. The wireless industry continues to innovate and is recognized as the hallmark of efficiency and advanced technology. Without the types of innovations you mentioned, many of the future mHealth, mCommerce or mBanking scenarios may not happen. So to your point, spectrum is key since, for decades, the industry has leveraged technology and innovation to stay ahead of growth in consumer demand for mobility. We’re now at the point where more spectrum is critical to fuel the virtuous cycle of innovation and growth in the connected mobile society of the 21st century. Technical innovation and spectrum availability must work hand-in-hand; you cannot have one without the other – for very long.

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