commenttofcconnewspectrumforbbwireless

Comment to FCC on New Spectrum for BB Wireless

1. What is the ability of current spectrum allocations to support next-generation build-outs and the anticipated surge in demand and throughput requirements?

The current allocated band of 2110-2170 MHz will not be adequate for next-generation build-outs. Let us consider a channel width of 5 MHz and a raster of 200 KHz, then the throughput would be about 12 Mbps for a 10 db SNR (Signal to Noise Ratio) .This is no where near cable or DSL speeds. Even if the next-generation technologies improve the S/N ratio with spectral efficiency, not much can be done when the signal to noise ratio is so low at the cell edge that throughput will be low regardless of the technology.

OFDM air interface is the key for next-generation technologies, but power intensive. OFDM's advantage really shows up at wider channels. To allow for wider Channels, a large contiguous block of spectrum is needed. A 100MHz increase of bandwidth could be beneficial for the next-generation technologies as it would bring the throughputs comparable to Wired Networks. It could be a long term measure before the spectrum allotment can be revisited.

2. What spectrum bands are best positioned to support mobile wireless broadband?

It depends on the antenna configurations and of course the speed that an individual customer might see as impacted by the vehicle motion as well as other users on the cell since it is a shared network and the terrain associated with that. It could be anywhere within the theoretical limits, as long as there are blocks of broad contiguousbands of spectrum, it gives the opportunity to simplify the network or flatten the network and allows mitigating nearby band interference.

3. What spectrum bands are best positioned to support fixed wireless broadband?

Fixed wireless broadband can be best served with additional allocations in 1710-1850 MHz spectrum (this is between the Met Satellite and the PCS bands). Since it is adjacent to the existing PCS bands, Network design could be more easily achieved. Below 1.7GHz the antenna sizes increase and the power requirements become heavy.

4. What are the key issues in moving spectrum allocations toward their highest and best use in the public interest?

Licensed spectrum is a premium and it needs to be optimized by some of the following measures:

Underutilized spectrum should be diverted to other users periodically. If a Licensee to a spectrum has not deployed compatible technologies for that market, that spectrum should be deemed as underutilized and this spectrum need to be shared with another vendor.

Wireless broadband is not a competitor for wired broadband in Metro markets. Channel utilization, whether it's Cable, DSL or Wireless is determined by the SNR and wireless can never achieve the same SNR as Wired. Wireless should be considered for mobility aspect alone.

The amount of spectrum needed to make wireless broadband compete with wired broadband is more than 10 folds. To allocate that much amount of bandwidth for broadband wireless is simply not possible. It would disrupt emergency and other essential communications.

Fixed Wireless broadband should always considered be an overlay technology for Metro markets. For Rural markets, if there is no infrastructure, ireless Broadband Wireless can be a Primary choice.

Current spectrum allocation is not in proportion to demand. Command and control, military, emergency, maritime set aside, priority should be assigned to Broadband wireless. Life saving technologies like Telemedicine and Telenavigation could be the main benefactor's for Broadband wireless. Media and Entertainment come along.

The key issue is allocating large contiguous blocks of spectrum. It could be anywhere within the theoretical limits. With Software Defined Radio technology and Electronics for making multi band phones cheaper, spectral regions are not as important.

Rural markets should not be tallied by the same spectral efficiency and link budget issues as the mass markets (Mobile data usage)

Spectrum usage should not transcend national boundaries. Technologies aren't mature enough to allow a safe roaming free environment yet.

5. What is the ability of current spectrum allocations to support both the fixed and mobile wireless backhaul market?

One of the clear problems that is going to abound is literally hundreds of thousands of cell sites because of the need to aggressively reuse the spectrum and provide capacity at an unprecedented rate. That means a huge backhaul problem. At present, Bulk of the Wireless backhaul traffic is still carried by T-1s and T-3s which is expensive. Backhaul can also be solved by the advancements in Wireless Technology.

Utilities companies can also greatly benefit by wireless backhaul technologies as they move the OAM functionality to an all IP technology.

In view of the above 2 requirements, backhaul need to be allocated a significant bandwidth. It need not be contiguous spectrum because it doesn’t have the same propensity for interference as at the actual customer level. Even paired bands will be sufficient as long as there is sufficient bandwidth.

- Narasimha Vadrevu

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