Steven J. Crowley, P.E.
Archive for the ‘DTV’ Category
“To generalize, it is often true that studies will be promoted that tend to support the policy inclinations of the Chairman, under whose direction, after all, every draft decision is made.”
“[S]tatistics can lie. But cast as ‘studies’ by commentors, they take on the weight that a decision maker chooses to make of them.”
As a follow-on to its National Broadband Plan, the FCC last year released a Technical Paper intended to validate the Plan’s prediction of a 300 MHz mobile-broadband spectrum deficit by 2014. The Paper describes a spectrum requirements model that totals current spectrum assigned to mobile broadband and applies a multiplier based on expected demand, taking into account expected increased tower density and improvements in air-interface spectrum efficiency. The model’s result is a predicted deficit of 275 MHz in 2014, which rounds to 300 MHz. On the way toward that result, however, the analysis uses just a few of the available data forecasts, ignores offloading of macrocell data to Wi-Fi and femtocells, and assumes the continuation of flat-rate plans for consumers. Some of these oddities I noted in a post at the time. I had hoped the FCC would make the Paper a subject of public comment. That hasn’t happened. So, I’ve looked at the Paper in more detail. I find that when looking at the above factors in a more realistic manner, predicted spectrum requirements go down significantly.
A couple of days ago the Mobile Future coalition posted a short video on YouTube advocating the allocation of more spectrum for mobile broadband. As evidence of the need, it says that, compared to feature phones, smartphones use 24 times the spectrum and tablets 120 times the spectrum.
Recent contributions to the mobile broadband spectrum debate are reports from NAB and CTIA. I envisioned a “dueling reports” piece, but they mostly complement each other. Below I walk through the main points, adding some of my own views.
On November 30, the FCC adopted a Notice of Proposed Rulemaking (NPRM) as a preliminary step toward making the current TV broadcast spectrum available for use by fixed and mobile wireless broadband services. The proposed rules would do three things: 1) make fixed and mobile wireless services co-primary with broadcasting in the FCC’s Table of Frequency Allocations, 2) create a regulatory structure giving two or more TV stations the option to share one 6 MHz channel, and 3) improve VHF TV reception through power increases and adoption of receiver antenna standards. No service rules are being proposed; they’re to come later. Congress has yet to approve incentive auction authority.
The FCC’s National Broadband Plan (NBP) recommends that the Commission make available 500 MHz of new spectrum for wireless broadband, including 300 MHz for mobile use. In support of that recommendation, on October 21, the FCC released an FCC Omnibus Broadband Initiative technical paper: Mobile Broadband: The Benefits of Additional Spectrum. The paper concludes that mobile data demand is likely to exceed capacity in the near term and, in particular, that the spectrum deficit is likely to approach 300 MHz by 2014.
The FCC recently issued an order denying reconsideration petitions in its ultra-wideband (UWB) proceeding. That effectively ends the 12-year UWB rulemaking process. Mitchell Lazarus recounts how UWB became bogged down at the FCC and in a failed standardization attempt in IEEE 802.
UWB, as authorized by the FCC, operates across 3.1 to 10.6 GHz, with very low power at any one frequency; its tendency to cause or receive interference is very low.
IEEE 802 attempted to create a UWB standard in IEEE 802.15.3a but did not, as neither of two competing proposals reached the necessary voting threshold for approval. One of the competing proposals, Multi-band Orthogonal Frequency Division Multiplexing (MB-OFDM), has since seen some consumer success in Wireless USB, which is based on a platform maintained by the WiMedia Alliance; data rates are up to 480 Mbps at a range of about 10 feet.
UWB was eventually standardized in IEEE 802.15.4a, where it exists as an alternative physical-layer to standard IEEE 802.15.4-2006, a standard for very low power, low data rate devices. (The IEEE 802.15.3 family is for higher data rates with higher power consumption.) It uses what was the other competing proposal in 802.15.3a, Direct Sequence UWB (DS-UWB). This standardized form of UWB has been commercialized for asset tracking and other location services, but not yet for consumer applications.
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The FCC held its Broadcast Engineering Forum on June 25, 2010.
As background, the National Broadband Plan recommends repurposing 120 MHz of from the TV bands to mobile broadband. On June 14 the FCC released an Omnibus Broadband Team Technical Paper that describes some of the analyses supporting this repurposing. Chairman Genachowski asked the Commission staff to hold the Forum to consider ideas in the Paper.
At this Forum there were four areas discussed:
- Advancements in Compression Technology
- Cellularization of Broadcast Architecture
- Improvements in VHF Reception
- Methodologies for Repacking the TV Band
Each area had been the subject of discussion by groups in workshops earlier in the day. At the Forum each of the four groups reported preliminary findings and recommendations.
After hearing the Forum, which is a preliminary effort, I”d say its gist is that technical changes in the TV industry aren’t going to free up significant TV spectrum for mobile broadband. There are no advancements in compression technology that can be implemented in a timely manner (i.e., less than 13 years). State-of-the-art in compression technology, and market realities, makes channel sharing by different licensees impractical. Cellularization of broadcast architecture is seen as not practical nor economical. There is room for improvement in VHF reception, perhaps through higher transmit power levels and better, smart receive antennas. An examination of methodologies for repacking the TV band shows no scenarios where stations can avoid sharing channels, unless some stations voluntarily go off-the-air. (And, as we heard in the presentation on compression, sharing is seen as impractical.)
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This summarizes a selection of applications for the Experimental Radio Service received by the FCC during May 2010. These are related to WiMAX, sensors, SAW devices, radio-location, ultra-wideband, white space, aircraft passenger communications, landslide monitoring, collision avoidance radar, mobile DTV, LTE, Inmarsat handsets, highway rock-fall monitoring, HF communications, spacecraft link characterization, and interference into broadband access.
- Polytechnic Institute of NYU filed an application (with supporting exhibit) for experimental license to conduct a network research project using WiMAX on 2535-2540 MHz. This is part of the nationwide Global Environment for Network Innovations (GENI) project, a suite of infrastructure that will support experimental research in network science and engineering. GENI is supported by the National Science Foundation and managed by the GENI Project Office at BBN Technologies.
- Mnemonics, Inc. filed an application (with supporting exhibits) for experimental license to operate in support of a research project that is to develop and demonstrate the viability of wirelessly extracting measured data from a network of passive surface acoustic wave (SAW) sensor devices. This sensing technique is said to have several advantages over existing sensors, including no wired connections needed to extract data, no power requirements, operation up to 1000 degrees C., and sensor cost in-quantity in the tens of cents each. Operation will be on 915 MHz.
Television Broadcast reports on the status of 3DTV standards development around the world.
The FCC is working under a Congressional deadline of February 17, 2010 to develop a National Broadband Plan. That work includes looking for additional spectrum for wireless broadband services.
On December 2, 2009, the FCC issued a Public Notice asking for more comment on spectrum licensed to broadcast TV stations, and on market-based mechanisms that would encourage broadcasters to make spectrum available for wireless.
TV broadcasters generally like their spectrum as it is. They argue that over-the-air TV is a public service. It is the only source of video programming for some. A large investment was made in the recent DTV transition. They are working on advanced technologies including Mobile DTV and other content delivery platforms. Multicasting provides greater choice in programming without the need to subscribe to a cable or satellite service.
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