On offload, 4G Americas says Wi-Fi offload of mobile traffic is at 35% today in the U.S., and is estimated to be 68% by 2016. There’s no source for these numbers, such estimates can vary, but these figures are reasonable.

Absent is a similar consideration of femtocell offload, but it can be expected to be smaller than that for Wi-Fi up to 2016, at least.

4G Americas then has an interesting paragraph on Cisco forecasts of mobile data growth:

Cisco’s VNI data on global mobile data traffic (Figure 23), which makes no distinction between historical and forecasted data, yields vastly different projections depending upon how much of the historical record is included in the fit. The following graphic shows the impact of selecting pre-2012 data points (in blue) and including Cisco’s own forecast to 2015. We see, then, that we live in a critical time, when the wireless data explosion is upon us, but its further outlines are only hinted at in current data. Careful analysis of the traffic statistics in the coming quarters may reveal the 2015 and 2020 expectations or perhaps see the unleashing of further pent-up demand.

So, 4G Americas apparently combines measured results pre-2012, and Cisco VNI data for 2012 and beyond, then fits a logistic curve (sometimes called an S-curve) to these data, which shows global growth “saturating” around 2020 at about 13 exabytes per month. The “critical time” refers to us possibly being at an inflection on the curve. We might be there because the year-to-year growth of Cisco’s forecast is decreasing. (Put another way, the percentage increase is smaller each year.) I suggested this is what is happening in a blog post last November. For anyone skeptical, look at any Cisco VNI forecast and calculate the year-to-year percentage increases.

The blue curve shows the infamous “exponential growth” curve, which continues to be invoked as a spectrum bogeyman, especially in the U.S; as you can see, no way. The red curve is a logistic curve fit to a 2.5x growth rate, which appears high compared to the green curve fitted to Cisco data.

This is just one scenario. Perhaps, as 4G America’s suggests, there will be an “unleashing of further pent-up demand.” We don’t know what’s going to happen, but this result is consistent with the transformation of mobile networks from macrocell-only to heterogeneous — bringing the user closer to the “base station,” which will increasingly be a small cell indoors because that’s where we are most of the time. When this happens, the user is offloaded from the macrocell, and demand on the macrocell is decreased. We’ll be using ever-increasing amounts of data, but it will be accessed more efficiently, with smaller percentages from macrocells. Regardless, this projection should not slow efforts to make spectrum policy more rational and spectrum use more flexible.

Looking at the chart, we see the U.S. has the most subscribers of the countries chosen for comparison (China and India each have about three times as many subscribers as the U.S.).  Then we see that the U.S. average revenue per voice minute, which can be considered a proxy for subscriber cost, is 4 cents, the lowest of all countries compared. Very impressive. I’ve seen criticism that this figure may be lower than actual because of a possible assumption that the consumer uses all, and no more of, plan-minutes per month. Even with further adjustments I’d expect the comparison to be favorable. With the growing role of mobile data services, data costs would be a useful to see as well; such a comparison is conspicuous by its absence.

CTIA then positions the U.S. as a leader in efficient use of spectrum, by a factor of two-to-one or more, using “Subscribers Served per MHz of Spectrum Allocated.” Here, they lose me. Cellular spectrum is reused. We are not partitioning the spectrum allocations such that each subscriber has a unique fraction. Though there are many ways to measure spectrum efficiency, and new ones can be created, I don’t see how this qualifies.

We’re back on track with the last two lines showing spectrum allocations and new spectrum in the pipeline.  I’m concerned that they are based in part on “regulatory and company websites and press reports.”  As we have seen, some press reports are more reliable than others. I’d like to see the specific reference for each figure.

I find it noteworthy that Japan and South Korea, nations with very progressive wireless industries, make do with less spectrum than the U.S. It may be no coincidence that South Korea has one of the smallest spectrum allocations, one of the smallest amounts of spectrum in the pipeline, and has operators that are aggressively deploying Wi-Fi offloading and six-sector base-station antennas, which nominally double spectrum capacity compared to the more-common three sector antennas.

The 50 MHz pipeline figure apparently comes from the National Broadband Plan. There’s been a lot of spectrum policy activity since then, but we’re agreed that there’s little in the pipeline now. In my next post I’ll try to take a snapshot of where we stand with the usual spectrum candidates, and suggest one or two others. Later I plan to review where we are with offloading and other technologies, along with tiered rate plans, that can reduce, but not eliminate, the need for new mobile broadband spectrum.

Gerald Whitney filed an application with exhibits for experimental license to test a prototype AM broadcast transmitter system covering 2-16 MHz at a carrier power of 1 kW. The system, part of a U.S. Department of Defense project, includes a frequency-agile transmitter, antenna tuning unit, and antenna. Testing will be done in Victor, New York.

Curtis-Wright Controls filed an application with exhibit for special temporary authority to demonstrate its 3d-Radar brand of ultra-wideband ground penetrating radar (GPR) for prospective non-federal customers as it awaits expected FCC grant of its Part 15 waiver request for the device. Operation will take place at various locations in the U.S. on 140-3000 MHz, with frequency notching to preclude transmissions in the bands 608-614 MHz, 1400-1427 MHz, 1660.5-1668.4 MHz, and 2690-2700 MHz, in accordance with an NTIA authorization. The company filed its Part 15 waiver request with the FCC in June 2010 seeking authorization to operate the device for non-federal use (ET Doc. No. 10-167). The company understands the FCC’s Office of Engineering and Technology is working on an order that would permit non-federal use of the device. The company notes that NTIA, with FCC coordination, has already approved the use of the device for federal use on a nationwide basis.

Carlson Wireless Technologies filed an application with exhibit for special temporary authority to test voice and data connections among multiple Chevron Oil oil-field facilities using TV white space frequencies. Test results will be compared to the performance of a current 900 MHz system. Operation will be at several California locations in the 174-216 MHz and 470-698 MHz bands.

Southern Methodist University filed an application with exhibits for experimental license to operate a cognitive radio testbed. The testbed is backed by a National Science Foundation grant.  Operation will be on several frequency bands between 400 MHz and 6100 MHz in the Dallas area. The testbed will be used to study wireless performance in mobile and stationary environments. Featured in the testbed is real-time multi-band operation, which can be used to aid design of context-aware and cognitive algorithms that use multiple frequency bands to adapt to dynamic environmental conditions. One goal of the research is to develop an open-access database of wireless performance in multiple scenarios.

L3 Nova Engineering filed an application with exhibits for experimental license to demonstrate a seismic activity sensor network. Testing will take place in Great Falls, Virginia on 420-440 MHz.

Sierra Nevada Corp. filed an application for special temporary authority to test equipment that will facilitate formation flight between two aircraft. This supports DARPA’s Global Hawk autonomous aerial refueling demonstration program that is intended to accomplish the first-ever fully autonomous rendezvous, refueling, and formation flying of two unmanned aircraft. Each node of the system consists of a GPS receiver, processor, and other equipment including the UHF data link that is the subject of this application; one node would transmit data to the other such that the receiving node would be able to calculate its position and orientation relative to the transmitting node. The testing will take place in Salt Lake City, Utah on 420.25-426.60 MHz.

Raytheon BBN Technologies filed an application for special temporary authority test distributed-transmit beamforming using RF modules developed under DARPA’s Precision Electronic Warfare (PREW) program. “Specifically, BBN Technologies seeks to demonstrate the capability to synchronize clocks from up to 10 RF modules remotely using UHF band frequencies, and project RF energy at specified frequencies that results in the coherent combining of focused power within a small geographic area of interest using the these radios to enable high data rate transmissions and longer ranges.” According to DARPA, “the goal of the Precision Electronic Warfare (PREW) program is to demonstrate technologies and a prototype system that will enable the fielding of an ad hoc sparse array consisting of multiple airborne and/or ground nodes that can perform surgical jamming. The PREW system should be able to project RF energy that results in the coherent combining of focused power within a small geographic area of interest (AOI). When operating outside the AOI, the system must minimize the coherency of the RF energy to limit the impact to collateral systems.” Testing will occur at Sky Meadow State Park, Delaplane, Virginia on 437-493 MHz, 877-953 MHz, and 2400-2480 MHz.

Airvana filed an application with exhibit for experimental license to develop and test prototype LTE infrastructure equipment on 698-716 MHz, 728-757 MHz, 776-787 MHz, 806-824, MHz, 851-869 MHz, 1910-1915 MHz, and 1990-1995 MHz. Airvana says it will evaluate handoff performance among sectors, network capacity, quality of service, multi-path performance, average data rates, and interference performance. The testing is to take place nationwide.

Lockheed Martin filed an application with exhibits for experimental license to conduct testing in support of the Extended Area Protection System (EAPS) missile test program under sponsorship of the U.S. Army. The EAPS interceptor is a small ground-launched missile system under development as a performance demonstration program of hit-to-kill technology. The hardware requiring licensing consists of two systems. The first is the telemetry system providing downlink of flight telemetry data from the interceptor to a launch control trailer. The second is the unmanned ground system that provides uplink of flight control data from the launcher control trailer to the interceptor. Testing will take place in Texas on 2270.5, 2280.5, 2281.5, 4401.5, 4410.5, and 4411.5 MHz.

Bell Helicopter Textron filed an application with exhibits for experimental license to conduct testing and development in support of eventual unmanned helicopter flights. Testing will take place in the vicinity of Arlington, Texas on 2282.50 MHz.

Teletronics Technology Corp. filed an application with exhibits for special temporary authority to test a new transceiver with both OFDM and burst-mode shaped-offset QPSK (SOQPSK). The transceivers are said to provide “maximum transmission and reception distance under harsh environmental conditions.” Operation will be in the vicinity of Newtown, Pennsylvania on 2360-2390 MHz.

North American Eagle, a project testing the capability of a land-based vehicle to safely transition through supersonic speed, filed an application and exhibits for experimental license to operate a Wi-Fi network consisting of five Tropos model 7320 mesh routers mounted on eight-meter towers and one Tropos model 4310 mobile-mesh router mounted in the vehicle’s nose cone. Video and vehicle operational data will be sent to the base stations. Operation is to take place on dry lake beds near Black Rock, Nevada and Diamond Valley, Nevada on 2400-2483MHz (for data) and 5725-5850 MHz (for video). Transmitter output power will be 30 watts. (Wi-Fi at 800 MPH will be a challenge.)

Raytheon filed an application with exhibit for special temporary authority to test a critical-infrastructure-protection radars system. The system uses a 90-degree-quadrant staring radar with moving target indication designed for perimeter intrusion detection applications around secure facilities such as airports, seaports, utilities and other critical infrastructure. The system is based on Raytheon’s SR1500 Short-Range radar, which is under development. The plan is to deploy a network of low-power, short range (1.5 km) radars at fixed locations around critical infrastructure sites of the Port Authority for New York and New Jersey to provide perimeter security. An Ethernet-based network provides communication between multiple radar and electro-optic sensors. Testing will take place at various locations around New York City on 3100-3500 MHz.

L3 Communications filed an application and exhibits for special temporary authority to test a SONAR telemetry transmission system for military use. The system would send SONAR data from a small boat at a rate of 10 Mbps. The link will also carry video from cameras on the boat to allow operators to confirm normal operation of the hardware. The SONAR data and video will be transmitted to a larger manned ship at a range of a few miles. Testing will take place on the Pacific Ocean, between San Pedro and Catalina Island, in the bands 5200-5679 MHz and 5689-5800 MHz.

Laufer Wind Group filed an application with exhibits for experimental license to conduct tests in connection with the development of a radar-activated FAA obstruction lighting system for wind farms. Testing will take place in New York and New Hampshire on 9380-9440 MHz.

Lockheed Martin filed an application with exhibits for special temporary authority to evaluate Ku-band satellite technology for high-data-rate communication to helicopters. It intends to test ViaSat’s proprietary technology said to maintain the flow of data transmission in the presence of momentary path blockage from rotor blades. Test antennas will be mounted on stands underneath the rotor blades. Testing will be in Owego, New York on 14.0-14.5 GHz.

Raytheon filed an application with exhibit for special temporary authority to test a radar system for mobile surveillance system based on the DRS MSTAR commercial-off-the-shelf radar. The radar, in conjunction with electro-optical/infrared cameras, is intended for use in monitoring international borders. Testing will take place near McKinney, Texas on 16.75-17.25 GHz.

General Dynamics filed an application with exhibit for experimental license to operate an airborne radar system in support of ground imaging research using synthetic aperture radar techniques. Separate transmit and receive antennas would be mounted to a rotational pedestal on the underside of an aircraft. The gain of the antennas is 40 dB at 94 GHz, and they have a 1.5 degree half-power beamwidth in both the azimuth and elevation planes. The radar will use a pulsed linear-FM chirp waveform, centered at 94 GHz with a bandwidth of 600 MHz. The width of the waveform pulse will be approximately 20 microseconds and operate at a pulse repetition frequency of approximately 10 kHz. Peak ERP will be 5,000 Watts. Operation will be in the vicinity of Ypsilanti, Michigan.

Ducommun LaBarge Technologies filed an application with exhibits for experimental license to test its model SG-DDR50 security system, a directed-energy weapon that uses millimeter-wavelength energy to “stop, deter, turn back, and otherwise discourage a trespasser, thief, or belligerent and threatening person at relatively long distances.” “The system consists of an electrical power source, a device producing millimeter wavelength electromagnetic energy, an energy director projecting a narrow energy beam towards a target, and mounting and connecting equipment.” “The SG-DDR50 uses the susceptibility of skin nerve endings to millimeter-wavelength electromagnetic energy to report a sensation of intense undesirable heat on the skin of the person in the energy beam, all while doing no harm.” “The purpose of the experimental license is to align the system to operational specifications using infrared imaging of patterns on a sensitive carbon impregnated teflon [sic] target . . ..” Testing will occur in Huntsville, Arkansas on 94.5-95.0 GHz. Transmitter power and ERP are both specified as 800 Watts on the FCC application form. According to the applicant, “[t]he nature of this test configuration does not lend itself to be characterized by traditional measures, such as ERP, ERIP, Peak Power, and the like.”

To your point, I don’t see LTE being competitive with wired in terms of speed or reliability today or in the future. You take the hit there for the convenience of mobile or portable operation. There’s a notion that if we just add enough base stations and repurpose enough spectrum to LTE, we can replicate the home wired experience in the mobile environment, but I don’t think that’s practical. The throughput from an LTE sector is divided among all users in the sector. If everyone wants to watch the Super Bowl at once on LTE, forget it (unless the LTE broadcasting standard is implemented, which let’s everyone watch the same channel like today’s TV (cough)). On FIOS or cable, the Super Bowl is no problem.

Moreover, video streaming on LTE is and will be a pain because of the need to maintain a relatively constant bit rate in a fading radio environment. An inordinate amount of system resources go into doing that, and the tiered rate plans we are seeing being adopted are in part a response to discourage that.

A twist is Wi-Fi, which can exceed wired data rates (or, at least somewhat match the speed of the wire it’s connected to). Many smartphones have Wi-Fi and, again, the tiered plans are to encourage you to use Wi-Fi whenever possible. In a year or two I think there will be more deployment of 3GPP’s Generic Access Network standard, that allows seamless switching of the phone between LTE and Wi-Fi — the core network can’t tell, and doesn’t care, which one it’s using. When you stream Netflix, it will switch to Wi-Fi by itself if available. With most smartphone use indoors, I think most smartphone access to the operator could one day be through Wi-Fi, with LTE as a backup for when on the move.

A 3G feature phone on Verizon’s network uses about 1.25 MHz of spectrum. Using the above multipliers, a smartphone would need 30 MHz and a tablet 150 MHz, more than the total spectrum inventory of some carriers. In reality, smartphones and tablets use the same 1.25 MHz. What’s going on?

I assume the numbers Mobile Future cites come from the latest Cisco forecast (p7), but those are for increases in data traffic, not spectrum. Mobile Future seemingly equates the two, but they’re different. Data traffic increases with smartphones and tablets, but that data takes up capacity in existing spectrum. At some point, that spectrum runs out of capacity. More spectrum, along with other techniques, can be used to add capacity.

I sense the hand of a PR firm in this, which means it wasn’t cheap. Fortunately, the error seems confined to the voiceover, which can be redone relatively easily. To be breezy about it, for the sake of a two-minute video, the revised message might be that spectrum capacity is limited, smartphones and tablets use much more, when we run low performance suffers, more spectrum adds capacity improving performance.

Wireless service rationing? Millions of new jobs? Hey, it’s an advocacy video. I’d be very pleased if this video drew more attention to spectrum issues, and did not contribute to the myths.

NAB – Shortages of Capacity, Not Spectrum

The NAB report is prepared by Uzoma Onyeije, a consultant who was once Broadband Legal Advisor to the Chief of the FCC’s Wireless Telecommunications Bureau. The main claims are that there is no need for an urgent and massive reallocation of spectrum, that there are numerous alternatives to spectrum that can boost network capacity, and that sources of spectrum other than TV are more readily available.

It starts by noting there wasn’t a “spectrum crisis” until the American Recovery and Reinvestment Act of 2009, which required the FCC to promote broadband access. The National Broadband Plan followed calling for 500 MHz of spectrum to be made available for broadband within 10 years, with 300 MHz of that for mobile within five years, and 120 MHz of that to come from television broadcasting. Seven months after concluding that 300 MHz was needed in the short term, the FCC released a Technical Paper intended to support the 300 MHz figure. In November I wrote on that Paper, pointing out several factors not considered that, had they been, would have acted to reduce the estimate of short-term spectrum requirements. Later, I questioned the appropriateness of the FCC relying on a forecast prepared by the marketing department of an equipment vendor, without critically and openly examining the assumptions that went into the forecast. Onyeije shares some of the concerns I had, and still do, with that Paper.

I expect the American Recovery and Reinvestment Act turned some spectrum wants into needs, but by all accounts mobile network data volumes are increasing significantly, fed by a volatile mixture of old flat-rate plans and new bandwidth-hungry devices, though the growth rate of those data volumes is decreasing. Getting additional spectrum is a natural option to consider for more capacity. Onyeije provides a list of non-spectrum options. Some have been mentioned here before – offloading to Wi-Fi and other technologies, adjusting rate plans so largest data users pay more, tighter software coding of applications and operating systems. I don’t think I’ve discussed channel bonding, which is a technique that uses non-contiguous spectrum – combining a sliver here and a sliver there. Support for this will be appearing in LTE-Advanced, going on the air in a few years. Backhaul is also something I haven’t focused on; how much of the current spectrum crunch is really due to backhaul bottlenecks?

Another capacity-increasing technique mentioned is sectorization – changing a non-directional transmission system to a directional one using two or more sectors at the same cell site. In the most congested urban areas in the US, antenna systems are generally configured with three sectors, with each sector 120 degrees wide. You don’t see many six-sector configurations, in which each sector is 60 degrees wide. Theoretically, that doubles capacity from the same tower. A long time ago there was more activity in six-sector antenna systems, but the sense then was it wasn’t too practical; you might end up with just a 70% capacity increase because of real-world issues such as imperfect antenna patterns. It was hard to justify the expense. These days, however, with better transmission technology, it should be looked at again. I note SK Telecom in Korea is deploying 500 six-sector sites, after good results with 20 test sites.

Onyeije looks at the spectrum warehousing issue. If an operator has spectrum that isn’t being used, but is on track to build it out, I’m fine if it is fallow for a year or so. Maybe longer if the delay is to wait for much more efficient transmission technology that is on track in the standards process. If it is just sitting there with no build-out requirement and no prospect for utilization, I’d think the operator’s investors would create pressure to sell it. If a spectrum holder has “no plans to sell, lease or use” its spectrum, to quote one in Onyeije’s report, I’m more concerned.

Aside from the warehousing issue, Onyeije identifies a few bands that have been languishing at the FCC for years and makes the point that, since they have been idle for so long, the spectrum crisis must not be so great. These are the AWS-3 spectrum at 2155-2175 MHz, H block spectrum at 1915-1920 MHz and 1995-2000 MHz and J block spectrum at 2020-2025 MHz and 2175-2180 MHz, 700 MHz D block at 758-763 MHz and 788-793 MHz. What’s the story there?

Onyeije suggests mandatory receiver standards. Receivers are already very good in mobile broadband because of vendor competition and the need to operate in a congested environment. Receiver design is proprietary and an important source of differentiation among vendors. I’d think continued improvement of receiver performance in the marketplace, in the long run, would achieve greater capacity benefit than imposed government standards.

The report calls on the FCC to complete and publicly release a comprehensive spectrum inventory, along the lines of the Snowe-Kerry RADIOS Act, which includes measurements. The FCC has made available several spectrum tools online, including LicenseView and the Spectrum Dashboard, which it says is its inventory. According to their disclaimers however, LicenseView “is not intended for analysis of spectrum utilization or spectrum holdings of licensees” and “the FCC makes no representations regarding the accuracy or completeness of the information maintained in the Spectrum Dashboard.” Regarding federal spectrum, I’d add that an inventory becomes more important in light of GAO’s report on NTIA processes that said “NTIA cannot ensure that spectrum is being used efficiently by federal agencies” in part because “NTIA’s data collection processes lack accuracy controls and do not provide assurance that data are being accurately reported by agencies.” Thus, “it is unclear whether important decisions regarding current and future spectrum needs are based on reliable data.”

CTIA , CEA, and WCAI dismiss the NAB report, saying it’s a stalling tactic and they know these things already. One of Onyeije’s points, however, is that it’s the Commission that needs to know these things, and fully investigate and quantify the impact of all capacity-generating alternatives. It has not. It tried with the Technical Report, but inadequately.

CTIA Establishes the Efficient Properties of Cellularization

The CTIA report is intended to demonstrate that US mobile wireless providers are “extremely efficient” in their use of spectrum. The report was prepared by Peter Rysavy, a consultant known in wireless circles for his series of technical reports, with many pertaining to spectrum, air-interface, and mobile device issues.

This report seems to be a response to an NAB claim, some time back, that broadcasting is a more efficient user of spectrum than wireless. I presume NAB’s claim is based on broadcasters’ DTV system transmitting about 19 Mbps in a 6 MHz bandwidth, while the wireless operators are sending about 10 Mbps in 10 MHz bandwidth. (So, TV has more bits per Hertz.) This is kind of an apples and oranges comparison, but the comparison has been made and we have this report in response. Having spent a lot of time in 3G and 4G standards battles, I have no doubt that those participating are trying wring out all the efficiency that is both possible and practical. Wireless standards groups sweat to get another tenth of a dB improvement. Of course, part of efficiency is an implementation issue and not covered by standards. I agree cellular services are more efficient at delivering unicast traffic. Broadcasters, however, can be more efficient in another way. The efficiency debate occurs in part because we have not agreed on a definition of efficiency. More on this below.

The CTIA paper starts with a section on spectral efficiency. It discusses its fundamental measures and technologies that have been used to continually improve it, including adaptive modulation and coding. (Rysavy says his list of technologies is not exhaustive, but to his list I’d add Hybrid Automatic Repeat Request as a key enabler.)

Rysavy observes that the industry’s technologies are operating close to the Shannon Bound, the theoretical limit on the spectrum efficiency that can be had for a given signal-to-noise ratio. Capacity improvements thus must come from advanced antenna techniques (such as MIMO) and topology evolution (e.g., adding picocells to a macrocell).

The report is hopeful on the prospects for Wi-Fi and femtocells to relieve traffic on the macro-cellular network. I’m somewhat more cautious on the potential of femtocells to relieve the capacity crunch.  For various reasons, including interference management, what I think may happen with femtocells is that they get pulled out of the home and put up in neighborhoods using existing structures for support. (The more-favorable pole-attachment rules recently adopted by the FCC are timely.) There are many small-cell trials underway but I haven’t seen much in the way of results.

Network evolution is discussed in a larger sense, focusing on developments in heterogeneous networks, but Rysavy says that’s not enough and that more spectrum is needed, too.

Back to the efficiency issue, the efficiency of cellular systems is compared to that of broadcast television. The point made is that if you take many small cells and place them within a larger area  covered by one transmitter (e.g., one for TV), the cellular system can deliver many times the unique bits in that area. This is true, if that is the definition of efficiency. Let’s look at it another way and compare the maximum number of users served by each scheme. As a best-case scenario, assume the cellular users are using a low-bit-rate application such as LTE VoIP. In 10 MHz we can support about 400 users. That times 3 sectors is 1,200 users per cell. That times 30 cells (as per the example in the paper) is 36,000 users that can be supported at once. In contrast, a TV  station covering the same area can support an unlimited number of users, albeit one-way, since it isn’t limited by uplink capacity nor MAC addresses. Is it a fair comparison? No. One is broadcasting and the other is cellular. Can’t cellular broadcast also? Yes, but to the extent it does the unique-bits argument becomes weaker. We can go around and around. The television example is used, along with other analysis in that section, in an attempt to persuade the reader that “cellular architectures represent a configuration that is capable of providing tremendous service capacity to its users.” I’m convinced, but I was before reading the report.

Rysavy depicts how voice minutes, message volume, and data volume have increased on cellular networks over the years. Yesm growth has been dramatic, but the growth rate is slowing.

Epilogue

Concurrent with this debate, ATSC is in the early stages of planning and developing the second DTV standard to replace the current one that’s been around for about 15 years. LTE specifications support broadcasting, which can be done in a cellular manner on the same frequency. Transmissions are synchronized so the terminal can combine energy from multiple sites. The broadcasters looked at cellularization a year ago assuming use of the current ATSC DTV standard, and rightly found it was not practical. It just wasn’t designed for that purpose. With the new LTE standards, it’s time to look at TV cellularization again but with LTE as a core technology. There could be a return path, inexpensive chips for receivers, and it might  be able to be done in less than 100 MHz, making over 200 MHz available for auction. With DTV, the broadcasters found significant deployment and operating costs with cellularization, but with LTE infrastructure would be shared; it remains to be determined if it’s a business. The technology is there; it just has to be architected by broadcasters and infrastructure vendors into suitable form.

UPDATE 5/20/2011

The FCC issued a Public Notice today seeking comment on using the 2 GHz bands identified as “languishing” by NAB. Some are listed above. 75 MHz total.

Enabling an HD streaming service will be challenging because of the relatively-high and somewhat-constant bit rates required in a fading radio environment. Wondering how practical this is, I recalled a paper Motorola prepared last year reporting some of its simulation results on mobile broadband streaming video.

In one set of simulations, Motorola assumed a 10 MHz bandwidth LTE system with 2 transmit antennas at the base station and 2 receive antennas at the mobile terminal. It assumed video was the only traffic. It tried four different video rates, each under three different deployment cases. (Deployment cases are separate assumptions for frequency, distance between base stations, path loss, and speed of user motion.) The results are shown below.

The left axis shows sector video capacity. This is the total video data downlinked from a base station sector. At a video rate of 256 kbps, the sector capacity reaches a maximum of about 10 Mbps; this means 40 users could be accommodated with individual streams.

Unfortunately for the HD proponent, sector capacity starts to fall quickly as the video data rate is increased. This is because it’s proportionately harder to guarantee a constant stream of data as the rate goes higher. An increasingly inordinate amount of system resources goes into keeping higher-rate streams up over a fading radio channel. This isn’t readily apparent unless one performs dynamic system-level simulations using realistic video traffic models and a detailed model of the LTE air-interface, as did Motorola.

Let’s make an aggressive assumption of 1 Mbps per HD viewer (think high-resolution, but not-so-good quality, video on a notebook or tablet). The sector capacity drops to about 5 Mbps, accommodating five users. One can try trading off HD bit rate and number of users, but there’s little room to maneuver. Motorola didn’t look at 2 Mbps video, but looking at the figure, one might be down to one user per sector at that point. Going the other way, at 512 kbps I might get 20 users, but that’s not HD by any standard or convention of which I’m aware.

Interestingly, in addition to seeing sector capacity drop at rates above 256 kbps, Motorola also saw it drop below 256 kbps. It says this because of overhead in transport and network protocols, and because of constraints imposed by LTE control overhead that put a limit on the maximum number of simultaneously scheduled users.  With 128 kbps per user, one could serve 60 users, which is more than the 40 users for 256 kbps. As Motorola observes, however, 256 kbps is likely optimal to maximize streaming-video revenue for the LTE operator, taking into account both video quality and number of users.

There is overlap between the people who prepare the forecast and the people responsible for marketing Cisco’s line of core-network hardware to service providers. The forecast is used to help sell that hardware. Put simply, it’s a sales brochure. For business purposes, that’s fine. We look at marketing materials all the time, get useful information from them, consider the source, and make a decision. In spectrum policy, we’re not doing that. We’re taking Cisco’s claims as-is, and not considering how the company’s interest in selling hardware might influence its forecast, let alone critically and openly examining the assumptions that go into the forecast.

The Commission should rely more heavily on two forecasts in its possession that, unlike Cisco’s, are independently prepared. One is by Yankee Group and the other is by Coda – both independent research firms. These two forecasts are cited, along with Cisco’s, in the FCC’s October 2010 Technical Paper, Mobile Broadband:  The Benefits Of Additional Spectrum. A chart from the report comparing three forecasts is shown below.

As with any sales pitch, whenever you hear a spectrum claim, consider the source.

First, note that the FCC’s NPRM on changing the experimental licensing rules was published in the Federal Register on February 8. That means the comment deadlines are set. Comments are due March 10, and Reply Comments are due April 11. Consider filing comments in support of relaxed rules for industry as well as for academia. A few good comments have been filed already.  I point to the comments of Hans Schantz as exemplary.

On to the applications, which I list in order of frequency:

• BAE Systems Information and Electronic Systems Integration Inc. filed an application (with supporting exhibit) for special temporary authority to operate in Wayne, New Jersey on several frequency bands between 27 and 2003 MHz. This is to support development of a more cost-efficient and robust Ground Mobile Radio system for the Army.

• Raytheon Missile Systems filed an application (with supporting exhibit) for special temporary authority to conduct propagation tests in Tucson, Arizona on the following frequencies: 86, 87.5, 87.7, and 87.9 MHz (in the broadcast band). This is to aid in the development of transmission systems on those frequencies. (For a missile company, an unusual band in which to conduct experiments.)

• Michigan Technological University Aerospace Enterprise filed an application (with supporting exhibit) for experimental license to operate on 145.97, 435.52, and 2400.0-2483.5 MHz to support the Oculus-ASR satellite project. The frequencies are for downlink control at 1200 bps, uplink control at 1200 bps, and downlink image data at 230 kbps, respectively. “Oculus-ASR is a nanosatellite currently being developed to aid in the advancement of U.S. Space Situational Awareness as part of the University Nanosatellite Program. The program gives students the opportunity to work with industry sponsors in an effort to construct the best nanosatellite in a nationwide competition, hosted by the Air Force Research Laboratory (AFRL).”

• Carlson Wireless Technologies filed an application (with supporting exhibit) for special temporary authority to test a TV white space system using a TV broadcaster’s tower. The intent is to show how white space and broadcasting radios can coexist without objectionable interference. Operation is requested on 174-216 MHz (TV channels 7-13) in Oklahoma City, Oklahoma.

• Harris filed an application (with supporting exhibits) for special temporary authority to conduct field testing of software-defined radio (SDR) equipment in Melbourne, Florida on 232.375, 300.375, and 362.250 MHz. The testing will verify line-of-sight communication capabilities of radios ultimately deployed by the military abroad. This testing precedes more stressful at Army test ranges.

• BAE Systems Unmanned Aircraft Programs Inc. filed an application (with supporting exhibit) for experimental license to develop radio link equipment used in the unmanned aircraft systems operated by military branches for command, control, communications, computers, intelligence, surveillance, and reconnaissance  (C4ISR) applications. More specifically, the testing will involve the testing of a Microhard Systems model MHX320 wireless modem at BAE Systems’ factory in Tucson, Arizona. The MHX320 is a 310 to 390 MHz frequency hopping modem, which can be optimized for long distance communications of over 60 miles with throughput up to 230 kbps. Testing will be on 310.0-328.6 and 335.4-390.0 MHz.

• Raytheon Network Centric Systems filed an application (with supporting exhibit) for special temporary authority to test its Aurora and Wireless IP-capable Network (WIPN) radios, which provide a Mobile Adhoc Network (MANET) data network capability able to provide effective throughput up to 11 Mbps. Operation will be on 420-450 MHz in Fort Wayne, Indiana. This may be related to DARPA’s Mobile Ad-Hoc Interoperable Network GATEway (MAINGATE) program, which was initiated to develop systems required to enable network-centric warfare among Coalition and U.S. Forces, as well as to facilitate military operations with non-governmental organizations (NGOs) and first responders.

• Stark Aerospace filed an application (with supporting exhibits) for experimental license to test a remotely piloted aircraft for public safety and military applications.  Communications from ground to aircraft is by two uplink modes; a primary mode and a backup mode. The primary mode uses the bands 4500-4800 and 4940-4990 MHz. The backup uses the 465-510 MHz band. No information on the downlink is found.

• 4 Tech Media filed an application (with supporting exhibits) for experimental license to conduct white spaces experiments in Washington DC. This work is to be done jointly with District of Columbia government and the Community College of the District of Columbia, and is to investigate the usefulness of available white space spectrum for use in home networking applications.  The network is to consist of 5 base stations and 1,200 access points.  Although the request is for frequencies that span the entire UHF portion (470-698 MHz) of the white space band, only channels permitted for use by FCC rules are to be used. From the exhibits, it appears this experiment is supported by about $30 million of government grants, most by way of the American Recovery and Reinvestment Act.

• Motorola Solutions filed an application (with associated exhibit) for special temporary authority to operate in the 758-768 and 788-798 MHz bands to conduct tests in connection with the development of Long Term Evolution (LTE) broadband equipment. The testing will be conducted from up to three sites near the offices of Motorola Solutions in Schaumburg, Illinois. The requested frequencies encompass both the 758-763 and 788-793 MHz bands known as the upper 700 MHz D block, which has not yet been licensed for regular operation, and the 763-768 and 793-798 MHz public safety block licensed on a nationwide basis to the Public Safety Spectrum Trust.

• Florida Atlantic University filed an application (with supporting exhibits) for experimental license to operate on 824-849, 880-915, and 1850-1910 MHz in and around Boca Raton, Florida. The intent is to support lab exercises in the College of Engineering and Computer Science. Equipment to be used includes a GSM and a CDMA base station, operating at up to 100 watts effective radiated power. The University says it will coordinate with other licensees, which would include cellular and PCS operators.

• BAE Systems Information and Electronic Systems Integration Inc. filed an application (with supporting exhibit) for special temporary authority to conduct in-flight calibration and verification of a radio direction finding system on an unmanned aircraft at Victorville, California. Several frequency bands will be used between 880 MHz and 15.35 GHz. This test supports the company’s work for the US Air Force and DARPA.

• The University of California, Berkley, Computer Science Department filed an application for special temporary authority to operate in support of OpenBTS technology investigations. Testing would be on 890-915 and 935-960 MHz.

• DRS ICAS, LLC filed an application (with supporting exhibit) for special temporary authority to test Identification Friend or Foe (IFF) interrogator equipment that is being developed under a contract with the Italian Air Force. Operation will be on 1030 and 1090 MHz at Cheektowaga, New York.

• Lockheed-Martin filed an application (with supporting exhibits) for special temporary authority to test IFF systems part of a sale to the Royal Saudi Air Force. The system uses the TPS-77 transportable radar platform. Operation will be on 1030 MHz.

• Qualcomm filed an application (with supporting exhibit) for experimental license to operate on Cambridge, Massachusetts on 1915-1920 MHz.    Qualcomm is collaborating with faculty and students at MIT to further its testing, validation and application concepts around a peer-to-peer system currently under development. It appears to allow peer-to-peer communications over licensed spectrum without infrastructure support. Qualcomm says the primary objective is to explore creative application ideas which are enabled by this technology, validate system performance, and get feedback on the networking architecture from those studying the subject at MIT. There has been some press attention of this technology at this writing. For better information, a Qualcomm acquaintance has pointed me to this presentation and to this IEEE magazine article.

• Boeing filed an application (with supporting exhibits) for special temporary authority to operate on 2345?2390 MHz in air-to-ground mode at three locations in Delaware, New Jersey, and Texas.  No further details are publicly available due to a confidentiality request; flight test telemetry is a likely purpose. The Navy is not enthusiastic about the proposal, and the application has yet to be granted.

• Sportvision filed an application (with supporting exhibit) for special temporary authority to operate an auto race track wireless data system that would allow television viewers to see, displayed on-screen, the real-time location of cars during a racing event. Vehicles equipped with GPS receivers and radios would provide updates every 200 milliseconds. Operation will be on 2395-2400 MHz at 23 motor speedways across the US. Modified Wi-Fi hardware will be used. The requested frequency band is just below the 2 GHz ISM band (high noise levels preclude operation there) and is allocated to the Amateur Radio Service. No interference is expected due to the short duration of operation and low power involved (1 watt). Operation will be coordinated with the ARRL.

• Florida International University filed an application (with supporting exhibits) for experimental license to operate a WiMAX base station on 2590 MHz in Miami, Florida in support of the Global Environment for Network Innovations (GENI) project.

• 4-D Security Solutions filed an application (with supporting exhibit) for experimental license to test surveillance radar on 8.75-8.95 and 10.32-10.48 GHz at locations in New Jersey and Wisconsin. The radars to be tested are Elta Systems models EL/M-2105 and EL/M-2129. This testing is in support of the company’s development of homeland security systems intended to provide protection for sensitive installations, borders, and coastlines.

• Denso Corporation filed an application (with supporting exhibits) for experimental license to operate nationwide on 24.125 and 25.5 GHz. Due to a confidentiality request, details of the experimental plan are not publicly available. This experiment is likely related to Denso’s ongoing work developing vehicle radar systems to detect preceding vehicles and obstacles as input to anti-crash and pre-crash systems.

• Battelle filed an application (with supporting exhibit) for special temporary authority to operate an experimental point-to-point communications link operating at millimeter-wave frequencies. The link uses optical components to generate and modulate the signals, and has the capability of transmitting 10 Gbps on a 100 GHz carrier. Operation will be at three locations on 95-105 GHz. The proposed study includes investigation of candidate modulation formats at distances up to 1 km.

• ShawnTech Communications filed an experimental application about which nothing is known due to a request for confidentiality. ShawnTech provides phone and related services to the corrections industry. This may be an experiment of cell phone jamming or managed access technology to address contraband wireless devices.

The ITU now says that while it still considers IMT-Advanced as 4G, it’s not the only 4G, since that term is used to describe other high-performing radio systems such as LTE and the previous version of WiMAX.

Here’s how the ITU put it:

As the most advanced technologies currently defined for global wireless mobile broadband communications, IMT-Advanced is considered as “4G”, although it is recognized that this term, while undefined, may also be applied to the forerunners of these technologies, LTE and WiMAX, and to other evolved 3G technologies providing a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed.

This is a victory for IEEE 802 which had sought a broadening of the definition for just the reasons the ITU states.