This is the first in a series of commentaries that will address issues facing the Public Safety and First Responder communities. It is a free service offered by Andrew M. Seybold, long considered an advocate for public safety communications. To receive the PUBLIC SAFETY ADVOCATE, visit www.andrewseybold.com and sign up for it online. You can also sign up for his TELL IT LIKE IT IS blog post notices and his COMMENTARY e-newsletter, also free to subscribers.
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Over the years, Andrew Seybold has spoken out about many issues that affect the daily lives of our first responders, most notably the current struggle between Public Safety and the FCC over the Public Safety 700-MHz broadband network and the inclusion of the D Block of spectrum into that system. Sign up today as this issue and others are discussed and add your own views by commenting on the articles directly on the website.
Comments on FCC White Paper on Capacity
Entitled “The Public Safety Nationwide Interoperable Broadband Network: A New Model for Capacity, Performance and Cost”
In June 2010, the FCC published its second white paper supporting its recommendations in the National Broadband Plan (NBP) submitted to Congress in March of this year. The first white paper detailed the FCC’s ideas related to the cost of building and operating a nationwide public safety Broadband network. I reviewed that document and prepared my own white paper challenging many of the FCC’s assumptions and questioning its findings.
This second white paper details the FCC’s analysis of the capacity of the 10 MHz of spectrum already assigned to the public safety community and claim that 10 MHz of broadband spectrum (5 MHz by 5 MHz) will be sufficient for most public safety broadband requirements well into the future. The following is my response to the FCC’s second report.
In the introduction to the Capacity Paper, one of the authors recaps points made in more detail in the body of the paper:
“The Federal Communications Commission (“FCC”) has performed a technical analysis of the capacity and performance of the public safety broadband network assuming that the National Broadband Plan recommendations concerning this network are implemented. This analysis includes examining different emergency situations based on actual experiences and as submitted in the record of the National Broadband Plan. This analysis shows:
- The 10 megahertz of dedicated spectrum allocated to public safety in the 700 MHz band for broadband communications provides more than the required capacity for day-to-day communications and for each of the serious emergency scenarios set forth below.
- For the worst emergencies for which public safety must prepare, even access to another 10 megahertz of spectrum would be insufficient. Accordingly, priority access and roaming on the 700 MHz commercial networks is critical to providing adequate capacity in these extreme situations. Moreover, priority roaming is a cost-effective way to improve the resilience of public safety communications, along with its capacity, in a way that a single network cannot provide.
- The capacity and efficiency of a public safety broadband network will far exceed the expectations of someone who has only experienced narrowband land mobile radio (LMR). This is because of the system architecture, density of cell sites, density of cell sectors per site, network and spectrum management, and the use of new and emerging technologies.
- Public safety can make more capacity available when and where it is needed by using all of its spectrum resources appropriately and effectively, no matter how much spectrum is available (e.g., use the 700 MHz band for mobile devices and other frequency bands for fixed devices).”
In reviewing the assumptions the FCC used in reaching these conclusions, I take issue with the following:
- The FCC is trying to equate voice with data traffic information. Voice communications requires far less spectrum per conversation than broadband data services require. Further, the types of data have a huge impact on the amount of bandwidth available and the capacity of the network within a given cell sector.
- The FCC claims that video data rates of 256 Kbps will provide sufficient video resolution for most public safety video applications. I and many others disagree with this assumption for many of the video feeds that will be employed by public safety.
- The FCC claims that land mobile radio systems (LMR) are underutilized most of the time. This is not a correct assumption. LMR systems, as used by public safety, do have periods of light usage, but there are many times every week when these systems are supporting voice traffic that is beyond the capacity of both the existing LMR systems and the capabilities of the dispatch centers to keep up with the demand.
- The FCC believes that roaming onto commercial networks will occur on a sporadic basis. My research shows that having only 10 MHz of spectrum available will result in having to roam on commercial networks in at least the top 100 metropolitan areas on a daily basis, and for long periods of time for each occurrence.
- The FCC assumes that the public safety community will have access to 60 MHz of broadband spectrum (its own and that operated by commercial networks). This assumption is not based on any current rules that mandate commercial priority roaming or type of priority roaming and assumes that the winner of the D Block at auction will make its spectrum available for use by the public safety entities, yet its current recommended rules for the D Block auction do not require such cooperation between the public and private sector.
- The FCC based its usage models only on major scenarios spread out over large geographic areas of a city or jurisdiction. There are no assumptions that look at capacity requirements for smaller incidents that occur on a daily basis and are fairly local in nature and, therefore, will have broadband coverage from only one or perhaps two cell sectors.
- The FCC believes that local ordinances need to be changed to require the installation of inbuilding network cells (femto, pico, or distributed antenna systems). Yet the FCC has no authority to require that local communities actually do update their existing ordinances, nor does it take into account the cost of providing this inbuilding coverage, nor how it is to be integrated into the network.
- The FCC’s discussion of how much spectrum is already available to the public safety community is flawed in a number of ways. It counts the broadband spectrum at 4.9 GHz that provides only local-area coverage and does not penetrate buildings, it includes the 220 MHz band that is presently used in only one area of the United States because of a conflict on the Canadian border, and it does not take into account that existing channelized spectrum cannot be aggregated into spectrum that could be used for broadband because the channels already allocated to public safety are interleaved with channels assigned for other land mobile radio services.
- The FCC claims that the public safety community’s only rationale for requesting that the D Block be reallocated to public safety is so it can build fewer cell sites and therefore a less expensive network. This assumption is wrong, since public safety is planning to make use of the same number of cell sites recommended by the FCC (44,000 nationwide). The additional spectrum being requested is to provide additional capacity for the network.
- The FCC used the New York City report on bandwidth requirements to support its own position. However, instead of using all of the assumptions provided in that report, it chose to discount the requirements listed for video services and use its own assumptions as to the number of video feeds that would be required and the bandwidth consumption of each connection.
- The FCC assumes for the purpose of this paper and in its general findings, that a guard band is not needed between the D Block and the public safety spectrum. However, on May 18, 2010, the FCC requested comments from interested parties to provide input on whether or not a guard band will be needed, even though the assumptions in its white paper are based on a guard band NOT being necessary.
- The 700 MHz commercial spectrum that was already auctioned and on which networks are in the process of being built did not carry any requirements for priority access for the public safety community. It is unclear to me whether the FCC has the authority to now require these network operators to provide some type of priority roaming with the public safety community.
It is clear that those involved in preparing the FCC white paper on capacity tried to make the results fit the recommendations they already included in their National Broadband Report to Congress. In reality, this capacity study should have been prepared and released prior to their recommendations to Congress. The FCC focused only on major events or incidents and did not run scenarios based on day-to-day operational requirements. These daily incidents will occur in small geographic areas, sometimes within only a one or two block area of a city or within one-quarter or one-half mile of a jurisdiction. In many cases, these areas will only have broadband coverage from one or two cell sectors. Since this is the norm for public safety responses, this should have been the criterion for evaluation of the amount of spectrum required.
The FCC statement that capacity is based on a number of cell sectors per site, times the amount of spectrum available within each sector, divided by the frequency reuse factor, is true and correct. However, its assumption that public safety would build out fewer sites if it had more spectrum available is not correct. In the case of public safety and its planned network, doubling the amount of spectrum it has available will double or more the amount of bandwidth available within each cell sector. Therefore, the assumption that total capacity is based on other factors as well is not correct. The proper calculations should look at a single cell sector, map the bandwidth available within that cell sector, and then calculate the amount of data traffic (data and video) that will be required both inbound and outbound for typical incidents including a building fire, bank robbery, hostage situation, gang fight, and other incidents that occur on a daily basis but in random locations within jurisdictions.
Further, their discussion of cell sectors and capacity assumes that incidents will occur in areas already heavily covered by commercial network operators. This too is a flawed assumption. If we look at New York City as an example, the commercial operators have learned from experience that in the Theatre District, when the shows let out, the demand for voice and data services will peak. The network operators design and build their systems based on this type of demand, primarily in identifiable locations. The reality of the situation is that criminal events, fires, and other emergencies are not predictable by location, and in many instances the demand for public safety services will occur in areas of the jurisdiction that are lightly served by commercial operators, but bandwidth must be available for public safety.
It is my opinion that the authors of the paper were charged with reinforcing the position previously taken by the FCC that the D Block should be auctioned to a commercial operator. Instead, they should have been charged with taking an uncommitted view of the needs of the public safety community and developing a paper based on an understanding of the differences between commercial and public safety networks and requirements. It appears that this FCC white paper was developed for the purpose of further justifying a position it already recommended to Congress in the National Broadband Report. There are many discrepancies in the FCC white paper and a number of assumptions that, while they may be valid for commercial networks, are not valid for a mission-critical public safety broadband network.
The bottom line for me is that the FCC delivered a report that attempts to once again justify its position that 10 MHz of spectrum is sufficient for use by public safety on a daily basis and that during the occasional times when this is not enough, public safety will be able to make use of commercial network operators’ spectrum on some as yet undefined type of priority access. Further, the studies referenced in this report look at broadband capacity from a macro level rather than from a cell sector level. The result is a paper that does not address the real-world broadband requirements of the public safety community on a daily basis, though it does meet the FCC’s goal of justifying its recommendations already presented to Congress.
Andrew M. Seybold
Note: My full response to the FCC’s capacity white paper is below in PDF format.