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Mobile Cell Phone Towers For Disaster Relief

Posted by timothy on from the well-seattle's-a-reception-disaster dept.

cerberus4696 writes "According to today's Denver Post, Verizon recently premiered one of its new Cells On Light Trucks (COLTs), a complete, self-contained CDMA cell that can be moved to wherever it's needed, such as the scene of a natural disaster or a large public event. Since a standard CDMA cell can only handle a theoretical maximum of 62 calls at a time (usually less in practice), the network of permanent fixtures can quickly become overloaded in high-use situations. Verizon already uses a larger version of the system known as a Cell On Wheels (or COW; gotta love these acronyms), but as it takes three trucks and the better part of a day to deploy, nimbleness of response has apparently been an issue."

2 of 210 comments (clear)

  1. Which is why Ham ops are still useful by MooseByte · · Score: 4, Informative


    Which is a good reason that Ham radio ops are still useful, particularly in disaster relief scenarios where much of the local infrastructure may have been destroyed.

    But first you have to get us to stop talking about the weather and our rigs. :-)

  2. Re:wow, only 62 calls at once? by Phil+Karn · · Score: 5, Informative
    That figure is a little misleading. 61 (not 62) is the number of available traffic channels per sector and per RF channel for the original mid-1990's IS-95 CDMA standard. The number 61 comes from having 64 Walsh code channels, minus three for overhead: pilot, sync and paging.

    Sectorization refers to the practice, common with all cellular technologies, of dividing up the area around a cell site into regions, or sectors, each served by its own set of directional antennas. Three sector cells are extremely common; that's why so many towers have triangular platforms with a set of antennas on each side. There are usually three antennas on each side: one for transmit and two for receive, with the extra receive antenna providing spatial diversity.

    Most CDMA cell sites in built-up areas have three (or six) sectors, operate on more than one 1.25 MHz RF channel, and use the newer CDMA 2000 1x standard. That can easily provide a total cell capacity of considerably more than 61 calls.

    CDMA 2000 1x doubles the number of Walsh code channels (to 128) by adding a second set of traffic channels in quadrature to the original 64. Virtually all CDMA phones sold over the past few years do 1x.

    Because of CDMA's inherent robustness, the same RF channel can be reused in adjacent cells and even adjacent sectors, greatly increasing the overall capacity of the spectrum in a given area. Because no careful frequency reuse plan is required, CDMA is also very well suited to the rapid deployment of cells in "hot spots" as described in this article.

    Disclaimer: I work for Qualcomm.