Outdoor WiFi instead of cellular for campgrounds

The vacation grounds of upstate New York, particularly the Adirondack area suffer from poor cellular service. Recent fatal accidents have left the public blaming the lack of cell phone coverage for slow emergency response. There are a few things professional users (including volunteer emergency services) and prosumers can do to improve in-car cellular service. However, with the AMPS shutdown, we’ve lost the least common denominator roaming between networks, which is also making coverage in remote areas worse.

Readily available technology yields:

  • $500 3-watt cell phone automotive/RV/SOHO bidirectional amplifiers (direct or wireless coupling to handset) greatly improve coverage over the internal antenna cell phone
  • $500 900 MHz long-range cordless phone covers large home / country estate and higher-power units cover campgrounds and remote worksites
  • $500 worth of outdoor WiFi APs will blanket several acres of worksite/campground with 802.11 2.4 GHz WiFi for modern phones and laptops.

Cellular repeaters/amplifiers

There isn’t any fundamental difference in radio waves between two-way radio and cellular. The ubiquitous handheld cell phones with internal antennas suffer several dB disadvantage vs. older handheld phones with external antennas. Add several more dB penalty for handheld cell phone used in car or building. Cellular coverage can be significantly augmented by using bidirectional amplifiers in the home, office or vehicle. However, terrain in mountainous areas precludes 100 % coverage of areas such as the mountains of upstate New York.

Automotive

Automobile-installed cellular phone repeaters and amplifiers can yield up to 3 Watts output power from your car back to the tower, just like traditional bag phones. The bidirectional amplifier costs about $200-$300, the phone adapter another $20, and the install probably $100-$200. This could be a life-saver or at least a time-saver in remote areas. The cellular signal is attenuated by more than 10 dB in both directions with a handheld phone in the car compared to an external antenna. However, in mountainous terrain, oftentimes the problem is simply terrain blockage, so sometimes no amount of hardware will help. This is where emergency services use their own VHF/UHF repeater towers to fill the cellular gaps via radio.

Campsite/remote worksite

Burning Man 2007 saw the debut of standalone cellular service via USRP. This is in my opinion the only feasible way to cover remote worksites and campgrounds with cellular, when the provider’s network doesn’t yield coverage. Of course an elaborate bidirectional outdoor system is possible but to my knowledge not COTS–let’s examine.

Bidirectional amplifiers can have 20-80 dB of gain depending on the model. The lower gain (< 40 dB) models assume the phone is within about 10 meters of the amplifier–and that with a good signal at the donor amplifier. If the phone already does not have an adequate signal, then a high-gain donor antenna placed up high is required. To cover outdoor areas with bidirectional amplifier, free-space loss and antenna pattern analysis shows that the isolation distance required is large enough to require fiber optic interconnection to be practical. This translates to significant expense, probably excessive for a large number of campgrounds and remote outdoor worksites.

Solution

A good solution for providing telephone and data coverage to campsites and remote outdoor worksites consists of two-way radio with interconnect along with outdoor WiFi APs.

The Ubiquiti Nanostation 2 at < $100 provides 802.11g in the 2.4 GHz band compatible with Blackberry Curve, Apple iPhone, and other popular modern cell phones. The directional antenna extends coverage to well over 100 meters outside when placed at 5-10 meter height. In a very simple scenario, Nanostation 5’s could be used on on-site backhaul for the Nanostation 2’s. Increasingly, people are interested in text-based communication and Skype than low-quality cellular voice. Campers and workers respectively may be more interested in following the news or downloading datasheets.

For emergency purposes, verify with local and state regulations the following suitability. Two-way radio callboxes are available for < $500, and if your campsite/remote worksite has only one security guard on duty at night on patrol, their walkie-talkie can communicate with the callbox and on the same (or different) channel dial the telephone for half-duplex communications with emergency services over the radio channel. A callbox per bloc of cabins or periodically throughout the worksite may suffice.

For long-range staff cordless telephones, EnGenius is a company making phones with external antenna base stations capable of kilometer range. For extremely large outdoor areas, EnGenius Pro models connect to PBX for multiple base stations and many dozens of handsets. Even with prosumer 900 MHz cordless phones, it is possible to get over 100 meter range from the base station when it’s placed in a high, clear view location.

Reference

Bidirectional amplifier white paper

Categories:

Updated:

Leave a Comment