Look, Ma, No Towers

If you have infinite resources to get a job done, then you can do it any old way," said Gary Howard, WirelessNorth director of engineering and technical operations. "But if you need to be efficient, then it's a matter of balancing decibels and dollars."

That's why Howard selected PCS-over-cable technology in favor of a more traditional build.

When Howard came to WirelessNorth a year ago, he inherited a build-out in Duluth, MN, that was behind schedule. A few sites had been constructed, but speed was an issue. So Howard got out his propagation-analysis tool (Decibel Planner) and went to work.

"I calculated the probability at any given location, if someone has a phone next to them, that it will actually ring if someone calls," Howard said. In Duluth, he looked at the core area where most of the people lived and worked, and found that it would require 28 sites for coverage if he built the cellular-style, standalone sites. Although Howard needed the coverage, he did not need the capacity of 28 sites, and he found the cost excessive.

"The question was how can we do it with fewer base stations -- not having a 1-to-1 ratio with a base station at every site -- and distribute RF from the base station throughout the neighborhood without building a big tower in the middle of the neighborhood," Howard said. He looked at several options and concluded a distributed-antenna system, PCS over cable, would make sense for Duluth and its adjacent city, Superior, WI.

With PCS over cable, equipment installed on the cable strands and at the cable plant head-end provides for the reception, backhaul and transmission of PCS signals between handsets and BTSs.

COX INSTALLATIONPCS over cable is a technology that goes back to the "old days" of PCS -- meaning the mid-1990s. The technology helped Cox Communications get a pioneer's preference license for the PCS system in San Diego, which subsequently won a technology award from PCIA. As part of the Sprint PCS network, that system consistently ranks well in the J. D. Power and Associates customer-satisfaction surveys.

But although PCS over cable made a strong start, it languished at the starting gate for a few years.

Now that may be changing.

"I will tell you that this technology works great," said Rick Rappe, Wireless North CEO, who plans further use of the technology as he builds out his system.

"It allows us with fewer base sites to broadcast from many more sites and fill in coverage holes that would have been impossible with a traditional build," Rappe said.

When the decision was made for PCS over cable, WirelessNorth had the PCS licenses, but it lacked another essential element -- cable. In Duluth and Superior, the cable operator is Bresnan Communications.

Lenny Higgins, Bresnan senior vice president, telephone and data services, said the two companies had worked together before, which made it easier to do so again. Matchmaker in this instance was Sanders, a division of Lockheed Martin, which had developed the PCS-over-cable technology for Lucent to install in the Cox system. (In June, Lockheed Martin announced the sale of the Sanders' Telecommunications Systems business -- which includes PCS over cable and related technologies -- to Transcept, a newly formed affiliate of Spencer, Trask & Company. Lockheed Martin will remain one of the owners.)

WirelessNorth benefited from the fact that Bresnan had rebuilt its system using hybrid fiber coax, so it had the 2-way capability and capacity to accommodate the PCS carrier.

Bresnan had upgraded its network on speculation that there were new services out there that would provide a return on its investment, Higgins said. The revenue it has received from its contract with WirelessNorth has allowed it to expand its network to areas it could not serve before.

PARADIGM SHIFTThe idea of moving from an island of coverage with a tower to a network of coverage with distributed antennas is one that comes with a learning curve, according to Steve Johnson, Transcept president and former Sanders director of telecommunications systems.

"This is a reasonably new concept and not within the general paradigm of the way the wireless industry has built out," Johnson said. "But I believe we have a lot of evidence of the advantages of doing this the way we are doing this, not the least of which is that it saves the operator considerable money." He calculates a 30% to 50% savings using PCS over cable compared with using traditional towers.

Neither Howard nor Rappe could quantify the cost savings for WirelessNorth, though they did agree there was a savings. Rappe said the technology was giving them a much better footprint than any type of traditional build.

Howard builds with both a head-end architecture and a hub architecture. In the former, several BTSs and the Trancept interface converter are located in the cable head-end and distribute out from there with all antennas taken off the cable media.

With the hub architecture, Howard has a single base station at a site, and from there the signal is distributed through cable or fiber spokes. This works especially well for a campus or a big office building. Howard said carriers can offer 4-digit dialing within the building with one base station and charge one rate. When customers leave the building or campus, they use different base stations and are charged at a different rate.

He also said a distributed-antenna system is advantageous in delivering data because it gets the RF closer to the customer.

PRODUCT ENHANCEMENTSPCS over cable has evolved since it first was installed in San Diego. This includes improving its use of the cable plant by setting the control and reference tone within the CDMA signal itself, which uses less bandwidth in the cable plant, Transcept's Johnson said.

"We've come out with a robust OAM&P (operations, administration, maintenance & provisioning) solution for the network that is now a mainstay of our (version 1.9) product line and will be of our other products as well," Johnson said.

He also cited the product's flexibility. Reconfiguring your network is fast and easy when you only have to move your cable microcell integrators (the boxes that hang on the cable), not your towers. You can install each of these transceivers in less than two hours and in a variety of ways, he said. WirelessNorth has put them on rooftops, above suspended ceilings in buildings and even on the top of a tower. Because there is no land acquisition or permitting, and fewer or no zoning restrictions, the process goes more quickly.

The zoning issues alone can make it a solution worth considering. Johnson believes that the C-, D- and F-block carriers are going to have problems with tower siting since the A- and B-block carriers have preceded them, and some communities, organizations and politicians are getting strident in their opposition to towers.

In a Feb. 25, 1999, speech, Lost Opportunities in the Telecommunications Act of 1996, Sen. Patrick Leahy (D-VT) said, "Mobile phone service using PCS over cable only requires small whip antennas. You do not have to build huge towers with flashing lights near people's houses."

Yet Transcept stops short of aligning itself with any of the groups opposing towers.

RELATIONSHIP BUILDINGOne of the more challenging aspects of the WirelessNorth build-out was forging the relationship with Bresnan. When PCS was installed in San Diego, Sprint and Cox both had ownership interests, so the issues were different.

WirelessNorth and Bresnan had to work out an arrangement with no precedents to guide them.

Johnson said Transcept has modeling techniques it can supply to each side in order to let them work out the best arrangement. For example, there are benchmarks where they might start to negotiate.

But what happens if the cable carrier finds a better use for its bandwidth in a year or two? Is the PCS carrier out of luck? This could be an issue with WirelessNorth and Bresnan as the latter currently is considering offers to purchase it, according to cable-industry trade publications.

WirelessNorth's Howard isn't worried. He notes that any shared-bandwidth system can serve a PCS carrier. The contract he negotiated with Bresnan calls for a year's notice if Bresnan wants to walk away from the arrangement. WirelessNorth would have time to find an alternative.

"Look at all the CLECs out there who have agreements with the city and can pull cable," Howard said. "There are cable companies getting into wireless, power companies getting into cable and wireless." He suggests investigating all options before getting on anyone else's bandwidth and having a close relationship with the company whose bandwidth is being shared. In fact, a wireless carrier may want to look into pulling its own cable or fiber.

"Even if it costs $10,000 per mile, you're still way ahead," Howard said.

SPRINT SKEPTICALAlthough the distributed-antenna system is working well for WirelessNorth, Sprint PCS views the technology with more restraint. Its experience with Cox in San Diego has not made it eager to use the PCS-over-cable technology elsewhere in its system.

"The cost structures, the economics of doing it don't really add up," said Tom Murphy, Sprint spokesperson.

He said Sprint has looked at the technology in other markets and continues to look at it, particularly in instances of hole filling, but the company won't make a major investment in it.

"We have close to 11,000 cell sites nationwide," Murphy said. "Good old antennas mounted on rooftops -- (it) works great."

Lucent, which installed the Sanders technology in the Cox/Sprint system, believes customers have cooled on the PCS-over-cable concept, according to Lucent spokesman Sam Gronner.

"The cable companies refocused on other lines of business such as Internet access," he said. "(PCS over cable) is viable, and it is working, but it was quite a working curve for us."

"People don't understand it; that's the problem," said Dave Shultz, a partner along with Craig Stanziano in Cable Distributed Wireless Group. Stanziano helped design Cox's PCS-over-cable system, and Shultz came in as a Lucent contractor to do optimization and manage the system. Now they're eager for the product to take off and ready to work with wireless companies that want to use it.

"It offers tremendous freedom to a designer," Shultz said. In fact, he believes the cellular market needs an 800MHz product.

"(Cellular carriers) have areas they have been unable to cover for years, while the PCS companies are still scrambling to cover their initial areas," he said.

Johnson said an 800MHz product is possible, although an IS-136 product probably is next. His current product line includes PCS over cable for CDMA and GSM, PCS over fiber and PCS over microwave.

WirelessNorth's Howard knows there is interest in the technology judging by the 40 to 60 calls he has received in the past few months from those who wonder if a distributed-antenna system might work for them. First he advises:

* Look at the terrain and population you are trying to cover, plot it out on a tool, and analyze it from a propagation and capacity perspective.

* Check out the political relationships in your locale concerning towers and sites.

Once it looks like there's clearly an up side for using a distributed method, he tells other carriers:

* The biggest issue to think about is the bandwidth. Who is going to be pulling or be responsible for the cable or fiber doing the distribution?

* It is essential to get sites, but it is not too difficult to walk up to someone and say you'll give him $100 a month to place something the size of a breadbox and an antenna on the roof where it won't even be seen.

* The types of antennas you use are important. WirelessNorth uses omnis, parabolics and panel-mounts. Its standard sectorized antenna is from EMS, a 65-degree antenna with 4 degrees of electrical downtilt.

* Even if you have your own designer take care of the design, you still should have him work with someone who has done it before. The biggest mistake people have made is to treat this like a traditional build.

PCS carriers that avoid doing their homework and are sloppy with their RF planning probably won't select a PCS-over-cable solution, Howard said.

"I bet I could go to every PCS installation that's ever been done and say a third could have been built more efficiently using a distributed-antenna system," he said.

When a WirelessNorth customer in Duluth, MN, places a call with his CDMA handset, the CDMA signal is received by a nearby cable microcell integrator (CMI). The CMI converts the signal to a pre-assigned transport frequency for the cable TV (CATV) reverse path. The signal travels over the CATV network on the allocated reverse-path spectrum to the cable plant head-end. At the head-end, Transcept's head-end interface converter (HIC) receives the PCS signal on the CATV carrier frequency, converts the PCS signal back to the original PCS frequency and sends the resulting signal to the BTS.

The forward-path operation is similar to the reverse path. The BTS generates the CDMA signal at PCS frequencies and passes this low-power RF signal to a HIC module at the cable plant head-end. The HIC converts the signal to an intermediate frequency compatible with the cable-plant forward-path channel assignment. The signal then is transported over the hybrid fiber coaxial network to the CMI. Within the CMI, the signal is converted back to the PCS carrier frequency, amplified and transmitted for reception by the CDMA handset.

Typically, 6MHz is the downstream and 4MHz is the upstream path required.

The head-end control unit (HECU), also located in the cable system head-end, functions as the operations, administration, maintenance and provisioning control processor, monitoring CMI/HIC parameters, processing detected errors, generating alarms and displaying network information. All HECU messages to and from the CMIs are directed through the controlling HIC. One HECU provides control and status for up to 26 HICs and more than 900 CMIs.

PCS over cable can be used as an addition to a macrocellular network in order to fill holes and extend coverage.

For example, an operator may wish to increase BTS usage by extending the coverage to an adjacent area that does not have line-of-sight to the macrocell. In this case, PCS over cable can simulcast the same frequency as the macro-cellular sector without impairing the sector's performance, according to Transcept. An operator can implement the system using either dedicated coax cable overlashed along an existing right of way or existing cable plant passing through the affected area.

PCS operators with completed macrocellular build-outs also can create a microcellular underlay with Transcept's cable microcell integrators. This underlay can offload the macrocells and provide improved in-building coverage, wireless local loop and other services as well.