(Originally posted at http://www.von.com/blogs/guest/2009/01/a-cell-for-all-reasons.aspx )
Fortunately, service providers and technology vendors understand the principles previously described. Typically, a network is deployed for coverage in the first instance, by using large (macro) cells. These tend to be mounted on towers with high transmit power and highly sensitive antenna arrays to hear the low powered “whisperers” at the edge of coverage. Of note, however, is that while published 3G data rates (HSDPA) may claim to be in the 1.8mbps to 14.4mbps range, the “real” capacity throughout the cell of a 3G macro-cell base station is around 10mbps, meaning that there’s 10mbps to share across all of the users in the coverage area. Even the much vaunted 4G, with the first release of LTE offering data rates of over 320mbps for downlink and over 170mbps for uplink, has an estimated capacity per macro-cell of ~45mbps. This means that the performance averaged across all users will not (cannot) approach the types of speeds being talked about loosely in the press.
As user density increases, it becomes necessary to add capacity to the system. This is done by sub-dividing macro cells into smaller micro and picocells. Average data rates increase, as more users are able to transmit and receive at higher modulation rates (because they’re closer to the “bullseye”). System capacity increases as a multiple of the [number of cells per cell capacity]. What this means is that it is possible to deliver far greater capacities over a comparable area (greater than 1gbps per square mile!) by shifting to a micro-cell-based network design. But what it also means is that there is a need to have a backhaul strategy that supports both this level of capacity and that which is implementable in the physical location of the micro-cell nodes.
At the complete other end of the spectrum is the emergence of the femtocell. Think of this as a combination of a Linksys style gateway/router with an HSxPA, WiMAX or LTE access radio. The rationale behind this is to extend 5-bar performance indoor, to users in their homes or offices. End users will connect this to their existing cable or DSL connections and be able to use their LTE devices indoor, much as they do with Wi-Fi today. Whether customers feel a need to deploy cellular femtocells when they already have Wi-Fi deployed is an open question and one deserving of consideration.
That’s my .02!
Martin Suter is vice president of business development at BelAir Networks, a provider of broadband mesh solutions for Wi-Fi, WiMAX, 4.9 GHz Public Safety and 5.9 GHz ITS networks. Previously, Martin was the CEO at Cohda Wireless, where he raised the company’s profile and negotiated a licensing deal with a Fortune 100 vendor in its core franchise. Prior to Cohda, he was vice president of business development at MeshNetworks Inc., a classic tech transfer/disruptive technology success story that achieved a major liquidity event for its investors in Q4/2004 with its acquisition by Motorola. Martin also was responsible for building several high profile alliances with and for leading technology companies, including Fujitsu, Microsoft, Netscape, Sun Microsystems, and Teradata. Additionally, Martin has successfully negotiated technology transfer, distribution and/or licensing deals with companies like 3Com, BioChem Pharma, Dow Chemical, Exodus, Fujitsu, IBM, Microsoft, Motorola, Netscape and Sun.