Making the case for wireless backhaul for small cells

Wireless vendors are rolling out their small cell architectures, predicting that operators will soon have to augment their macro networks with pico and micro deployments to fill in the capacity needs for ever-hungry mobile data services. And as all of those small cells will require high-bandwidth connections to the network core, there may be a huge potential market for backhaul vendors. One vendor in particular, BridgeWave Communications, believes that small cells could become the point of entry for wireless backhaul in the U.S., where operators have traditional shunned point-to-point radio connections in favor of wireline technologies.

Last week, BridgeWave announced a new family of millimeter wave compact radios, called PicoHaul, targeted specifically at the high-capacity, tiny-footprint small cell. According to BridgeWave CEO Amir Makleff, one Tier I 4G operator—by which he means either an LTE or WiMax operator—in the U.S. has already conducted a single-cell trial with its first PicoHaul radio, the PG60C, and is now weighing a commercial launch. While an operator trial in and of itself is nothing significant, the context of the trial is, Makleff said. The operator is exploring the use of small cells to add capacity to the network, rather than just use them as a one-off means to extend coverage, and that the operator is looking for alternate means of providing backhaul links to that small cell underlay, Makleff said.

While fiber-to-the-cell site is quickly becoming a reality, a full-scale small cell underlay would move the network from the tops of towers to light poles and building walls, where fiber isn’t yet present and would cost enormous sums to build to such scale, Makleff said. “We’re talking about 5,000 to 10,000 base stations installed on light poles in a single city,” Makleff said. “You can’t do that with fiber.”

A small-form radio—the PG60C is the size of 4-inch pipe—however, could be used to link small cell sites back to cell towers where traffic could then piggyback on the fiber links serving the macro network. That’s essentially to the gist of BridgeWave’s operator trials, Makleff said. The operator evaluated whether the PicoHaul product could maintain a 1 Gb/s connection over 60 GHz frequencies at a kilometer’s distance, even testing whether the signal degraded as light-poles swayed in the wind, Makleff said.

Small cells have been a hot topic for vendors lately, all of whom have launched some sort of small cell product, though under all sorts of different names. Alcatel-Lucent (NYSE:ALU) calls them metro cells (CP: The incredibly shrinking network), while Huawei is focused on what it calls microcells (CP: Huawei doing small cells the old-fashioned way). Ericsson (NASDAQ:ERIC) and other vendors are building integrated antennas and radios, shrinking down the equipment footprint to fit into ever-tighter recesses (CP: Ericsson introducing new compact radio head). Meanwhile, Nokia Siemens Networks (NYSE:NOK, NYSE: SI) have both announced new modular radio access network (RAN) architectures they claim will be the basis of new network topologies (CP: NSN pours out Liquid Radio). ALU’s lightRadio Cube reduces the radio unit down to the size of Rubik’s Cube, which can then be stacked to form different-sized cells (CP: ALU’s new building-block architecture does away with the base station).

All of these products fall under the concept of heterogeneous networks, in which a new network built underneath the macro-umbrella becomes the new means for adding capacity to the network. While the macro network continues to function as the primary coverage network, dense clusters of small cells provide its primary capacity in congested urban areas. To meet the backhaul needs for those deployments backhaul suppliers have started coming out with compact products. In addition to BridgeWave, vendors like Aviat (NASDAQ:AVNW) and Exalt Communications have designed point-to-point wireless links for small cells. Taqua is using core WiMax technology to build backhaul distribution nodes for small cells (CP: Taqua reinvents itself with new take on backhaul).

Other vendors are promoting using other access technologies to link small cells such as FTTx, in the case of Zhone Technologies, and the cable plant in the case of BelAir Networks (CP: BelAir hanging picocells off of the cable plant). All of the major vendors also have been redesigning their own microwave and Ethernet backhaul products for small deployments.

More: Will operators embrace wireless backhaul?