Fixing the Cellular Network: Backhaul is the Key

I've lately been contacted by the reps of a number of firms that sell high-capacity point-to-point wireless systems designed for use in carrier networks as backhaul links. If you're not familiar with the term in this context, backhaul is the connection between infrastructure nodes, most commonly cell sites, and the rest of the network, like a mobile switching center or similar elements. As is the case in enterprise networks, T1 and E1 connections have dominated this space for many years, because (a) they were easy, if not cheap, to get from wireline carriers, and (b) they are well-suited to telephony because they are telephony. But 1.544 and 2.048 Mbps no longer seem interesting or fast, because they're not. In fact, for the cellular industry to continue to grow and even simply compete, these links need to be replaced - and soon - with more contemporary broadband connections.

The reason for this is simple - the voice market is saturating in most industrialized countries, and growth in data services is the future for both the carriers and their customers alike. And yet the carriers are forced into a posture of scarcity at least in part because they lack the backhaul capacity necessary to offer the megabits of service to their individual data users that are becoming feasible with EV-DO Rev A, WiMAX, HSPA, and LTE. By the way, it gets worse - the ITU's IMT-Advanced project, for example, is considering throughput of 100 Mbps to as high as, believe it or not, 1 Gbps. The IEEE's 802.16m (A/K/A next-generation WiMAX) is targeting similar numbers. Backhaul is now a bottleneck.

But while the carriers sell wireless, wireless isn't regularly the solution of choice for backhaul. Many carriers are waiting for more wireline capacity to become available. And many don't trust wireless backhaul (truly odd, when you think about it), especially using unlicensed frequencies. And most, it seems, just don't want to invest in that part of the value chain. But if 5G (if I may use that term) numbers like those above are ever to become reality (or even if 3.5G/4G systems are to have sustainable multi-megabit throughput), the carriers need to get their backhaul act together.

This may be surprising, but it's not at all unusual to find wireless backhaul systems, even those running in the unlicensed bands, today operating at hundreds of megabits per second even over 20 KM or more. There are great swaths of spectrum, including unlicensed spectrum around 5.8 GHz. and bands at 60 and 80 GHz., that are broadly available and that work just fine in this application. The real beauty of wireless for backhaul, though, is in the low cost-to-solution and rapid deployment possibilities inherent in wireless itself. Waiting for more wire is so, well, pointless.

Wireless backhaul, then, is going to become much more important going forward, as time-to-market and the need for lower costs play greater roles in carrier decision-making. I'm convinced that the carriers will make these investments, because they can't simply grow or compete unless they do. But I remain concerned that there's no real sense of urgency here, and that we poor users are likely to see increasing differentials between peak (the marketing numbers) and realized throughput as a consequence. And customer disappointment is not the path to building an industry.

It's not like this is a small opportunity - many companies build this kind of equipment. If you're interested, take a look at such firms as Motorola (which includes the former Orthogon Systems), Redline Communications, RAD Data Communications, Ceragon Networks, Harris Stratex, Dragonwave, Exalt Communications, and Bridgewave, just to name a few. A number of these firms are actually hotbeds of fundamental innovation in radio; more on that later. Regardless, addressing the backhaul challenge is on the critical path to 3.5 and 4G irrespective of what radio technology ultimately dominates in subscriber units.

• Wireless / Mobile
• Backhaul
• cellular