Just what is backhaul and why does it stand in the way of mobile services? Backhaul, as the term is used now, means the connection from the wireless tower site back to the provider’s central office or mobile switching center.
Backhaul is something you didn’t hear much about until recently. As cellular sites were originally envisioned, they consisted of a radio transmission system with spectrum divided into multiple channels. Those channels are used to communicate with the wireless handsets to transport telephone conservations. The backhaul system consists of T1 lines that offer up to 24 individual phone lines on a digital trunk.
The beauty of T1 lines is that they are provisioned on ordinary twisted pair copper. That’s right, they use telephone line. Each T1 requires two copper pair. But instead of carrying two phone conversations, the digital line can carry 24 conversations. That’s an efficiency improvement of 12x over analog telephony. Because they use ordinary telco cabling, T1 lines can be easily provisioned to both rural and urban tower sites.
T1 lines can also be used to carry broadband Internet services. Many businesses get their broadband service over a T1 line. All cellular phone companies need do is provide a data T1 line to the tower site and use some of the available wireless channels for Internet service. That gives the user both voice and data on their mobile device.
Everything worked smoothly until newer cell phones, especially the large touch screen models, made streaming audio and video and HTLM Web browsing possible. Video chews up bandwidth like crazy. If people expect to have a television watching experience on their cell phone, the cellular transmitters are going to need bandwidth and lots of it.
This is what’s underway now. The initial response to the increase in bandwidth utilization was met by bonding multiple T1 lines to create bigger bandwidth pipes out to the tower sites. But wireless broadband speeds are increasing by leaps and bounds. AT&T’s HSPA service for 3G mobile wireless offers a max download speed of 3.6 Mbps. They are currently in an upgrade mode to double that to 7.2 Mbps. The next generation technology is 4G using LTE that will offer speeds over 10 Mbps. Sprint and Clearwire are busy building out WiMAX, another 4G technology. Verizon is running EV-DO Rev A for it’s 3G network and will implement LTE for 4G, similar to AT&T.
What this means is a big demand for backhaul service to get the voice and data signals to and from the tower sites. Carrier Ethernet can address some of this demand over multiple copper pair. WiMAX is touted as both an end-user broadband service and a backhaul technology. It just depends on where the signals go. Ultimately, fiber optic cable is the solution to the backhaul bottleneck. Fiber has nearly unlimited capacity, but it is expensive to install where there is no fiber today.
It seems like there should be some synergy between the rural broadband initiative being pushed by the Federal Government and the need for higher bandwidths to carrier-owned cellular facilities. Why not just bite the bullet and get fiber to the boonies now? It won’t be long before that massive bandwidth is going to be a necessity rather than a luxury.
In the meantime, if you have a need for voice or data bandwidth for any business application, see what bandwidth options are available for your location. You may be surprised at how much you can get at a reasonable price these days.