Network timing and synchronization used to be fairly straightforward. Basestations were connected using 2Mbps links synchronized to a central master clock. Expensive OCXO crystals costing several hundred dollars or more provided holdover times of many hours, allowing almost instant recovery after outages of hours or more. In many networks, a single technical designer might be responsible for the synchronization across the network on a part-time basis.
The enormous growth in mobile broadband data is leading to growing numbers of small cells, especially Metrocells, connected using IP/Ethernet backhaul. This, combined with the introduction of stricter timing requirements for LTE and LTE-Advanced, has some implications for the choice of wireless backhaul technologies used. Here, we explain the technology and discuss the alternatives.
Small Cell Wireless Backhaul for Metrocells has attracted a lot of attention in recent months, with vendors launching new products, introducing new technologies and agreeing new sales channels.
Esteban has been tracking small cell backhaul developments for some time. He pinpoints why and where wireless backhaul will be critical for metrocells, highlights the key factors/requirements driving the choice of technology, and reveals some technical limitations of today's products.
Richard Deasington, Director of Market Development at iDirect, believes that recent developments in satellite technology combined with small cells will make rural 3G mobile service viable even for smaller communities. We asked him why this is the case, why it's not just relevant to developing countries and what the industry is doing to extend 3G service to off-grid places today.
Backhaul for many public access and some enterprise small cell deployments involves a wireless link for the last few hundred metres. It may not be feasible to connect fibre in every case, both because time and cost are prohibitive. One of the choices for that last hop is point-to-point microwave operating at 60GHz (
Residential and Enterprise femtocells are normally connected by traditional broadband internet service, using DSL, cable modem or enterprise-grade broadband. Public access small cells, on the other hand, are usually installed and managed by the network operator themselves. This means they have to design and deploy a backhaul network suitable for the task. It must be high enough capacity to meet the demands of multi-mode 3G/LTE small cells, yet cost effective to be viable. As if that wasn't enough, it must not constrain the location of the small cells and be easy to install by non-specialist staff.
