IDENTIFYING THE CHALLENGES
 
Cell site backhaul makes a significant contribution to an operator’s operational expenditure, and is becoming increasingly complex to manage. New base station and carrier technologies mean that there is an increasing number of possible backhaul scenarios to consider. Consequently, BT is currently submitting technical and commercial solutions and undertaking proof of concept studies that will deliver a stable and cost effective method of cell site connectivity.

Until now, cell site backhaul requirements have been largely predictable in terms of technology and bandwidth. However, new Radio Access network (RAN) technologies and business models will dramatically change this.

Traditionally, 2Mb E1 links are used for backhaul. Although technically these meet current and future network requirements, they are not scalable in a cost-effective way. (see Fig. 1). This is especially apparent for cell sites that will in future offer services to users that require high speed, asymmetric ‘bursty’ data.

Fig 1: Traffic vs. Bandwidth using E1

The deterministic and fully available nature of 2Mb TDM bearers is intrinsically costly for carriers to deliver over relatively expensive SDH equipment. Whilst the low delay, low jitter characteristics of TDM backhaul are essential for maintaining good voice quality and network synchronisation, they are not essential for the type of services envisaged for ‘the mobile Internet’ experience. For this type of traffic, a lower cost technology such as DSL may be sufficient.

Mobile operators therefore face the challenge of converging and managing various technologies to meet a reduced opex challenge today and a low cost, high growth and rapid deployment challenge tomorrow. BT wants to help operators to address this challenge by offering a managed backhaul service that will provide the right technology at the right time, to achieve the required price points and service characteristics.
 
EXPLORING THE SOLUTIONS

BT believes that an ideal backhaul service that can meet both current and near term requirements will continue to be largely based on TDM technology, augmented by DSL services as an attractive alternative. In the longer term, BT intends to deliver deterministic and non-deterministic services to accommodate 2G and 3G cell sites, based on lower cost, carrier grade Ethernet technology: PBB-TE.

To meet operators’ current cost reduction and future growth requirements, BT can offer a managed access service in a term contract with blended prices. By using tomorrow’s technology, operators can enjoy cost reductions today.

REAPING THE BENEFITS 

• Lower backhaul costs today
• Deterministic performance and appropriate SLAs
• Predictable growth in costs tomorrow