Telecom network maturity and service demand vary around the world, and differences can be seen even within countries. Currently, all networks globally are witnessing intense data growth. In order to meet the data requirements, there is an urgent need to upgrade the existing backhaul transmission infrastructure in sync with radio technologies (2G, 3G, 4G, 5G, etc.).

Capacity and coverage requirements are leading to the adoption of new and revolutionary approaches for mobile backhauling in urban and sub-urban environments. Data usage is expected to increase by six times over the next three to four years. Given the very high capacity requ­ire­ment, a backhauling technique must allow capacity enhancement and spectrum efficiency while keeping power consumption low. Operators are aware of the growing capacity requirements and want to provide the best possible performance and quality of experience in the most cost-efficient manner.

What is mobile backhaul?

The mobile backhaul network provides connectivity between the radio base station site and the switch site at the edge of a transport network. It starts at the cell site and ends up in the mobile core. So everything in between the base transceiver station/NodeB/eNodeB and the core network is considered as mobile backhaul.

It has two subdivisions – fibre and wireless. Wireless backhaul is further divided into microwave and millimetre (mm) wave. These are vital network components that enable operators to interconnect various nodes. Wireless is the dominant backhaul technology, and is expected to remain so in the future.

Further, mm wave has two main technologies – E-band and V-band. Given the different nature of the two frequencies, different scenarios can be foreseen for each of them. These include macro and small cell backhaul, front-haul applications, and line of sight (LoS) at present and near LoS or non-LoS in the future. Nonetheless, regulations for these two frequency bands are not always defined, opened and planned, especially in the case of V-band, wherein the related portions of spectrum differ from country to country making it very fragmented.

Characteristics and nature of E-band spectrum

E-band enables gigabit per second data rates, given the huge amount of available spectrum (10 GHz) without any oxygen absorption. It is intended to cover 71-76 GHz and 81-86 GHz frequencies. Since the current traditional frequencies below 50 GHz are already highly crowded and exploited, there is a need to use higher frequency bands to future-proof networks. Due to technology evolution and the availability of wide channel bandwidths, the use of spectrum in E-band appears to be of interest for the current and future needs of backhaul networks.

Advantages and applications of E-band

The 71-76 GHz and 81-86 GHz bands are used for ultra-high capacity point-to-point communications. The advantages of E-band are its wide spectrum (10 GHz) and its channels that allow very high capacities similar to the fibre-like bandwidth in Gbps. E-band offers the highest data rates for any wireless technology, with systems that offer 1 Gbps and above full-duplex throughput. Meanwhile, improvement in modulation from 512 QAM to 4096 QAM enhances spectrum efficiency by 30 per cent in the traditional band. The adoption of E-band for high throughput in urban areas with high data demand is also extremely beneficial.

Due to its high capacity, E-band complements fibre by providing a high throughput of 2.5 Gbps, which can even go up to 5 Gbps with polarisation techniques. Further, with the launch of 3G/4G services, the backhaul demand cannot be met solely by traditional systems; E-band supplements these. E-band also solves the spectrum congestion problem in urban/sub-urban areas where spectrum is slowly running out. It can also be used for small cell backhaul.

In sum

E-band can provide gigabit Ethernet data rates of more than 1 Gbps over several miles, irrespective of weather conditions, ensuring cost-effective radio architectures. Moreover, the technology has been proved to be very helpful in connecting small cells in urban areas where the installation of fibre is difficult. Considering all these factors, E-band technology seems to be very favou­­rable to cope with high data demand in all areas.

Based on a white paper, “The Next Generation Backhaul Networks – E-band”, published by NEC in August 2016