LTE and the backhaul challenge
LTE mobile broadband has already been rolled out in some markets and is on the verge of deployment in many more, but as data consumption grows, a challenge that will face operators is how to backhaul their LTE networks. Without enough backhaul capacity for their networks, network customers will not feel they are getting the level of service they have paid for, which is one of the prime causes for customer churn.
Today, 3G mobile broadband is commonly deployed in developed markets and provides sufficient bandwidth for basic browsing and small downloads. However, consumers often complain that more data intensive tasks, such as video streaming, are often erratic and inconsistent using 3G. LTE is being pitched as a solution to this problem but without the necessary infrastructure in place to provide sufficient backhaul capacity, operators will continue to leave customers underwhelmed.
“If operators are planning to offer 100Mbps to customers by LTE, the backhaul required would be 150Mbps or even more – and it would be over-provisioned,” said Dimitris Mavrakis, principal analyst at Informa Telecoms and Media. “Most of the deployments so far have been fibre-based, for example, Verizon’s LTE is capitalising on its fibre network, and that’s the reason why it’s so aggressive and are able to roll out LTE so quickly and in so many markets.”
But in order to provide the necessary coverage as data usage grows, operators have increasingly begun to rely on the use of small cells for their 3G networks. With small cells, operators can use many cells distributed across a geographical area to provide better coverage and satisfy customer demands.
LTE networks will need to provide speeds of up to 144Mbps to each cell. However, to deliver fibre to each small cell is not an practical option, due to the cost of leasing fibre, coupled with the work required to dig trenches to each individual small cell.
Therefore, vendors are providing fibre up to basestation towers, and then the rest of the signal is distributed by radiowave technology to the small cells. Operators can plan the contention ratio required and provide a reasonable amount of bandwidth into those radiowaves. There are various technologies on the market that aim to address this issue, and Mavrakis believes point-to-multipoint millimetre wave technology offers a compelling solution.
“Millimetre wave technology is very interesting simply because there’s so much bandwidth available so these backhaul solutions are capable of providing multi-gigabit capacity,” he said.
Bluwan is one vendor providing point to multipoint technology, and Shayan Sanyal, the firm’s CMO, believes that operators need to begin thinking about LTE small cell backhaul, as if they do not take necessary steps, their 4G networks will not deliver on the capabilities that LTE can provide.
“The reason the small cell approach is popular is because you can provide more bandwidth to fewer people,” he said. “But not a lot of thought has been given by the industry on how to backhaul small cell for LTE, so manufacturers of small cells are scrambling to figure out how to provide capacity – because the customers are saying, great technology, but how can you make it work?”
He argued that other technologies do have their use cases, but are not suitable for providing bandwidth to small cells on LTE networks. For example, point-to-point microwave requires each macro cell to have a large number of dishes installed across an area, however the installation and rental costs needed to for those dishes are very high.
“Then you have point-to-multi-point microwave, which requires almost half as many dishes, but do not provide enough capacity. Using that technology, operators can provide capacity of up to 100Mbps in total, but LTE small cells need 144Mbps delivered to each cell.”
Point to multi-point millimetre wave provides capacity of 2Gbps and can deliver 150Mbps-200Mbps to 10 sites and, according to Mavrakis, is a cheaper option too.
“It is cheaper not because of the technology itself, but because of the topology. You can put sector antennae at the distribution point, then you can connect several cells instead of having two antennae for each link,” he said.
However, he added that operators are not yet using small cells for their LTE networks, but that will be the next step of deployment and operators are likely to begin using them in one or two years.
“There’s a lot of activity from vendors on this, meaning that there’s a lot of demand from operators. Point to multipoint millimetre wave will be something to look out for,” he said.