Cellular Base Station Installation & Maintenance Challenges

CellAdvisor Solutions Marketing at Viavi Solutions looks at some of the challenges facing the set up and maintenance of mobile base stations.
Up until relatively recently, much of the real radio equipment at a cell or telco network cell tower was safely and conveniently stored in the cabinet on the ground or near to the foundation of the site. A coaxial cable connected the radio gear to the antennae at the top of the tower.

This meant that the installation crew, and particularly the cell tower riggers, could check the quality of the RF signal being received in the cabinet without the need to climb the tower.

Of course, plenty of the maintenance required at the tower would still involve a climb, especially if the check on the RF signal at ground level showed a fault, but a good number of checks could be carried out on the ground.

Today’s maintenance challenges
Fast forward to today, and the situation is changing. Modern cell sites use a distributed architecture in which Baseband units (BBU) are either located at the foot of a tower or located at a remote distance at a BBU hub. In this case it is likely to serve not just the antennae at the top of that tower, but a chain of other towers as well. What’s more, at the top of each of those towers, close to the antenna array is the Remote Radio Head (RRH) which contains the actual radio equipment (RE).

To add to the complexity – but also improve signal Curso Conserto de Celular quality – instead of traditional coax cable, fibre is frequently used to connect the RE equipment in the RRH to the other radio heads and to the REC gear at the BBU hub, serving the towers.

Today, riggers installing and checking the sites, often need to climb the towers with full pack of advanced technical test equipment, as well as the more physical tools of their trade – such as spanners, wrenches, hammers and multiple screwdrivers.

Recently we spoke to cell tower riggers in both the USA and the UK, looking to get a feeling for how difficult their jobs had become, and what companies like ours could do to make it better. In many ways, the riggers are the unsung heroes of the telecoms world, carrying out highly specialised tasks in often dangerous circumstances and challenging environmental conditions.

Each day, their role can involve a multitude of tasks such as installation, commissioning and decommissioning, dismantling and removal of equipment from great curso manutenção celular heights be they masts, towers, pylons or rooftops. They are also involved in the earthing, labelling, and testing of feeder cables and optical fiber; as well as the inspection and testing of Outdoor Units (ODUs), Indoor Units (IDUs), Splitters and the CPN testing and auditing of rigging set up. The list is endless.

Small wonder then that more than three-quarters of the riggers we spoke to said that they now needed between 20 and 50 per cent more time at each site to carry out the required maintenance work. What’s more, some 67 per cent of UK riggers believe their job is becoming more and more complex with almost half of the riggers adding that it has become both costly and dangerous to carry out testing at the top of a tower. Hardly surprising either that having lighter, and easier to carry equipment was high on the rigger’s wish list, alongside machines that could perform multiple tasks – preferably from the ground.

Distributed architectures
The move to a distributed architecture with the RF units much closer to the antennae and the use of fibre to link the equipment has undoubtedly boosted signal quality and improved performance. But the riggers could be seen to be the ones paying the price – especially as all the RF functions for each tower are at the RRH meaning that interference analysis needs to be undertaken at the top of the tower. That means higher operational costs and increased security concerns.

The role that standards have to play in tackling these challenges and making life easier for the riggers should not be underestimated. The major network equipment vendors – including Ericsson, Huawei, NEC, and Nokia (which now includes Alcatel-Lucent) – co-operated to define a specification for the communication between the BBU and the RRH. The specification, known as the common public radio interface (CPRI) has quickly become the industry standard for the internal interface between cell towers in a distributed architecture.

The same companies, together with ZTE and Samsung, also worked together on the Open Foundation Station Architecture Initiative (OBSAI) which defines a set of specifications underpinning the architecture, functions and minimum requirements for integrating common modules in a mobile network foundation station (BTS). In particular, this governs the interchange of user and signalling data between the BBU and the RRH.

Standards for these types of interfaces might be driven by operators wanting to multi-source equipment but the difference they make to the riggers’ job in terms of maintenance and troubleshooting should not be under-estimated either.

The CPRI interface was also specifically designed to help enable flexible cell site architectures by defining a serialised interface to allow for the different topologies of network – be they simply chained, a tree and branch configuration, or a ring network. The development of a mechanism and process to analyse the RF performance of multiple RRHs from the BBU hub is one significant step forward that can increase maintenance efficiency and reduce the number of tower climbs required.