Delivering sky-high mobile bandwidth

As 4G connectivity becomes an ever-nearer reality for subscribers in the Middle East, Vick Khalil Mamlouk, VP of Middle East and Africa, CommScope, explains how in-building solutions can ensure flawless next-generation connectivity in even the tallest of skyscrapers

Etisalat’s LTE network in the UAE became the first commercial LTE network to be deployed in the Middle East and, where they have ventured, others will soon follow. Zain aims to deploy LTE networks over the next two years in Bahrain, the UAE, Saudi Arabia and Jordan, while Etisalat also plans to enhance its LTE footprint across the region. Soon many of the region’s cities will have the mobile connectivity to reflect the state-of-the-art skyscrapers and hi-tech commercial hubs for which they’re known.

These dense, highly populated urban areas are where we see the most mobile data consumption. In fact, we find that in many countries approximately 70% of the traffic on cellular networks originates from or terminates inside buildings. Unfortunately, these same structures can often present significant technical hurdles as signal strength may be drastically reduced when penetrating physical structures. Clearly this is an important obstacle for operators to overcome, as they strive to deliver the bandwidth and user experience expected from a next-generation network.

We’ve been involved in numerous LTE trials with major global operators over the last 2 years, including projects in the Bhurj Khalifa, and have seen how in-building systems can deliver near-flawless next-generation performance indoors. But it’s not just in skyscrapers where in-building solutions are required, the same benefits can achieved in all major business hubs, large public transport systems, stadia and high-rise residential and business buildings.

By providing dedicated next-generation communications to the sites where much of the demand for additional bandwidth is concentrated, operators can maximise their LTE revenue streams as quickly as possible. In addition, by having a dedicated high speed network in place, the impact of these sites on surrounding networks will be substantially reduced, which has the knock-on benefit of freeing up valuable network resources elsewhere.

Achieving LTE indoors

Currently, dedicated indoor coverage and capacity is provided through Distributed Antenna Systems (DAS), where radio frequency (RF) signals are routed through fibre or copper cabling from a single base station to multiple antennas located throughout the building. This has proven to be a highly effective and efficient way to distribute wireless connections inside a large building and eliminate ‘dead zones’, as steel columns and layers of concrete can interfere with wireless signals.

Fortunately, the same principles can be applied to a DAS providing LTE coverage, allowing operators to confidently roll the system out using established protocols and, in some cases, existing infrastructure. By adapting a DAS system that already provides 2G or 3G coverage inside a building to provide LTE, it is possible to substantially reduce the capital expenditure when compared to a brand new installation. Of course, each building and each legacy DAS will have their own unique requirements to make the switch to LTE, but much of the knowledge, equipment and technical expertise is already in place.

Next-gen considerations

The main design criteria for an LTE in-building DAS is a question of cost versus performance. Most existing in-building solutions use a Single Input Single Output (SISO) system, which can be adapted to the Multiple Input Multiple Output (MIMO) system required for LTE coverage. This avoids major construction activities, such as opening up the ceiling to bring in a second cable path, but each project will need to evaluate whether a simple reconfiguration of the SISO will provide sufficient performance.

To help illustrate the performance of various in-building solutions we used our test facility – a standard square office floor with corridors – to compare four DAS scenarios and provide a general guide into their data rates in the same environment:

  1. Co-located pair of antennas: The most straightforward approach to upgrade indoor coverage involves installing a MIMO antenna next to a standalone SISO instalment. In our test environment this achieved a data rate of 61 Mbps throughout 91% of the floor.
  2. Distributed antennas: By splitting up the co-located antennas and installing the SISO and MIMO antennas on opposite sides of the floor, we were able to ensure that the data rate never fell below 75 Mbps across the whole floor.
  3. Distributed pair of antennas: If there are existing distributed SISO antennas in place, it is relatively simple to install two additional MIMO antennas in the same positions. This achieves even higher and more consistent data rates at a minimum of 112 Mbps.
  4. Interleaved distributed antennas: The most elaborate alternative is to install two additional interleaved antennas, which would require a change in the position of the existing antenna locations as well. From a MIMO performance point of view this is the optimal solution, achieving a minimum of 117 Mbps across the floor.

From a business and performance point of view, the reasons for implementing LTE in-building solutions are evident. It provides optimum levels of performance and gives operators the perfect opportunity to make the most of their investment in the network, helping to accelerate deployments elsewhere. From a technology perspective, it is merely a question of assessing individual sites to help determine the cost of implementation versus performance. Once a decision has been made, then it’s simply a case of implementing tried and tested solutions.

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