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plex environment, SDR functionality allows operators to implement changes at the click of a button. T is makes repeaters a long-term solution to in-building coverage, rather than a temporary one.

Size matters DAS-based base stations are an appropriate so- lution for large-scale indoor deployments, but for smaller venues operators had to go back to the drawing-board in their search for cost- eff ective and effi cient in-building solutions. T ey have struggled to provide consistent cov- erage in venues of this size because aff ordable solutions with the scope to cover smaller loca- tions, which could add the additional capacity required, simply did not exist. Operators were not prepared to invest in plugging the ‘coverage gaps’ when there wasn’t a worthwhile business case to support these small-scale deployments. Building a full-sized base station to support a single, or even a multiple, operator is hugely costly and time-consuming. Meanwhile, femtocells cater only for a handful of subscribers and even those built with larger capacity require much more backhaul. T e problem is similar with picocells, which are easily overloaded if too many users require access at the same time.

In addition, with picocells and femtocells the operator relies on a network over which it has no direct control – a scenario most would prefer to avoid. T is has left mobile op- erators with a problem of indoor coverage


smaller structures. T e problem for these build- ings persists as they house a high concentration of subscrib- ers in an enclosed space.

Scaled-down solutions However, new production methods


ing technological advances in A/D converters, D/A converters and FPGAs have led to higher bandwidths, higher capacity and lower power consumption, and consequently, lower prices for these components. T is has led to core components

required for in-building

wireless technology being scaled down, so that cost-eff ective coverage solutions can be applied to small-to-medium sized

venues. T ese improvements have led to the emer-

gence of a low-cost cellular repeater which can solve a wide range of problems related to in- door coverage. T e repeater is designed to be reprogrammable so that it can be used for the frequency band and wireless technology used

LAND mobile November 2011

For next -generation deployments, a DIGImini tri/quad-band repeater – from a range by Axell Wireless

The key to LTE indoors Scaled-down indoor coverage solutions, based on digital repeaters with SDR capabilities, are now central to the provision of in-building cov- erage. Deployed strategically they can support a wide range of installations in a variety of sized structures. Firstly, a network of repeaters connected to

a DAS can deliver wireless coverage to a su- perstructure such as a shopping mall or air- port. T e compact miniature solutions can be installed to cover small-to-medium sized venues that operators previously regarded as insignifi cant.

by the operator today, and in the future. If the operator decides to increase the capacity of the serving base station by changing the band- width, the repeater can be reprogrammed to pass the increased bandwidth remotely. T is method provides the operator with a cost-ef- fective solution able to cater for the increased demand for cellular coverage in a wide variety of indoor locations Moreover, since the switch to 4G will not

happen overnight, SDR enables repeaters to cover multiple bands, simultaneously sup- porting 2G, 3G and 4G network connections. Scaled-down repeaters equipped with SDR

off er a future-proof solution in the deploy- ment of next-generation networks. Operators can simply install new software without re- placing ageing equipment when new, unfore- seen changes to radio standards are required. At the operator’s disposal is a system which can be modifi ed by software updates (without the need for any hardware upgrades) accord- ing to any changes of technology (from GSM to UMTS or LTE) or a mix of technologies.

Furthermore, advances in technology that

have allowed SDR, and other core compo- nents, to be manufactured at higher volume provide the economies of scale needed to jus- tify small-scale deployments. With the ability to remotely confi gure a network of digital re- peaters that can support a range of frequencies and sub-bands, operators can now plug every conceivable indoor coverage gap.

Testing coverage

Folllowing the completion of a large 802.11n Wi-Fi network at the Dubai World Trade Cen- tre (DWTC), a site which amounts to more than one million square feet and is visited by 1·4 million people per year, the network test- ing company Ixia was called in to verify the performance of the system. Ixia says the DWTC system’s advanced

network architecture, a testament to the growing importance of Wi-Fi as an access technology and for cellular traffi c offl oad, will increase connectivity coverage and capacity for hospitality, convention and real estate customers at the centre. Before deployment of the system, Ixia

worked with DWTC to test the system’s traffi c handling and coverage capabilities using its IxNetwork and IxLoad testing applications, together with with the newest addition to its testing portfolio, IxVeriWave. In this way, DWTC was able to verify: • the interoperability, functional and

performance tests of wireless controllers to host the expected volume of users and traffi c. Different access devices (802.11 a/b/g/n) and traffi c profi les were generated to characterize the most common access patterns (laptops, smartphones, tablets) • the access network capacity of a

conference hall. Understanding the limitation of the network in crucial areas allowed DWTC to plan effectively. • the scalability of edge and core layers.

As new services are added, it is essential to confi rm that the existing aggregation and core networks can accommodate the new traffi c demands associated to such services. • ‘quality of experience’: testing with real

Wi-Fi devices enabled DWTC to fi nd whether the quality metrics match users’ expectations. “With nearly 50 percent of the population

carrying and using connected devices, testing must go beyond a simple site survey in order to determine true capacity of the network,” said Wesam Lootah, vice president for information technology at DWTC. “DWTC was able to verify that its next-generation network performed at the level needed to provide a consistently high level quality of experience to its customers.”


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