Distributed Antenna Systems and the Evolution of Wireless Network Architectures

 

Bill Vassilakis, VP, R&D, Powerwave Technologies (www.powerwave.com)

 

 

Traditional Macro-Microcell architectures have been deployed for most of the installed 2G Infrastructure, and for newer 3G deployments. Recent build-outs in Japan and elsewhere show that greater than 85% of the sites installed are the standard high power macro cells, which are designed for providing maximum coverage and capacity in the network. As data and multi-media applications in the network increase, much more attention is focused in providing better in-building coverage and capacity and overall service quality. In addition, in certain areas, due to zoning restrictions and by-laws it is impossible to consider traditional architectures with large towers and antenna structures.


Distributed Antenna Systems (DAS) offer several advantages over traditional networks. The basestation equipment is centrally located at a convenient site where zoning may not be an issue. Trunking gain is easily achieved by changes at this central site rather than at the nodes, when more capacity is required in the network. Furthermore, the capacity can be dynamically allocated and optimized for varying traffic needs. Multiple operator network sharing can easily be employed in a DAS system, thus providing effective CAPEX and OPEX sharing. Finally, network maintenance and optimization can be continuous with minimum operating expense.

 

This year at the 2004 Summer Olympics, Vodaphone and TIM were selected to provide wireless coverage and capacity with 2G and 3G networks for the Olympic Athletic Center of Athens, also known as OAKA by its Greek letter acronym.  Network sharing was mandated by the authorities for the most part, as was equipment location, antenna type, and the required guarantee of service (GoS) for the busiest quarter hour. Additionally, network installation and optimization had to occur within very tight time requirements due to construction delays.

OAKA COMPLEX

•  1km 2 area

•  Main Stadium

•  Basketball

•  Swimming

•  Velodrome

•  Tennis


The Olympic Center included both indoor and outdoor wireless coverage environments.  The main stadium, the basketball court, and the aquatics center required a system that addressed interior coverage along with issues such as limited space for equipment, aesthetics and obstructions, not to mention difficult installation in respect to historical landmark restrictions.  The tennis courts and the Velodrome called for a system designed to meet the unique challenges presented for outdoor coverage enhancement.  The Powerwave fiber optic DAS (FODAS) solution fulfilled these requirements by overcoming additional installation challenges, such as pre-determined antenna locations and mast-pole heights dictated by the Olympic Center authorities.  Ongoing system maintenance and remote monitoring was offered via OMSSM software already in place in both of the wireless network operators' existing networks.  Plural SA of Athens installed the system and provided the ongoing system support throughout the duration of the events.  The OMS support center was located in the Plural facility in Athens, and on-site support was supplied by Powerwave and Plural engineers.

 

The FODAS system was based upon proven fiber optic and amplifier technology and effectively addressed RF attenuation issues caused by the extreme distance posed by the equipment room placement on the outside perimeter of the Olympic complex.  In addition, it provided a co-located, shared network that the two wireless network operators controlled independently. 

 

•  Multi-operator GSM/DCS sites: 45

•  Multi-operator UMTS sites: 15

•  No of Repeaters: 108
      •  18 GSM Cha. Selective

      •  81 Dual band/Single band
         GSM/DCS Selective

      •  9 UMTS

•  No of TRx GSM/DCS 480

•  No of TRx UMTS: 44

•  No of Antennas: 67

•  No of GSM/DCS BTSs 40

•  No of UMTS Node Bs 8

 

 

The system was interconnected using six fiber optic runs. The indicated blue markers are the outdoor “Microcell” locations (shown above) where antenna size and positioning was not as challenging as the indoor “Picocell” locations, where lower gain antennas were mandated.


The system was busiest on August 13th from 5 PM to 1 AM when there were 172,700 call completions. The dropped call rate was 0.39%, much better than the 1% measured in the center of Athens. More significantly, the congestion level of the system during this period was 0.05%, which in effect is equivalent to landline quality! Beyond voice, the system handled approximately 47.6 and 28.4 Gbytes of data on the Uplink (users to system) and downlink (system to users) daily. Overall, the outstanding successful implementation of the FODAS system provides a model for future network deployments that satisfy stringent CAPEX/OPEX requirements and quality of service needs.



 

Bill Vassilakis – Mr. Vassilakis is Vice President, Corporate Research and Advanced Development at Powerwave Technologies, Inc., Santa Ana, CA. His responsibilities include the planning and implementation of the technical roadmap for Powerwave.  Previously, he held high level technical positions at Nortel, Novatel, and MA/COM.  Mr. Vassilakis is a graduate of McGill University in Montreal, and is a registered professional engineer and a member of IEEE since 1985.