Home Latin America 2005 Cellular’s evolving RF palette

Cellular’s evolving RF palette

by david.nunes
Jörg SpringerIssue:Latin America 2005
Article no.:7
Topic:Cellular’s evolving RF palette
Author:Jörg Springer
Title:Chief Marketing Officer
Organisation:Radio Frequency Systems
PDF size:140KB

About author

Jörg Springer is the Chief Marketing Officer with wireless technology group Radio Frequency Systems (RFS). He has over 15 years of experience in global marketing and business development and management. Mr Springer has been responsible for strategy and budget development, as well as product, brand and corporate marketing. He has held executive positions in Europe, North America and Mercosul, such as Corporate Director of Product Line Communications with a multinational European OEM and Head of Business Development with a Brazilian group based in Rio de Janeiro. Mr Springer joined RFS as Marketing Director for Europe, Middle East and Africa, moved on to become Global Director of Public Relations and then was promoted to Vice President Global Marketing/Chief Marketing Office (CMO). Jörg Springer holds a Masters degree in Business Administration (MBA), with majors in foreign trade and international marketing and management.


Article abstract

In much of the world, including Latin America, there are more wireless than wireline subscribers, so third-generation (3G) wireless data access is especially important. 3G wireless uses CDMA technology, which has different propagation requirements than existing GSM and TDMA installations. To maximise performance of existing systems and migrate to the new, operators are using radio frequency conditioning systems and intelligent antennas to provide the precision control of cell footprint size, shape, direction and power that CDMA systems need.


Full Article

‘An environment of change’ accurately describes the cellular communications world. In the 1990s, mobile telephony was essentially a voice service largely limited to Western Europe, North America and Japan, where together 70 per cent of the world’s 320 million mobile subscribers were located. Today, while voice remains an essential revenue earner, mobile data is the major growth market. Today, cellular is truly global, with the most significant subscriber growth seen in Brazil, China, Eastern Europe, Africa and India. Until the end of the 1990s, cellular average revenue per user (ARPU) was healthy and yearly subscriber growth approached 50 per cent in most regions. Operators and OEMs operated in distinct, usually localised, geographic areas. The same ‘boundaries’ constrained cellular technology selection. Significant regulatory changes in the 90s changed this. The USA’s Federal Communications Commission (FCC) opened the door to competition by disbanding the mobile cellular duopoly and introducing its 45-MHz ‘spectrum cap’. Soon after, the World Trade Organisation’s ‘international telecommunications treaty’ exposed operators in signatory countries to global competition. Free trade and unbridled competition had arrived in the major telephony markets. Cellular ARPU growth slowed due to global competition and pre-paid services and operators sought ways to expand market share and reduce operational expenditures. Despite the challenge of global competition, many operators and OEMs saw opportunities to explore markets outside their traditional ‘patch’. In parallel, the emerging economies of Brazil, China, Eastern Europe, Africa and India identified mobile as a means of fast-tracking telecommunications infrastructure development, which had long stagnated under monopoly rule. Cellular was on its global growth path. The drive for data In the developed markets, interest grew in third-generation (3G) cellular. 3G’s data-based mobile services, always-on Internet connectivity, email, video telephony and streaming video proved increasingly attractive in an industry with flagging ARPU and slowing subscription rates. 3G called for new wireless technologies that supported packet-switched, rather than circuit-switched, high-speed data. In 1999, the International Telecommunications Union sanctioned five technical standards for 3G mobile. Two now dominate, both code division multiple access (CDMA)-based: wideband CDMA (W-CDMA) as the migration path for global system for mobile communications (GSM) networks and CDMA2000 for CDMA systems. W-CDMA, now deployed in a new 2.1 GHz spectrum band in Europe and parts of Asia, demands new base transmitter station (BTS) sites. Since fresh sites were already rare, multiband (GSM 900 MHz, GSM 1800 MHz, W-CDMA 2100 MHz) and broadband antenna solutions were needed. CDMA2000 though – essentially a BTS software and channel card upgrade for existing 2G CDMA networks – does not require new spectrum. Both technologies required new handsets, with new chip sets, and a suite of new services. The move from time division multiple access (TDMA)-based GSM to a CDMA-based technology presented GSM operators with network management challenges. Whereas TDMA minimises co-channel interference by reusing a select number of channels over a group of cells, CDMA-based systems use the full frequency band in each cell. Moreover, CDMA cells ‘breathe’ – their size varies with the number of callers within the cell, data rates and so on. The resulting co-channel interference in the CDMA-based network increases network ‘noise’ and progressively depletes network capacity. CDMA presents tougher network planning than GSM, particularly in addressing CDMA’s soft handover/capacity trade-off. This called for cellular antenna solutions with sufficient flexibility for CDMA needs including precision control of cell footprint size, shape, direction and power. To compensate for CDMA-style cell breathing and often less-than-optimal site locations, variable electrical tilt, to continuously adjust cell footprint size, was necessary. Wringing more from 2G The US$73 billion spent on W-CDMA spectrum licenses in Germany and UK alone slowed European 3G rollout. Rollout was also slowed by protracted delays in advanced CDMA handset and chipset availability, regulatory indecision regarding the sharing of 3G infrastructure and, in the USA, about additional spectrum for 3G. To meet growing subscriber demand with existing 2G infrastructures, operators struggled to optimise network performance and wring more from decade-old 2G assets. This generated demand for high-performance antenna systems as an intermediate solution. In the meantime, 2.5G cellular solutions such as enhanced data rate for GSM evolution (EDGE) served to bring some data services on stream. The transition to 2.5G and 3G thrust RF conditioning (RFC) technologies – filters, duplexers and tower mounted amplifiers (TMAs) – into the spotlight. Increasing network overlays and retrofits generated operator interest in advanced RFC solutions. Initially, TMAs were in high demand, but demand diminished as 2G BTS sensitivities improved. The importance of maximising subscriber bit rate in a 2.5G and 3G scenario changed all this: unlike voice services, subscriber bit rate changes according to the received power at the BTS. EDGE, CDMA2000 and W-CDMA coverage was slim in the earliest deployment stages, as the uplink limited the bit rate. TMAs were the answer. Since the informal geographic ‘boundaries’ governing mobile technologies were abandoned in the late-1990s, and new, untried, cellular overlay combinations have been deployed – the spotlight is now on RFC solutions. China Unicom, for instance, overlaid CDMA 850 MHz on its GSM 900 MHz network, while in Brazil they overlaid GSM 900 MHz on established CDMA 850 MHz networks. These new combinations generated unexpected cross-platform interference problems and led to a new generation of precision-engineered and customised co-location filtering technology. Flexibility and remote control The major global operator groups showed particular interest in the escalating markets of Latin America, Africa, Eastern Europe, China and India. This created demand for broadband and multi-band antenna solutions that addressed broader markets, including the first triple band antenna with independent fixed electrical tilt in each band and with beam apertures expanded to 90 degrees, to rationalise and reduce antenna inventories. It is now clear that control of variable electrical tilt and other antenna parametres needs to be remotely accessible. The Antenna Interface Standards Group (AISG) developed a standard antenna communications protocol and physical interface for such control, ratified by the 3G Partnering Project, which is now the global standard for tower top device monitoring and control. A typical AISG-compliant solution incorporates a remote electrical tilt antenna control unit (ACU), a tower mounted amplifier, bias-T, plus a control network interface unit. The ACU and TMA have evolved to become, at least conceptually, part of the antenna. ‘Integrated antennas’ fit and concealed both TMA and ACU within a single body. Next, the antenna and RFC will morph into a single powered entity called an ‘active antenna’. These antennas are no longer passive, dumb, devices. They are powered active devices often fitted with onboard intelligence and control. Tomorrow’s antennas Tomorrow’s antennas will integrate a wide range of active RF conditioning components, such as low-noise amplifiers, multiplexers and filters, with increasing levels of control, that might be corrected by simulation tools in closed-loop real-time configurations. The network might ultimately be able to adjust the antenna beams and RFC parameters to minimise interference and maximise subscriber bit rate. These super-flexible solutions will be instrumental in establishing ubiquitous wireless data services globally. Cellular will be ubiquitous in the future. In developing markets such as Brazil and India, wireline connections have stalled and wireless connections now greatly outnumbered them. The challenge is to focus on the rapidly changing market and extend the RF palette of offerings to achieve greater flexibility and performance.

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