Telefonica CDMA Mobile Telecoms Network, Brazil
Towards the end of 1998, Lucent Technologies won a contract to supply Grupo Telefonica, the Spanish telecoms group, with a new code division multiple access (CDMA) mobile telecoms network for construction in Brazil. The project was initially intended to serve the states of Rio de Janeiro and Sergipe - a combined population of around one million. The CDMA network launched in 2000. Telefonica Celular subsequently invested in CDMA2000 1x equipment with network launch in Rio de Janeiro in April 2002.
Lucent Technologies is Telefonica's preferred technology supplier. It has completed extensive projects with the Spanish telecoms group across Europe and Latin America. To further cement the relationship, Lucent took 50% of Telefonica's share in Amper, Spain's largest manufacturer of telecommunications equipment, for $49 million in January 1999. Lucent Technologies has proved highly successful in the Latin American CDMA market, winning contracts to build CDMA networks in Mexico, Venezuela, El Salvador, Puerto Rico, the Dominican Republic and Guadeloupe.
THE CDMA NETWORK
Rio's new CDMA network is built upon Lucent Technologies' 5ESS AnyMedia switching platform, and the Autoplex System 1000 Series II cell sites. Lucent is also supplying technical expertise, along with professional and support services. Lucent's 5ESS AnyMedia Switch is a large-scale digital switching system that will integrate the mobile network with the fixed-line network and provide the ability to handle mobile subscribers. Analysis from the US telecoms regulatory body, the Federal Communications Commission (FCC), at that point in time stated that the switch was the most reliable on the market.
The Autoplex System 1000 Series II platform uses CDMA, a digital wireless technology based on the IS-95 air interface. CDMA provides increased call capacity and enhanced call quality, comparable to a land line service. It reduces the static and cross-talk sometimes heard on analogue systems, and provides a soft hand-off capability that makes call handovers between cell sites and mobile switching centres unnoticeable to customers. The digital cell sites for this project were manufactured at the Lucent manufacturing facility in Campinas, Brazil.
TELEFONICA CELULAR CDMA2000 1X MOBILE NETWORK
In April 2002, Telefonica Celular launched its first CDMA2000 1x high-speed mobile network. The network runs on Lucent Technologies equipment in the Rio de Janeiro area, achieving data transmission speeds of up to 153kbps (kilobits per second). The Lucent delivery included base station upgrades with CDMA2000 1X channel cards and software, software upgrades for the operator’s mobile switching centres as well as additional Lucent Flexent® base stations.
With CDMA all users share the same 1,250kHz wide carrier, but unique digital codes are used to differentiate subscribers. The codes are shared by both the mobile station and the base station and are called pseudo-random code sequences. Base stations in the system distinguish themselves from each other by transmitting different portions of the code at a given time. In other words, the base stations transmit time-offset versions of the same pseudo-random code.
In order to ensure that the time offsets used remain unique from each other, CDMA stations must remain synchronised to a common time reference. The global positioning system (GPS) provides this precise common time reference. GPS is a satellite-based radio navigation system capable of providing a practical and affordable means of determining continuous position, velocity and time to an unlimited number of users.
One of the unique aspects of CDMA is that while there are certainly limits to the number of phone calls that can be handled by a carrier, this is not a fixed amount. The number of simultaneous connections any base station is able to handle is the result of a trade-off with the range of the base station and the quality of each connection. A standard CDMA connection has a digital transfer rate of 9.6kbps, the same as GSM. The voice data part of the connection is transmitted at a rate of 8kbps. All connections are shared around the spread spectrum with a maximum transfer rate of 1.23Mbps (Megabits per second), theoretically allowing a maximum of 131 connections, compared to 48 GSM connections in a similar bandwidth.
CDMA supports variable bandwidth connections, with enhanced standards at 13kbps and 64kbps for superior quality speech and faster data connections. This "bandwidth-on-demand" limits the number of simultaneous connections to a particular base station.