Wideband Code-Division Multiple Access (WCDMA) is basically a third-generation (3G) mobile technology system. It is a wireless technology which promises high data speed to various mobile and portable wireless devices available in today’s market. Generally, it can support transmission of image, voice, data, and video at a speed of up to 2Mbps (for local area access) and 384Kbps (for wide area access). Technically, the input signals are digitized and coded. They are then transmitted in a broad range of frequencies. Compared to narrowband CDMA (which uses a 200KHz-wide carrier), WCDMA system uses a 5MHz-wide carrier.
In WCDMA networks, the CDMA air interface is combined with GSM network. The standard for this system evolved to ensure interoperability between different 3G networks. Within this network, there are two possible modes of operation: (1) TDD: uplink and downlink transmissions are carried over the same frequency by different time intervals. Time slots are therefore divided into reception and transmission part. (2) FDD: uplink and downlink transmissions are carried by different frequency bands. Since different regions allocate frequencies differently, the ability to use both TDD and FDD allows optimal use of available spectrum of transmission. This system also has built-in support for better future technologies (capacity and coverage-enhancing) like transmitter and antennas. Inter-frequency and transfer to other systems (i.e. GSM) is also very convenient.
The WCDMA networks are based on radio access technique and one of the main technologies of 3G mobile system. Full implementation of this system, however, is limited due to its complexity and versatility. For example, the overall system is configured from complex algorithms. Different users can simultaneously transmit data and users can receive them in different times. Compared to 2G technology, this system is 10 times more compute-intensive. Therefore, as this system is gaining popularity, it helps to know what the future may hold in mobile development and data transmission technologies.
