• United States
by Roger Quayle, special to Network World

Technology delivers high data rates

Mar 06, 20063 mins

An emerging mobile broadband technology can deliver high-speed data services to workers wherever they are.

UMTS TD-CDMA, or Code Division Multiple Access – also known as UMTS TDD – is an air interface technology that is part of the 3rd Generation Partnership Protocol (3GPP) family. It was designed to provide high data rates and capacity for data and voice. Leading mobile operators worldwide have deployed it commercially.

UMTS TD-CDMA is a time-division-duplex (TDD) technology, in which the uplink and downlink transmissions alternate on the same radio-frequency channel. This is achieved by allocating time slots to the uplink and to the downlink, with the ratio determining the relative uplink and downlink bandwidth.

Two-way channel sharing

As a 3GPP standard, UMTS TD-CDMA is designed to support packet data (IP), circuit switched voice, and VoIP with QoS. To provide this support, 3GPP TDD implements shared channels and dedicated channels. Unlike WCDMA, a 3GPP technology that supports only dedicated channels on the uplink, TD-CDMA supports shared channels in both directions, making it ideal for packet-based applications and more efficient dealing with the busy traffic that is characteristic of the Internet.

UMTS TD-CDMA adapts to the radio channel environment, with the objective of delivering the highest possible data throughput that the channel will support at a particular time. The standard defines a flexible transport-format concept, in which each transport format is a particular combination of modulation and coding, to deliver the best possible burst data rate.

UMTS TD-CDMA lets operators implement full packet inspection and prioritization capabilities on their networks, extending the benefits of an IP core to its 3G air interface. As such, operators are able to offer enterprises a new set of differentiated mobile broadband services, full network QoS on a service-by-service basis, and improved performance of real-time applications.

Premium corporate, VoIP, gaming or video applications can be assigned the ideal network resources and will not be affected by network congestion during peak traffic times, while peer to peer or other bandwidth-intensive but latency-insensitive applications are held back.

UMTS TD-CDMA is designed to work in a wide range of environments, including vehicles moving at speeds greater than 80 mph. In less demanding portable and fixed environments, the technology has even higher performance. This is a significant advantage over fixed wireless solutions such as WiMAX, DSL and cable.

Some of the key benefits of UMTS TD-CDMA include:

l High speed through the network: Offers true multimegabit broadband speeds without any deterioration in performance at the cell edge, which means mobile workers don’t have to wait for large files to download.

•  Faster uplink speeds: This lets mobile workers send, or upload, large files more quickly.

•  Less network congestion: As a pure packet-based network, UMTS TD-CDMA can support more simultaneous users, resulting in less network congestion.

•  Mobility: Offers ubiquitous connectivity that allows access from home, office, outdoors or moving anywhere within the network.

•  Better response times for real-time applications: Provides the highest throughputs of any wireless broadband technology and very low network latencies – 45 to 70 msec, making possible popular applications such as videoconferencing and VPNs.

•  Security: UMTS TD-CDMA uses the same security information-management authentication as WCDMA, making it secure for enterprise data communications.

As the size of the mobile workforce continues to grow and the United States moves toward ubiquitous mobility, the demand for technologies that can deliver data at broadband speeds but with the benefit of mobility will increase exponentially. UMTS TD-CDMA is an ideal solution for mobile workers who need to access large files on the go.

Quayle is the CTO of IPWireless. He can be reached at

UMTS TD-CDMA enables mobile subscribers to connect to the Internet or access multimedia at broadband speeds.