WCDMA (Wideband Code Division Multiple Access) and LTE (Long Term Evolution) are mobile communication technologies that falls under the 3rd Generation Partnership Project (3GPP) releases. LTE standards are part of the latest 3GPP releases, which are considered as 4th Generation (4G), and WCDMA is the older technology which was specified as 3rd Generation (3G) technologies. LTE release provided number of architectural changes when compared with the WCDMA network.
WCDMA
WCDMA is the European standard that fulfils the 3G specifications published by IMT-2000 (International Mobile Telecommunication). WCDMA was developed to achieve data rates up to 2Mbps in the stationary environments, while 384kbps in the mobile environment. WCDMA uses pseudo random signal to modulate the original signal into a higher bandwidth, where original signal sink in the noise. Each user will get a unique pseudo random code to separate the original signal from the air interface. WCDMA uses Quadrature Phase Shift Keying (QPSK) as modulation scheme, while using Frequency Division Duplexing (FDD) as duplexing method. WCDMA architecture consists of separate Circuit Switched (CS) core network and Packet Switched (PS) core network. CS core consists of Media Gateway (MGw) and MSC-S (Mobile Switching Centre-Server), while PS core consist of Serving GPRS Support Node (SGSN) and Gateway GPRS Support Node (GGSN). Radio access network of WCDMA consists of Radio Network Controller (RNC) and Node-B. In here, RNC integrates with MGw and SGSN for CS data and for PS data respectively.
LTE
LTE was introduced in 3GPP release 8 in December 2008. LTE uses Orthogonal Frequency Division Multiplexing (OFDM) for downlink, and Single Carrier Frequency Division Multiple Access (SC-FDMA) for uplink access. LTE Category 3 user equipment should support up to 100Mbps in downlink, and 50Mbps in uplink. LTE has a more flat architecture with eNode-B, System Architecture Evolution Gateway (SAE-GW), and Mobile Management Entity (MME). eNode-B connects with both MME and with SAE-GW for control plane data transfer (Signalling), and for user plane data transfer (user data) respectively. LTE was able to achieve high spectral efficiency with OFDM, while providing robustness for multipath fading. LTE supports services like VoIP, Multicasting, and Broadcasting more efficiently than the previous 3GPP specifications.
What is the difference between WCDMA and LTE?
WCDMA was specified in the 3GPP release 99 and 4 of the specification, while LTE was specified in the 3GPP release 8 and 9. Unlike WCDMA, LTE supports variable bandwidth from 1.25MHz to 20MHz. When the data rates are compared, LTE provides massive downlink and uplink speeds than WCDMA. Also, the spectral efficiency is much higher in LTE than that of the WCDMA. LTE provides much simpler and flat network architecture than that of the WCDMA. CS core network part of WCDMA, which includes MGW and MSC Server is completely replaced by PS core in LTE using the SAE-GW and MME. Also, the PS core nodes of WCDMA that consists of GGSN and SGSN are replaced by the same SAE-GW and MME respectively. RNC and Node-B nodes in WCDMA architecture are completely replaced by more flat architecture with only eNode-B in LTE. New interface between eNode-B’s are introduced in LTE, which is not available under WCDMA. LTE is more optimized for IP packet based services; there is no circuit switch core with the WCDMA. LTE provides more flexibility than that of WCDMA when comes to network topology and scalability. In general, WCDMA is considered as 3G technology while LTE is considered as 4G technology.
LTE provides higher data rates than WCDMA by achieving higher spectral efficiency. Also, LTE technology provide more flat architecture that is mainly focused on IP packet based services than that of the WCDMA. LTE topology is much more flexible and scalable than of the WCDMA due to the flat nature of architecture.