The world of technology has always been completive and dynamic. Innovation in the wireless area however is not simply a matter of introducing new technology or adding new services. Wireless operators need to reduce the production cost of traffic and increase capacity from existing investments for extended periods of time. The 3rd Generation Partnership Project (3GPP) family of standards- GSM (Global System for Mobile Communication), EDGE (Enhanced Data rates for GSM Evolution), WCDMA (WideBand Code Division Multiple Access), HSPA (High Speed Packet Access) and LTE (Long Term Evolution) is a proof that standardized and evolutionary solutions can meet this challenge over several decades. The 3GPP family has transitioned from basic voice and text messages to advance multimedia services over mobile broadband based on globe standards and that ensures interoperability, roaming and backward compatibility. The aligned 3GPP and 3GPP2 service providers have chosen LTE as their next generation mobile broadband technology. The 3G system goals are wide and compatibility requirements are one of its key focus areas. In 1998, wideband CDMA received strong support as UMTS terrestrial air interface for FDD frequency band. Wideband CDMA has a bandwidth of 5 MHz with high speed data rates of 144 and 384 kb/s uplink and downlink respectively. Lack of spectrum availability issues issue and offer more protection against severe multipath degradation than narrow bandwidth CDMA, increasing diversity and resulting in improve performance. Some of the WCDMA promises include multirate services, large user capacity, and interference reduction and fast power control. The 4G LTE is an excellent complement to the WCDMA network. LTE technology can be used to enhance data performance with wide-area WCDMA coverage. The first release ensures the data rate of 100Mb/s (DL) and 50Mb/s (UL), also simplified radio-network architecture design which reduces cost. LTE supports both duplexing (FDD/TDD), as well as the ability to allocate large number of different spectrum. LTE aims for 3GPP (WCDMA) and as well as 3GPP2 (CDMA2000).Various aspect of LTE encompass spectrum flexibility, multiple-antenna transmission and inter-cell interference coordination. LTE introduce the concept of physical resource block (PRB) which makes it effective in both frequency and time. This thesis investigates the physical layer techniques used to increase data rate, user capacity and reliability in WCDMA and LTE. Wide spectrum used in WCDMA and LTE is using variable bandwidth. UL (Uplink) and DL (Downlink) data modulation schemes and accessing techniques are well utilized for high data rate. Analyzing OFDMA and SC-FDMA used for reducing interference between carriers and to keep peak-to-average ratio low as to safe battery life in UL.