Implementation of Compressed Mode in UMTS for 3G Smartphones

Due to increase of data browsing and downloading using 3G enabled mobile handset, it is often required handover mechanism from Universal Mobile Tele-communication System (UMTS) to UMTS, Long Term Evolution (LTE) or Global system for Mobile Communications (GSM) while the handset is continuously transmitting and receiving data from the connected Node-B in a high speed motion. In UMTS, the handheld device contains only one receiving antenna, which cannot measure the neighboring cell power (RSCP) while Packet Switched (PS) mode is enabled and active. Compressed mode (CM), also known as slotted mode is a technique used in UMTS, when a User Equipment (UE) wants to measure other frequency (inter-frequency) or different radio technology (inter-RAT) while UE is in packet switched (PS) connected state cell Dedicated Control Channel (cell-DCH).PS handover from WCDMA to WCDMA or GSM is a key feature of third generation wireless systems. The compressed mode, with variable transmission gaps and power levels, is standardized to support inter-frequency/inter-system handover. The various transmission gap patterns and parameters for compressed mode is specified by 3GPP specifications [3]. The aim of this paper is to present various possibilities of compressed mode patterns and implementation of compressed mode in 3G supported smart phones. This paper also presents how compressed mode helps to achieve uninterrupted high speed data communication in UMTS.