How QPSK & BPSK Modulation in WCDMA?
A data-modulation scheme defines how the data bits are mixed with the carrier signal, which is always a sine wave. There are three basic ways to modulate a carrier signal…
Location Area Identity (LAI) and Global Cell Identity (GCI) in CDMA
Location Area Identity (LAI) PAGING message is broadcast within a local area, the size of which depends on traffic, paging bearer capability, signaling flow , etc. Format: MCC+MNC+LAC MCC: Mobile…
Transmit Diversity & Receive Diversity
Transmit Diversity MISO = Multiple Input Single Output Principle More complex than SISO. 2 or more transmitters and one receiver. MISO is more commonly referred to as transmit diversity. The…
How to Reverse Access Channel Work in CDMA?
Reverse Access Channel used by MS Initiate Communication or Respond to Paging Channel. A reverse channel is first spread with WALSH to 307.2Kbps and then becomes 1.2288Mcps after long code…
WCDMA Channelization Code
OVSF Code (Orthogonal Variable Spreading Factor) is used as channelization code Orthogonal codes are easily generated by starting with a seed of 1, repeating the 1 horizontally and vertically, and…
Forward Traffic Channel of CDMA
Forward Traffic Channel is used to Transmit Data and Signaling Information. Symbol repetition makes symbol streams at different rates adapted to those at the rate of 19.2k. The original symbol…
How Common Control Channel (CCCH) works in GSM ?
RACH(Random Access Channel) Uplink only. Used by the MS when making its first access to the Network. The reason for access could be initiation of a call or a page…
What is Work of Paging Channel in CDMA?
The paging channel transmits: System parameters message Access parameters Neighbors list CDMA channels list message The paging channel accomplishes: Paging to MS Assign traffic channel to MS The frame length…
How Sync Channel work in CDMA?
A long code is used for scrambling. However, a long code has too long a period, which cannot be wholly used for scrambling. We can only sample some chips of…
What is Basic work of Pilot Channel in CDMA?
A pilot channel: Assist mobile station to be connected with CDMA network Handles multi-path searching Provide the phase reference for coherent demodulation and help the mobile station estimate the transmission…
Transmit Diversity of CDMA
Diversity technology means that after receiving two or more input signals with mutually uncorrelated fading at the same time, the system demodulates these signals and adds them up. Thus, the…
What is T_ADD,T_DROP and T_TDROP in CDMA?
Pilot Detection Threshold (T_ADD) Any Pilot that is strong but is not in the Handoff Direction Message is a source of interference. This Pilot should be immediately moved into the…