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 in a digital sense: amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK). In ASK the amplitude of the carrier signal … Read more
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 Country Code, 3 digits. MNC: Mobile Network Code, 2 digits. LAC: Location Area Code, a 2-byte-long hexadecimal BCD code. 0000 cannot be used with FFFE. … Read more
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 same data is sent on both transmitting antennas but coded in such a way that the receiver can identify each transmitter. Benefits Transmit diversity increases … Read more
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 modulation. The long code here not only spreads spectrum, but implements the function of channelization. “Data burst randomizer” means discarding repeated chips during the transmission … Read more
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 then complementing the -1 diagonally. This process is to be continued with the newly generated block until the desired codes with the proper length are … Read more
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 stream at the rate of 19.2Kbps will not be repeated, 9.6Kbps symbol stream will be repeated once, 4.8Kbps symbol stream will be repeated twice…. Then, … Read more
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 response. AGCH (Access Grant Channel) Downlink only. Used for acknowledgement of the access attempt sent on RACH. Used by the network to assign a signaling … Read more
What is Work of Paging Channel in CDMA?The Paging Channel in CDMA (Code Division Multiple Access) serves a crucial role in the efficient functioning of the communication system. As a dedicated control channel, the Paging Channel is responsible for transmitting important information, such as incoming calls and system messages, to mobile devices within a CDMA … Read more
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 a long code at some point of time and use them as the sequences of scrambling. This requires that a mobile station should know the following … Read more
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 power The mobile station measures and compares the pilot channel powers from the base stations during the handoff Forward pilot channel is spread over W0 … Read more