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Basic of GSM Um,Abis and A Interface

Basic of GSM Um,Abis and A Interface GSM (Um) Air Interface This is the interface between the GSM mobile station and the GSM Base station. The Air interface (RF Interface) uses the Time Division Multiple Access (TDMA) technique to transmit and receive traffic and signaling information between the GSM BTS and GSM Mobile Station. The … Read more

Forward Power Control in CDMA

Message Transmission Mode MS measures the frame quality and informs the base station to the result i.e. whether it is in the threshold or periodical  mode. Base station determines whether  to change the forward transmitting power or not. In IS-95 system, the forward power control is slow but in CDMA2000 system it is fast. Forward … Read more

What is Work of Paging Channel in CDMA?

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

Handoff Candidate Classification in CDMA

The mobile station continuously searches for Pilots to detect the presence of other CDMA signals that have the same carrier frequency and measures the strength (received Ec/Nt) of the pilots.  When the mobile station detects a Pilot of sufficient strength that is not associated with the serving cell/sector, it sends a message to the serving … Read more

LTE Frame Structure and Resource Block Architecture

LTE Frame Structure The figure below shows the LTE frame structure under Time division mode (TDD) Type 2 and Frequency Division mode (FDD) Type 1. Differences in LTE Frame Structure Main differences in LTE Frame Structure between the two modes are Frame 0 and frame 5 (always downlink in TDD) Frame 1 and frame 6 … Read more

How Modulation-QPSK in CDMA ?

     In an actual application, the system implements the modulation in this way:  as shown above, I and Q channel sequences in the figure represent two channels of cyclic PN short code sequences.  The cyclic period of each channel of PN short codes is 215. For different sectors, there are different starting locations of I … Read more

Ranging in Wimax

The initial range is the process of estimating the distance or propagation time between a transmitter and a receiver. Area information can be used to assist in setting operating parameters for the transmitter and receiver. Since each MS has a unique distance from the base station, it is critical in the uplink to synchronize the … Read more

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 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

What is inside SIM Card (Subscriber Identity Module) ?

Subscriber Identity Module (SIM) The SIM as mentioned previously is a “smart card” which plugs into the ME and contains information about the MS subscriber hence the name Subscriber Identity Module. The SIM contains several pieces of information: International Mobile Subscriber Identity (IMSI)This number identifies the MS subscriber. It is only transmitted over the air … Read more

How To Set Pilot Search Window Sizes in CDMA ?

When the handset first powers up, it does an exhaustive search for the best pilot. No windows are used in this process. On the paging channel, the handset learns the window sizes SRCH_WIN_A, N, R and uses them when looking for neighbors both in idle mode and during calls. When a strong neighbor is requested … Read more