cdma technology optimization
Multi-path combination in the BSC during soft handoffMulti-path combination in the BTS during softer handoffs Soft handoff means that during the handoff of a mobile station at the coverage edge areas of two or multiple base stations, the mobile station receives the signals from multiple base stations (two in most cases) at the same … Read more
Two points are important here: Maximum number of shift register (N) Mask The period of out put sequence is 2N-1 bits Only sequence offset is change when the mask is changed PN stands for Pseudorandom Noise sequence In CDMA system, user information is encrypted by means of scrambling. The scramble code used here is … Read more
Deutsche Telekom is reported to have renewed discussions with the USA based regional network, MetroPCS regarding a possible merger with its own T-Mobile USA network. The two companies were last reported to be in talks back in late 2009. Citing two unnamed people familiar with the talks, Deutsche Telekom has been considering a stock-swap transaction and then … Read more
Spreading consists of 2 steps: Channelization operation, which transforms data symbols into chips Scrambling operation is applied to the spreading signal Spreading means increasing the bandwidth of the signal beyond the bandwidth normally required to accommodate the information. The spreading process in UTRAN consists of two separate operations: channelization and scrambling. The first operation is … Read more
A transport channel defines how and with what characteristics the information is transmitted. Inherited from the WCDMA, data on the transport channel is organized into “Transport Blocks”, TBs. A Transport block can be transmitted every TTI = 1 ms The “Transport Format”, TF, defines how the blocks can be transmitted: Transport block size, it depends … Read more
How Spreading & Dispreading in WCDMA-3G ? Traditional radio communication systems transmit data using the minimum bandwidth required to carry it as a narrowband signal. CDMA system mix their input data with a fast spreading sequence and transmit a wideband signal. The spreading sequence is independently regenerated at the receiver and mixed with the incoming … Read more
How Correlation works in WCDMA ? Correlation measures similarity between any two arbitrary signals. Identical and Orthogonal signals: Correlation is used to measure similarity of any two arbitrary signals. It is computed by multiplying the two signals and then summing (integrating) the result over a defined time windows. The two signals of figure (a) are … Read more
The following control logical channels have been defined by the 3GPP: BCCH, Broadcast Control Channel, used for the transmission of system control information. A UE needs to decode it before requesting a connection. PCCH, Paging Control Channel, is a downlink channel that transfers paging information and system information change notifications. This channel is used for … Read more
How WCDMA Interleaving ? Effect Interleaving is used to reduce the probability of consecutive bits error Longer interleaving periods have better data protection with more delay Channel coding works well against random errors, but it is quite vulnerable to bursts of errors, which are typical in mobile radio systems. The especially fast moving UE in … Read more
Effect Enhance the correlation among symbols so as to recover the signal when interference occurs Provides better error correction at receiver, but brings increment of the delay Channel Types No Coding Convolutional Coding (1/2, 1/3) Turbo Coding (1/3) UTRAN employs two FEC schemes: convolutional codes and turbo codes. The idea is to add redundancy … Read more