Understanding WCDMA
Knowing WCDMA or UMTS
W-CDMA wideband code-division multiple-access is among the major technologies that implement the 3G or third generation cellular systems. This is founded on the radio access technique suggested by the ETSI Alpha Group. The details and specifications were finalized in 1999. The implementation of W-CDMA is going to be a technical challenge due to the complexity and versatility. The sophistication of the of the systems of W-CDMA can be seen from various aspects.
These are namely the complexity of the overall system, computation complexity of the receiver and the complexity of ever single algorithm. W-CDMA link-level simulations or more than 10 times the compute intensive compared to 2G simulations. In the interface of W-CDMA, the different interface users can immediately transmit at varying information rates, with the data rates even varying in time. Networks of the UMTS are required to support every 2G service, plus new services and applications.
The Technical Details
As for the FDD technical summary, the frequency band will range from 1920 MHz up to 1980 MHz and 2110 MHz and 2170 MHz or frequency division duplex. The minimum frequency band needed is 2 x 5 MHz. The frequency re-use is 1. Carrier spacing is between 4.4 MHz and 5.2 MHz. The most number of voice channels on 2 x 5 MHz is 96 with a spreading factor of 256 UL and AMR or 7.95 Kbps and 98 with a spreading factor of 128 UL and AMR of 12.2 Kbps.
Other Specs
The voice coding includes AMR codecs ranging from 4.75 kHz up to 12.2 kHz, GSM EFR is at 12.2 kHz. SID is also included at 1.8 kHz. The channel coding includes convolutional coding with turbo code for high rate data. The duplexer required is 190 MHz separation with asymmetric connection supported. Tx and Rx isolation is MS:55db and BS:80dB. The Receiver is Rake, while receiver sensitivity is Node B.
More Information
Data type for the device is packet and circuit switch. Modulation is QPSK and pulse shaping is root raised cosine, rolling off at 0.22. The chip rate is 3.84 Mcps while the channel raster is 200 kHz. Maximum user data rate on the physical channel is 2.3 Mbps with a spreading factor of 4, and parallel codes of 3 DL / 6 UL, with limited interference. HSPDA will provide data speeds going as fast as 8 to 10 Mps and 20 Mbps for MIMO systems. The channel it rate is 5.67 Mbps with a frame length of 10 ms or 38400 chips.
There are 15 slots or frames, and 2560 chips. Handovers are soft and softer, plus a hard interfrequency. The power control period has a time slot with a rate of 1500 Hz. Power control step size is 0.5, 1, 1.5 and 2 dB while power control range is UL 80 dB and DL at 30 dB.
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Understanding WCDMA
Development From 2G To 3G
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UMTS And 3G
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