WCDMA vs. HSDPA Network Technology

Difference Between WCDMA and HSDPA Network Technology

WCDMA (Wideband CDMA)

While it is mostly used in the 3G mobile networks radio access interface, WCDMA is the multiple access technology that allows the 3G users to get more secured communication with much higher data rates. The purpose of broadband communication is to give the users higher data rates so that they can have high speed internet, mobile gaming, video streaming and conferencing facility through the mobile terminal. WCDMA originated as a part of 3GPP so that a global interoperability among 3G networks can be achieved.

The WCDMA working technique is that the 5MHz channel bandwidth is utilized to send the data signals on air interface and to unsure this happens the original signal is mixed with a random pseudo noise code also called Direct Sequence CDMA which is a unique code for each user. Only the users with the correct code can decode the message. So due to the high frequency that comes along with the pseudo signal, the original signal is modulated in to higher bandwidth and because of the high spectrum, the  spectral components of the original signals sink in the noise. Thus jammers detect the signal as a noise without the pseudo code.

WCDMA utilizes the TDD or the FDD mode in order to get total duplex communication. In TDD mode both the uplink data and the downlink data are transferred over a single 5MHz channel along with time multiplexing. However FDD mode utilizes two separate uplink and downlink channels. These channels are separated by 190MHz band. WCDMA in fact uses QPSK as the modulation scheme. WCDMA supports 384kbps and over 2Mbps in mobile and static environments respectively (as mentioned by ITU for 3G networks) while in case of voice calls data rates can carry up to 2Mbps data speeds.

HSDPA (High Speed Downlink Packet Access) is the next level of 3G UMTS that is used to get data speeds for data oriented applications where you can get increased downlink data rates no matter what the rate of uplink is. Using this technology the network capacity can be improved and costs per bit transmission also can be lowered.

As far as the data rates are concerned the proposed networks can deliver a maximum of 14.4 Mbps downlink with the higher order modulation schemes over the 5MHz channel band width of the WCDMA. HSDPA will use 16 QAM (Quadrature Amplitude Modulation) as the digital modulation scheme which increases the data rates up to 14.4 Mbps and has an added advantage of which makes the signal noise resistant. HSDPA mobile terminals have 12 categories by 3GPP which defines the different data rates in HSDPA. These rates are dependant on factors like TTI, Transport Block Size, modulation schemes etc.


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