The common pilot channel, CPICH, is used in the transmission of the carrier responsible for estimating the channel parameters. It acts as a physical reference for the other channels in the wideband CDMA system. Some of its roles include, controlling power, ensuring transmission and coherent detection, performs channel estimates, measurement of adjacent cells and obtaining the scrambling code. Most sections are developing and building and other tall structures come up all the time. A lot of interference is experienced with regards to the telecommunication networks. In practice, when the telecommunication engineers and designer set up antennae to serve a given range. Several reports have shown that the UMTS or the commonly known, 3G coverage is more interference tolerant as compared to the GSM technology implementations . The antenna may be transmitting signals at ta very high-power level but still the communication could be affected and as a result there is reduction in transmission rate. There has been a great evolution in the mobile communication standards as defined by the third-generation partnership project, 3GPP. The wideband CDMA is an ultra-terrestrial radio access technology or standard that incorporates both the FDD and the TDD operations. The evolution is usually based on the improvement of the data transmission rates for both the uplink and the downlink.
There has been a tremendous increase in the number of subscribers locked in WCDMA over the last decade. Multiple users are able to send signals to the node B or the Base Station subsystem and the base propels different signals to diverse users. The system has different sectors such as the turbo encoder, inter-leaver or de inter-leaver, OVSF code generator, convolutional encoder, cyclic redundancy checker, and the scrambling code . The scrambling code usually make the direct sequence CDMA technique have a higher level of efficacy in a multipath environment. The code tends to reduce the auto-correlation that occurs between different time delayed versions of the spreading code. The reduction is such that the receiver can uniquely decrypt the different paths . These codes separate the users and the base station sectors from each other by allowing them to individually manage the OVSF tree . The management process is done without coordinating amongst themselves. The transmission from different sources are divided by the scrambling codes. The short and long scrambling codes are available . The rake receiver determines if the long scrambling codes are to be used in a given base station. The CPICH uses a length of 256 OVSF code such that during the channelization process, the channels are scrambled with the truncated Gold sequence as shown in the table above. The primary and secondary synchronization channels are added to the output of scrambling. The PSCH and the SSCH are not orthogonal to the other codes in the system. This channel uses the spreading factor of 256 chips per symbol and there are 10 default pilot symbols in a given channel slot. There is a distinct tradeoff in the CDMA network in terms of the coverage and capacity. The tradeoff is attributed to the limited power availability for the users.
- To detect the scrambling code and signal strength of the pilot CPICH
- To ascertain the valid channel codes and their respective signal strength
- To decrypt the traffic channels and read the enclosed message and demonstrate some open-ended investigation.
Using the LTE system toolbox in MATLAB R2017a, it was easy to generate the standard output for both the uplink and downlink complex baseband waveforms .
The scrambling code was loaded on to the system as shown in the code snippet below. Identifying the scrambled code and the strength of the final CPICH signal. The signal strength is plotted and the code is recovered from the scrambled code.
The message from the scrambled code is then recovered as shown in the snippet below. The message was decoded by introducing the AWGN noise as used to recover the message.
In a nutshell, the paper has sufficiently covered the scrambled codes and their utilization in the pilot channels. It is prudent to conclude that the efficient planning and optimization of mobile networks is paramount in guaranteeing the superior quality of service and user experience . The network operation requires the CDMA network to utilize the scrambling code for the short and long codes in order to enhance optimization. The CDMA networks have operators that can quickly and efficiently utilize their network resources to achieve optimum system capacity. The interference level affects the capacity and the coverage of the cell. Further reduction of the interference results in better communication and transmission rates.
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