Matched Filter Based Spectrum Sensing Technique for 4G Cellular Network

Modern and fast developments of wireless technologies have directed to a great demand for resources. It can be seen in the study that the range of existing spectrum is not used effectively, therefore the frequency band should be observed to ensure proper usage and to have the information of primary or licensed user is very much essential. In this research work uplink of LTE (Long-Term Evolution) is observed through MF (Matched Filter) spectrum sensing technique of CR (Cognitive Radio) network. This method examines the existence of signals in minimum possible time, reduces the hindrances between secondary users, increases accurateness of sensing and provides finest choice of threshold. In Uplink the System model which is used is known as SC-FDMA (Single Carrier Frequency Division Multiple Access). Entire simulation/results are prepared in MATLAB environment. This study also provides graphical contrast of simulated and theoretical results of matched filter and energy detection technique.

This result in a new structure is known as CR, which is commenced to accommodate to many consumers with high rates of data. This is regarded as the best way out for this type of problem. The intellect layer in sensing of spectrum is indicated in a CR that has the purpose of controlling spectrum frequency band. The sensing spectrum layer performs two key tasks; first find the band and decide which portion is empty (white spaces) also findout the occurrence of licensed consumer; second, the CR decides that the free spectrum will be assigned to unauthorized users without the intervention of licensed users [2].
LTE is required to be more flexible because of the utilization of the bandwidth and is expected to give high information rates and latencies at the edges of the cell. Therefore, the system of transmission for mobile station to base station (uplink) and base station to mobile station (downlink) is required to be equipped for new results superior to 3G networks [4].

NON-COOPERATIVE DETECTION TECHNIQUES
The recognition of primary user signal is essentially based on non-cooperative detection. The best known noncooperative detection techniques used for spectrum sensing are: energy detection, cyclo stationary, wavelength and matched filter [2].
Currently, the practice which is famous for detection has been an energy detection technique but the main problem of this procedure is that with a low SNR (Signal-to-Noise Ratio), this provides regrettable performance, while in noise licensed consumers have no adequate dissimilarity among them. While SNR is increased with the method of MF; it also requires a minimum time to obtain high amount of processing gain.

MATCHED FILTER SPECTRUM SENSING
A linear filter is also identified as MF which needs less time for detection and is considered as good noise detector. On behalf of a known input signal, the filter has been designed to extend the SNR output. For this reason, matching filter needs information about the shape of pulse, bandwidth and modulation and format of frame etc. [7]. The MF spectrum acquisition needs a priori PU (Primary User) information to accommodate a secondary consumer. In association with further detection practices, MF has the utmost SNR of the received signal.
Its process is identical as that of correlation; using filter, an unknown signal is convolved. Its desire reaction must be repeated and changed over time through the position signal.The Equation (1)

SYSTEM MODEL
In the Uplink portion of LTE physical layer, a SC-FDMA is selected as fundamental scheme of multiple access.
Many of the useful blocks of OFDMA are reused, so they are considered as a scheme of multicarrier.

Transmitter
Transmitter converts input binary data in to a set of  [11] equalization can be performed to acquire relief from distortion of the medium.

Channel
To provide simulation in communication system, it is important to have an enhanced channel quality of a model for sending reliable data between transmitter and receiver.
the requirements like nonstop propagation fading and multiple routes are important because that requires time variant medium that is difficult to be accurate as it occupies continuous assessment. Primarily fading is the consequence of multi path transmission. This leads to an amount of aspects as scattering, diffraction and reflection [12]. Multi path causes can be considered as constructive and destructive interference which lead to phase change and frequency change. It is possible to have direct connection with LOS (Line-of-Sight) but in reality it is not reliable because it is not measured as a good estimate.

Rayleigh Distributions
Rayleigh distribution is used to illustrate the effect of

Receiver
Receiver receives a low-frequency signal during demodulation. Signal can be converted back in to a digital form by performing digital processing which eradicate the CP. Subsequently the elimination of CP information would be renewed in to parallel. After the conversion, the receiver changes the received frequency in the frequency domain using the DFT blocks; subcarriers are subsequently demapped [12]. Next to that, frequency domain equalization is performed. In addition,the compensation for the frequency ratio equalizer is estimated using the MMSE (Minimum Mean Square Error), which is the most commonly available equalizer [12]. The use of IDFT equalizer signal is renovated in reformatted time domain which is again renovated in data of serial mode, finally in time domain detection is performed.