BIT ERROR RATE ANALYSIS IN DIFFERENT TERRAINS FOR LTE

Focus of this paper is mainly evaluating the performance of Long Term Evolution (LTE) system in different terrains such as urban, suburban and rural area. The performance parameters such as, Bit Error Rate (BER) and the Data Throughput are reported in terms of Signal to Noise Ratio (SNR). The system parameters taken into consideration are signal to noise ratio (SNR), number of receiving antenna (RxAn), reference channel and duplex mode. All of the simulations were performed in MATLAB, version 2014a simulink. The results are presented in table and graph which gives clear idea of the effect of environment on signal and receiver sensitivity. Also bit-error-rate, an important parameter in case of receiving signal, is analyzed with respect to SNR values. A comparative analysis of bit-error-rate is performed between three areas for same conditions which proves that LTE signal is well suited in a rural area than that of a suburban and urban area.


Introduction
Long Term Evolution (LTE), the fourth generation of mobile technology, is a wonder for mobile communication. LTE delivers high speed transfer rates (up to 300Mbit per second), downloads the files faster, provides increased capacity, experiences low power consumption and smooth handover. Spectral efficiency, flexible bandwidth usage and cell breathing phenomena of LTE ensure reliable and enriched mobile communication. All IP network architecture, packet switched operations, use of MIMO antenna technology, use of SC-FDMA and OFDMA in uplink and downlink respectively, effective channel resource utilization, low handover latency features of LTE proves itself superior than other mobile technology. It supports data as well voice [1,2].
In the race of high speed for mobile subscriber, LTE offers fastest speed than other 4g wireless communication. Long Term Evolution (LTE) is the latest high speed 4G technology introduced in 2010 by AT & This standard is developed by 3GPP and is specified in its release 8 series. LTE is the best technology from 1G, 2G and 3G. First generation (1G) introduced in 1980 was based on  One of the magic stick behind the high speed and quality data and signal transmission by LTE is the reduced possibility of error launched in the medium. During the transmission of data over a data link, there is every possibility of being corrupted by errors introduced into the system. In consequence, the integrity of the system may be compromised. To maintain the quality of the signal, it is necessary to assess the performance of the system, and bit into the system. In consequence, the integrity of the system may be compromised. To maintain the quality of the signal, it is necessary to assess the performance of the system, and bit error rate (BER), provides an ideal way in which this can be achieved. BER is defined as the rate at which errors occur in a transmission system. It is the number of bit errors per unit time. The bit error ratio is the number of bit errors divided by the total number of transferred bits during a prescribed time interval. This key parameter is used to 1) Assess systems that transmit digital data from one location to another.
2) Assess the full end to end performance of a system including the transmitter, receiver and the in between medium. 3) Help in enabling the actual performance of a system in operation.
For better medium between the transmitter and receiver, the signal to noise ratio is high, then the bit error rate will be very small and insignificant [4]. On the other hand, in presence of noise, the bit error rate will need to be considered. In this paper, bit error rate analysis is performed for LTE 4G network in urban, suburban and rural area by simulation MATLAB simulink. In this paper section II highlights some related works done previously very much linked with this work, their considerations and their observed inferences. Section III, IV and V mention the system model, mathematical model and system set up. Various simulation criteria are described in section VI. Section VI also analyzes the results and comparative study of BER for three different areas.

Related Works
This section discusses about the recent research techniques that were published in different reputed journals. Elfatihi et al. [5]

System Model
The system model is composed of a transmitter, a channel model, and a receiver shown in figure  1.
The processing chain in the transmitter is specified in detail by the standard. The standard also specifies various channel models for performance evaluations. The receiver operation provides the opportunity for various system designers to distinguish their implementation with distinct performance profiles.

Mathematical Expression
The This equation implies that the SNR will be more than Eb/N0 by a factor of Rb (if Rb > 1 bit/second).Increasing the data rate will increase the SNR, however , increasing Rb will also cause more noise and noise term also increases ( due to ISIinter symbol interference , since more bits are packed closer and sent through the channel).

System Set Up
The  Reference Channels  Duplex Mode All of the simulations were performed in MATLAB, version 2014a simulink.

Simulation Parameters
The key system parameters are tabulated below in TABLE II.

Results and Discussion
In this paper throughput and bit error analyses are performed for three different terrains such as 1) Urban area 2) Suburban area 3) Rural area

Urban Area
The following figures refer to the simulation of throughput analysis on urban areas.
Simulation of throughput analysis of LTE PDSCH on Urban area at RxAn-2 The two graphs in Fig.1. represent SNR vs. Throughput and Average Throughput per frame respectively where SNR limit is set to 0 dB to 5 dB.

Suburban Area
The following figures represent simulation of throughput analysis of LTE in suburban areas.  Figure 3 shows the throughput of LTE in the rural condition. In a rural area, there is almost no obstacle, as a result the chances of reflection of the signal is about zero. So the throughput is 100% and the received signal is almost same as the transmitting signal.
In the above figures it is found that for a particular value of SNR, goes higher, throughput increases exponentially. In other words, As SNR decreases, the throughput will decrease exponentially. After certain values of SNR, throughput becomes maximum. Highest throughput means higher quality performance without noise. Throughput analysis also gives a clear view of Bit-Error-Rate within different atmospherical condition.  Figure 4, for urban area , when SNR is minimum (0 dB), BER is maximum (0.23), again at the maximum point of SNR the BER is reduced to 0.13, giving a reduction of 0.10, yet it's very high for a good quality of signal and cause an weak signal in the receiver. For sub urban area, the lowest error rate is 0.0425 at SNR 9 dB . Here, in suburban area the signal quality is better than urban area with only two receiving antennas whereas for urban with two receiving antennas the throughput and BER were 46.67% and 0.1380 respectively at SNR 5 dB. Again in rural area condition, bit-error-rate is less than 0.005, which is theoretically equal to 0. As a result, an ideal state can be obtained from this simulation. From the above observation it is clear that, the effect of environment on signal and receiver sensitivity play an important role on transmitting signal. Bit-Error-Rate, is very lower rate in rural areas. Lower BER gives an excellent indication of the performance of a wireless system. After comparing all of the conditions, LTE signal is well suited in a rural area than that of a suburban and urban area because of the less congestion and obstacles.

Conclusion
The bit error rate and throughput analysis of LTE network for different simulator parameters have been done in terms of tables and graphs using MATLAB software against signal to noise ratio in different terrains. The result shows that bit-error-rate is very lower in rural areas than other two areas.
The signal quality of other areas can be improved by increasing the sensitivity of receiver, hence by increasing the number of receivers. Further work will focus on bit-error-rate analysis based on different modulations schemes in different terrains.