1. Dr. Ahmed El-MahdySpread Spectrum Communications (1) Performance of LTE uplink over frequency selective fading channel in impulsive noise environment (2) Performance of LTE downlink over frequency selective fading channel in impulsive noise environment. (3) Performance of LTE uplink in impulsive noise environment and non-fading channel. (4) Performance of LTE downlink in impulsive noise environment and non-fading channel (5) Channel estimation of OFDM system Projects

2. Dr. Ahmed El-MahdySpread Spectrum Communications LTE (4G)

3. Dr. Ahmed El-MahdySpread Spectrum Communications Long Term Evolution (LTE) LTE commonly marketed as 4G LTE. It is a standard for wireless communication of high-speed data for mobile phones. The main requirements for the new access network are high spectral efficiency, high peak data rates, short round trip time as well as flexibility in frequency and bandwidth. In LTE, both Frequency-division duplex (FDD) and time-division duplex (TDD) transmission are supported.

4. Dr. Ahmed El-MahdySpread Spectrum Communications Long Term Evolution (LTE) Orthogonal Frequency Division Multiple Access (OFDMA) is considered the most appropriate scheme for achieving high spectral efficiency for the LTE downlink. Since, OFDMA suffers from power distortion that may be particularly troublesome in uplink transmissions where excessive complexity in user terminal is an issue. Therefore, for the uplink, the LTE employs SC-FDMA due to its low PAPR properties compared to OFDMA. These multiple access solutions provide orthogonality between the users, reducing the interference and improving the network capacity.

5. Dr. Ahmed El-MahdySpread Spectrum Communications Long Term Evolution (LTE) Figure 2

6. Dr. Ahmed El-MahdySpread Spectrum Communications Downlink: OFDMA Figure 3. OFDMA system model for downlink.

7. Dr. Ahmed El-MahdySpread Spectrum Communications Problems of OFDMA (1)Peak to average power ratio. When the independently modulated subcarriers are added coherently, the instantaneous power will be more than the average power. Fig. High peaks in OFDM signal generated by summing multiple sinusoids

8. Dr. Ahmed El-MahdySpread Spectrum Communications Problems of OFDMA Such high peaks will produce signal that goes into nonlinear region of operation of the power amplifier (PA) at the transmitter, thereby leading to nonlinear distortions and spectral spreading. High peak-to-average-power ratio (PAPR), requiring linear transmitter circuitry, which suffers from poor power efficiency.

9. Dr. Ahmed El-MahdySpread Spectrum Communications Problems of OFDMA (2) Carrier frequency offset. The ability of OFDMA systems to achieve higher data rates and facilitate bandwidth friendly communication is impaired by the necessity of accurate frequency synchronization between the receiver and the transmitter. With frequency deviation, the sub-carriers will no longer be orthogonal causing inter-carrier interference.

10. Dr. Ahmed El-MahdySpread Spectrum Communications UpLink: SC-FDMA System Figure 4. SC-FDMA system Model for UPlink

11. Class-A Impulsive Noise

12. Dr. Ahmed El-MahdySpread Spectrum Communications Class-A Impulsive Noise  Sources for man-made noise are e.g. radio frequency emissions from all sorts of electronic devices used in all daily life, automotive ignition noise, and power transmission line.  The white Gaussian noise component is presented in the class-A noise model to describe the influence of thermal noise which is naturally present in the real physical receiver.  The impulsive noise is defined by two parameters which are the impulsive index A and the Gaussian factor Γ. As A decreases the noise becomes more impulsive. On the other hand, As A increases the noise becomes more Gaussian. 12

13. Dr. Ahmed El-MahdySpread Spectrum Communications Class-A Impulsive Noise 13  For A=0.1:  For A=0.01:

14. Dr. Ahmed El-MahdySpread Spectrum Communications Class-A Impulsive Noise 14 The class-A impulsive noise has a probability density function (pdf): Where:  A is called the impulsive index of noise.  is given by : Where: is the mean variance of class A impulsive noise. Г is the ratio of the mean power of the Gaussian noise component to the non- Gaussian impulsive noise component.

15. Dr. Ahmed El-MahdySpread Spectrum Communications Impulsive Noise PDF 15  The impulsive noise PDF is only considered for m=0,1,2.

16. Dr. Ahmed El-MahdySpread Spectrum Communications (6) Resource allocation for device to device communications Projects

17. Dr. Ahmed El-MahdySpread Spectrum Communications 5G: versus Conventional Cellular Networks

18. Dr. Ahmed El-MahdySpread Spectrum Communications Device to Device Communications

19. Dr. Ahmed El-MahdySpread Spectrum Communications Resource Allocation Algorithms

20. Dr. Ahmed El-MahdySpread Spectrum Communications Device to Device Communications

21. Dr. Ahmed El-MahdySpread Spectrum Communications Projects (7) Multi-Source cooperative communication with interference cancellation in amplify and forward protocol (8) Multi-Source cooperative communication with interference cancellation in decode and forward protocol (9) Incremental Hop selection scheme for amplify and forward relaying (10) Incremental Hop selection scheme for decode and forward relaying

22. Dr. Ahmed El-MahdySpread Spectrum Communications Cooperative Communication with Relays

23. Dr. Ahmed El-MahdySpread Spectrum Communications Cooperative Communication with Relays

24. Dr. Ahmed El-MahdySpread Spectrum Communications

25. Dr. Ahmed El-MahdySpread Spectrum Communications Relay Transmission Strategies Decode and Forward Amplify and Forward Compress and forward Most popular are: Decode and Forward (DF) and Amplify and Forward (AF)

26. Dr. Ahmed El-MahdySpread Spectrum Communications Decode and Forward (DF) During the first interval, the transmitter sends the signal to the relay: The relay decode and re-encode the received signal and during the second interval it forwards it to the destination:

27. Dr. Ahmed El-MahdySpread Spectrum Communications Amplify and Forward (AF) During the first interval, the transmitter sends the signal to the relay: relay multiplies its received signal by a coefficient (Gain) and during the second interval it forwards it to the destination.

28. Dr. Ahmed El-MahdySpread Spectrum Communications Multi-Source cooperative communication with interference cancellation

29. Dr. Ahmed El-MahdySpread Spectrum Communications Incremental Hop selection scheme

30. Dr. Ahmed El-MahdySpread Spectrum Communications Cooperative Communication with Relays