Optimal power allocation under an uncertain noise floor for Gaussian interference channels | |
| Author | Guruacharya, Sudarshan |
| Call Number | AIT Thesis no.TC-09-06 |
| Subject(s) | Radio--Transmitter and transmission--Fading Random noise theory |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Telecommunications, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. TC-09-06 |
| Abstract | This thesis considers the problem of transmitter power allocation when channel state information (CSI) is present only at the receiver for multi channel, multi user communication. when CSI is perfectly known at both the transmitter and receiver, it is known that the optimal power allocation policy is given by waterfilling procedure in both the frequency and time. But the capacity improvement due to such adaptive scheme with CSI at transmitter is found to be negligible when compared to non-adaptive scheme, when CSI is unknown to the transmitter. Since adaptive power allocation policies require complex system design, we examine the more simple alternative. In this thesis, we examine the power allocation from the perspective of interference noise power, instead of the usual channel gain. We derive the necessary and sufficient conditions for optimal power allocation policy under noise power uncertainty for a single user, and express it in terms of Hilbert transformation. An algorithm is developed, based on this condition, to allocate the transmit power optimally. We show the power allocation policy when the noise power is perfectly known and completely unknown. We also obtain the condition for the maxi-min achievable data rate. We then examine the consequence of such a policy in multi user power allocation problem, when Gaussian interference channel is considered, using non-cooperative game theory. We show the existence of a unique and pure Nash equilibrium. An iterative algorithm is given to attain this Nash equilibrium in a distributive manner. Lastly, Monte Carlo simulations done in MATLAB are presented to compare the performance of various power allocation methods for a single user with unknown direct link gain. For given SNR, the waterfilling method with CSI at receiver and transmitter yielded the largest average capacity out of all the power allocation scheme. Whereas for CSI only at receiver, capacity achieved by optimal power allocation was higher than uniform power allocation. Lastly, the capacity achieved by maxi-min policy is the lowest of them all. Simulation results for multiuser power allocation is also given for a system with two and three users competing for two subchannels. Although an analytical verification of convergence of the iterative power allocation could not be performed, the simulations show that algorithm does converge. |
| Year | 2009 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. TC-09-06 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Telecommunications (TC) |
| Chairperson(s) | Rajatheva, R. M. A. P. |
| Examination Committee(s) | Poompat Saengudomlert;Erke, Tapio J. |
| Scholarship Donor(s) | Findland Government;AIT Fellowship |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2009 |