Abstract
In cognitive radio systems, secondary users may transmit signals by aligning their signal directions to the primary user's unused directions. However, their achievable transmission rates are very low in moderate to high SNR regime because the primary user takes most of available degrees of freedom (DoF). In order to increase the secondary transmission rate, we consider the case that the primary receiver performs interference suppression filtering. By counting the number of variables and the number of equations in the interference alignment (IA) condition, we analyze the secondary users' achievable DoF, which is higher than the conventional scheme. Simulation results show that the primary receiver's participation in IA significantly increases the secondary rate with negligible primary rate reduction.
| Original language | English |
|---|---|
| Article number | 6203468 |
| Pages (from-to) | 1072-1075 |
| Number of pages | 4 |
| Journal | IEEE Communications Letters |
| Volume | 16 |
| Issue number | 7 |
| DOIs | |
| State | Published - 2012 |
Bibliographical note
Funding Information:Manuscript received April 1, 2012. The associate editor coordinating the review of this letter and approving it for publication was J. Choi. The authors are with the School of Information and Communication Engineering, Inha University, Incheon, Korea (e-mail: [email protected]). This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (No. 2010-0003603). This work was also supported by INHA University. Digital Object Identifier 10.1109/LCOMM.2012.051512.120719
Keywords
- Interference alignment
- cognitive radio
- cooperative primary receiver
- degrees of freedom