| Optimization Framework and Graph-Based Approach for Relay-Assisted Bidirectional OFDMA Cellular Networks Recent countries visiting this post |  |
 | 7 | United States |
 | 4 | |
 | 1 | China |
 | 1 | Sweden |
 | 1 | Russian Federation |
| Optimization Framework and Graph-Based Approach for Relay-Assisted Bidirectional OFDMA Cellular Networks Recent countries visiting this post | |
| 7 | United States |
| 4 | |
| 1 | China |
| 1 | Sweden |
| 1 | Russian Federation |