Underlay Control Channel Design

Although there are several techniques for detecting the start of a OFDM frame (timing synchronization) and to estimate frequency offset, they are not directly applicable to NC-OFDM due to concurrent nature of transmissions. We therefore propose a low data rate CDMA-like underlay control channel to address the above two issues. Such a control channel is envisioned to be low power and to span all available bandwidth. Multiple point-to-point links access this control channel by using different spreading codes. A two stage timing and frequency offset estimation technique is proposed using this channel. Once synchronization is established, channel is used to transmit control information such as sharing the active sub-carrier indices. For such a control channel we study the accuracy of timing synchronization, data rates achieved in control channel and effect on the performance of NC-OFDM-based data transmission.

Here is the Github code for this project:
https://github.com/r4tn3sh/ncofdm-sync-test

Here is the publication from this study

R. Kumbhkar, G. Sridharan, N. B. Mandayam, I. Seskar and S. Kompella, “Design and implementation of an underlay control channel for NC-OFDM-based networks,” 2016 Annual Conference on Information Science and Systems (CISS), Princeton, NJ, USA, 2016, pp. 228-233, doi: 10.1109/CISS.2016.7460506.

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