Invention:
To improve the sensing efficiency and/or the throughput for the SUs, this technology develops a new adaptation method that exploits selfinterference suppression (SIS) capabilities in an SU device. Using this adaptation method, an SU can switch between a transmission-sensing (TS) mode and transmission-reception (TR) mode.
Background:
In a DSA environment, wireless devices may be operated by primary (non-adaptive) and secondary (adaptive/cognitive) users. Secondary users (SUs) are allowed to access the spectrum opportunistically on a non-licensed basis, provided that they do not harm the transmissions of primary users (PUs). Until recently, the idea that a wireless device can transmit and receive simultaneously on the same frequency channel, i.e., operate in full-duplex (FD) mode, was deemed impossible. The traditional scenario was that at a given time, a node can transmit or receive, but not both, which is often called half-duplex (HD) operation. The problem of achieving FD communications is that the transmitted power from a given device is typically much larger than the received power of another signal that this device is trying to capture. While the device is receiving the second signal, its own transmitted signal is considered self-interference. The infeasibility of FD communications has recently been challenged in several efforts, which have successfully demonstrated the possibility of FD communications using self-interference suppression (SIS) techniques. The main novelty of these efforts is to suppress self-interference to a level that enables FD communications. A commonly accepted scheme for protecting Pus from SU transmissions is the Listen-Before-Talk (LBT). In the LBT scheme, an SU device has to periodically interrupt its transmission (e.g., once every two seconds) and senses the channel for PU activity (transmissions). To do that, SUs must sense the PU communications activity over the wireless channel, an inherent problem of which in the traditional LBT scheme is that it results in a reduction in the SU throughput.
Applications:
- This product could be implemented into a wireless network that has a series of primary users and secondary users that implements a form of dynamic spectrum access. Primary interest would be in large scale telecommunication networks.
Advantages:
This invention has been demonstrated to be superior to the state-of-the-art in (a) theory, (b) simulations, and (c) using real data from a phantom. Our simulation results show orders of magnitude in improvement, as compared to traditional methods. Real results from phantom data closely replicate the performance of our simulations.
- Proposed method does not suffer from the noise-bandwidth trade-off
- Can estimate very accurate field inhomogeneity maps over an arbitrary range of values
- Method can be optimized to the imaged material or tissue of interest
- Method does NOT require a phase unwrapping routine
Status: issued U.S. patents #10,645,589
