Ultra Wide Band radio technology is a known to those skilled in the art. Many definitions exist for UWB technology. For example, UWB technology differs from conventional narrow band radio and spread-spectrum technologies in that the bandwidth of the signal at −10 dB is typically greater that 20% of the center frequency, or at least 500 MHz wide.
Until now, existing Ultra Wide Band approaches with a Pulse Position Modulation do not treat ISI. Indeed, symbol times are chosen wide enough so as to minimize ISI. Thus, systems developed by companies like Xtreme Spectrum with the standard IEEE 802.15 or the European search group UCAN have restricted bit rate to take into account this constraint. With this approach, the transmission can be performed without regard to the ISI.
To consider higher bit rate, known approaches comprise algorithms to process ISI, only using hard input/output. For example such approaches comprise classic equalizers like a Decision Feedback Equalizer or a Minimum Mean Squared Error. But those approaches do not completely cancel ISI. In the article “Coding an Equalization for PPM on wireless infrared Channel” by Lee,. D. C. M; Kahn, J. M; Communications, IEEE Transactions on, Volume 47 Issue 2, Feb. 1999, Pages 255-260, an approach with a trellis coded modulation is presented. In this case, the dependency between the modulation (number of PPM) and the coding removes the flexibility from the system.
In the article “Performances of an indoor optical wireless PPM-CDMA system with interferences cancellation schemes” Sung Soo Hwang, Chanbum Park, Jae Hong Lee, Personal, Indoor and Mobile Radio Communications, 1997, “Waves of the Year 2000” PIMRC 1997, The 8th IEEE International Symposium on, Volume 3, Sep. 1-4 1997, Pages 974-978, a system for canceling interferences between several users (“Multiple Access Interferences” using a SIC (“Subtract Interference Cancellation”) is presented for a modulation “on-off keying” for optical systems; so the context of this algorithm is very specific.
USPTO Backgrounds
USPTO Backgrounds