SBIR-STTR Award

We propose the Flexceiver, an ultra-wideband, spread spectrum modem for long range wireless networks. The basic concept of the Flexceiver is to sweep the carrier frequency of a modulated signal very rapidly across a wide bandwidth. The Flexceiver avoids interfering with other RF systems operating in dedicated bands by dynamically constructing frequency profiles that hop over the frequencies occupied by those systems. RF interference from other systems is avoided in the same manner. All-weather capability is enabled by operating below the 4 GHz band where attenuation due to weather is insignificant. Low latency is afforded by the FPGA based implementation. By eliminating from the link budget a fading allowance, high data rate and range performance are facilitated by multipath tolerance of the system. While the total occupied bandwidth is wide, the instantaneous bandwidth of the waveform is narrow, consistent with that of the rate and type of modulation. The channel fades that occur at specific frequencies can be very deep, but are narrow and low duty cycle compared to the total occupied bandwidth. By sweeping rapidly, individual fades can be limited to single bit duration or less. Forward error correction is employed to recover faded bits. The anticipated benefit of developing a Flexceiver, a flexible Software Defined Radio (SDR) transceiver, targeted for long range wireless networks include: all-weather capability, ElectroMagnetic Compatability (EMC) with other RF devices, resistance to ElectroMagnetic Interference (EMI), Low Probability of Detection (LPD), and Low Probability of Jamming (LPJ).

The Flexible Transceiver (Flexceiver) is a Software Defined Radio (SDR) that can be configured to transmit and receive any variety of communications waveforms. For instance, it could be configured to implement the CDMA cellular phone waveform while in the USA and then be reconfigured to implement the GSM cellular phone waveform when in Europe. Multipath immunity is among the advantages of Flexceiver technology. Multipath is the name given to the phenomenon that causes cell phone and radio station fades. For instance, while sitting at a traffic light you may loose the radio station you were listening to (due to a fade) and then recover reception by drifting six inches forward. The Flexceiver supports waveforms that eradicate this phenomenon, dramatically improving one-way and two-way RF communications systems. The Flexceiver features the capacity for the opportunistic use of radio frequency spectrum is an attribute that will become increasingly important as our frequency bands become more crowded. The ranging capability of the Flexceiver can be leveraged for positioning applications such as location of children and parents within an amusement park, tracking of busses and taxi cabs, and warehouse inventory management. The high accuracy consensus clock feature facilitates low power networking by enabling all network devices to go into and come out of a low power sleep mode synchronously. Low Probability of Jamming (LPJ) waveforms are particularly attractive to military markets. Low Probability of Detection (LPD) waveforms are desirable to the intelligence community.

Keywords:
LOW PROBABILITY OF JAMMING (LPJ), WIRELESS, LOW PROBABILITY OF DETECTION (LPD), SOFTWARE DEFINED RADIO, CONFIGURABLE, FADE-TOLERANT, ULTRA WIDE BAND