White papers


SigNexT Technology at a Glance

SigNexT's products and solutions are based on state-o- the-art technology and proporietary patents. At present, the primary technologies include:

Joint Constellation Multiple Access (JCMA)

Superposition modulation is used to create a composite joint symbol at the receiver, which comprises of arbitrary local constellations on power-limited transmitters. This results in a channel overloading method which makes use of joint signal constellations. It has been shown that as the number of transmitters increases, the decoding gain and the transmission security power increase too. The decoding gain may be traded for a decrease in the emitted power of the transmitters. The means for generating robust joint constellations are illustrated and demonstrated, as well as computationally-efficient detection rules with maximum likelihood. The impact of unit failure, synchronization, mobility and channel estimation errors are evaluated, and piloting rules are derived to support JCMA at the presence of such imperfections. JCMA was shown to be a feasible, efficient way for increasing the capabilities of limited power transmitters in a multiple access scenario.

Key features of JCMA:

  • Increased spectral efficiency (capacity) for limited power transmitters.
  • Support of network optimization scenarios such as the near-far problem and QoS.
  • Increased communication range (cell size in cellular telephony).
  • Secured communication against eavesdropping with no additional overhead (computational power, memory, throughput, energy).

See the JCMA white paper for more details.

Space Diversity Multiple Access (SDMA)

The SDMA technology is a breakthrough in the utilization of existing RF bandwidths, as it enables reception at the same time and at the same frequency of several uncorrelated transmission sources.
For example, a system which uses three transmission sources – each at a 20MHz bandwidth – can reduce utilization from 60MHz to about 20MHz (!).
Another benefit which the SD technology provides the communication market is an inherent capability for greatly improved system immunity against jammers (hostile or friendly/accidental), while prioritizing the received systems. For example: a cellular cell collapses when the number of users exceeds its capacity. Integrated SD technology enables the cell to ignore the additional users and avoid cell collapse while providing the cellular services to pre-prioritized users.
Another example applies to systems designed to be immune against jammers by using spread-spectrum technology. With SD, it is possible to achieve the same immunity while utilizing a narrower bandwidth. Typically, in order to achieve immunity of 30dB, the spread-spectrum technology requires a bandwidth of 15MHz. An SD implementation on the other hand will require only 1.5MHz.
The third contribution of the SD technology is Beam-Forming transmission, which allows dynamic control by the user (or the system application) of thle beam-direction and beam-width.
These capabilities cover the entire range of issues which undermine modern commercial and military communication:

  • Immunity improvement in mission critical systems, while maximizing the number of operating sub-systems in the same area, without mutual interference and interruption.
  • Utilizing more demanding, bandwidth-intensive systems in the same predefined bandwidth slots.
  • Eliminating the usage of mechanical tracking antenna systems, required for beam aiming toward or from moving systems (ground or airborne).
  • Obtaining a precise direction for the transmitting beam (according to the receiving beam) – especially in non-line-of-sight (NLOS) conditions.

With these new and unique capabilities, the SD technology improves two essential aspects which are critical for any communication system: by increasing the Signal to Noise Ratio (SNR) and enhancing focusing (beam forming) of the radiated energy to specific locations, the amount of energy radiated into the environment is reduced.

See the SDMA white paper for more details

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