Abstract: A user terminal can be authenticated by an access point based on one message. In one embodiment, the present invention includes the access point receiving a message containing a shared secret encrypted with an access point public key, a user terminal certificate, and an authenticator string demonstrating possession by the user terminal of a user terminal private key. The access point can decrypt the shared secret using the private key of the access point paired with its private key. The access point can then authenticate the user terminal by checking the authenticator string using a user terminal public key included in the user terminal certificate to verify possession of the user terminal private key by the user terminal.

Abstract: The certificate issued by a certificate authority used in authenticating a user terminal can be scrambled prior to being set to an access point. In one embodiment, the present invention includes a user terminal having a memory in which a user terminal certificate is stored. The user terminal also has a processor coupled to the memory to scramble the user terminal certificate using a shared secret to be known only by the user terminal and an access point of the wireless access network, and a transmitter coupled to the processor to send a message to the access point, the message including the scrambled user terminal certificate.

Abstract: The time reference of a user terminal that is derived from an unauthenticated access point can be certified by a trusted entity according to the present invention. In one embodiment, the present invention includes a user terminal obtaining a time reference from an access point of a wireless access network. The user terminal then receives a digital certificate having a validity period from the access point, the certificate being issued by a certificate authority. In one embodiment, the user terminal requests certification of the time reference by a trusted entity, and receives the certification. Then the user terminal can validate the digital certificate.

Abstract: A user terminal can be authenticated by an access point based on one message. In one embodiment, the present invention includes the access point receiving a message containing a shared secret encrypted with an access point public key, a user terminal certificate, and an authenticator string demonstrating possession by the user terminal of a user terminal private key. The access point can decrypt the shared secret using the private key of the access point paired with its private key. The access point can then authenticate the user terminal by checking the authenticator string using a user terminal public key included in the user terminal certificate to verify possession of the user terminal private key by the user terminal.

Abstract: A method for use in a communication network having multiple users and limited bandwidth, wherein up to N users are allocated to the same frequency band at the same time, and the method provides for processing signals received at an M-element antenna array, using a cumulant-based signal recovery system to separate and recover the signals transmitted by the respective users.

Abstract: Method and apparatus for separating signals transmitted over a waveguide using different propagation modes in overlapping frequency bands. The signals are received at an array of probes installed in an operative relationship to the waveguide, and are separated using a recovery system based on cumulants of the fourth or higher even order.

Abstract: Apparatus for transmitting and receiving signals over a fiber-optic waveguide using different frequency bands of light, i.e. by wavelength division multiplexing. A plurality of signal couplers interfaces modulated signals onto the waveguide in separate optical frequency bands, and a plurality of signal probes forming a probe array at one or more places in the waveguide, receives the signals, which are subject to scrambling and distortion as a result of physical irregularities in the waveguide. A recovery system coupled to the signal probes effects recovery and separation of the received signals using cumulant computations based on cumulants of the fourth or higher even order.

Abstract: Method and apparatus for complex phase equalization in a communication system. The method includes receiving and downconverting a two-dimensional communication signal to generate in-phase (I) and quadrature (Q) components that have been phase-rotated by an unknown amount during propagation from a transmitter, and then processing the I and Q signals in a cumulant recovery processing system to obtain phase correction of the I and Q signals prior to demodulation. The final step is demodulating the two-dimensional communication signal. Phase correction is effected without regard to modulation type and independently of the demodulating step.

Abstract: A method and apparatus for processing cochannel signals received at a sensor array in a cumulant-based signal processing and separation engine to obtain a desired set of output signals or parameters. For use in a signal recovery system, the output signals are recovered and separated versions of the originally transmitted cochannel signals. An important feature that distinguishes the cumulant-based system from other signal separation and recovery systems is that it generates an estimated generalized steering vector associated with each signal source, and representative of all received coherent signal components attributable to the source. This feature enables the invention to perform well in multipath conditions, by combining all coherent multipath components from the same source. In a receiver/transmitter system, the estimated generalized steering vectors associated with each source are used to generate transmit beamformer weight vectors that permit cochannel transmission to multiple user stations.