Abstract: A contention based communications channel access method emulates scheduled access by dynamically updating Enhanced Distribution Channel Access (EDCA) parameters for groups of member stations in a Wireless Local Area Network (WLAN).

Abstract: A cellular arrangement where, when a cell phone is in a region where it may be served by two bases stations, it switches its mode of operation to space-time coding where the space diversity for such coding is obtained by using the antennas of the two base stations.

Abstract: The present invention provides methods and apparatuses for verifying that a transaction is legitimate. The methods and apparatuses use protected memory space, such as kernel space of an operating system, or a separate memory space, such as is available on a SIM card of a cellular phone. The method of the invention proceeds by creating a transaction identification string (TID) and associating the TID with a transaction. The TID contains data relevant to or associated with the transaction and is typically readable by an end-user. The transaction is then interrupted until a user responds in the affirmative to allow completion of the transaction. Methods and devices used in the invention are particularly well suited to M-commerce, where transactions originating from a device are typically recognized by a merchant as coming from the owner of the device without further authentication.

Abstract: A data transmission system includes a low bandwidth two way transmission network which is employed to arrange access to and use of a wide bandwidth bearer channel to facilitate the transmission of data at a wide bandwidth enhancing the efficiency of data transmission. In one embodiment, a low bandwidth telecommunication service is used to set up a wide band channel connection on a wide band telecommunication service to allow the user to communicate high speed data without the necessity of overhead addressing and accessing communications on that channel.

Abstract: A wireless broadband communication system architecture is structured to provide an array of narrowband and broadband services to an end user on demand. The bandwidth of delivery is dynamically adjusted to deliver and satisfy service requirements by utilizing the appropriate bandwidth on demand. Bandwidth-on-demand is provided in accord with the invention by rearranging spectrum allocations so that a particular band spectrum is convertibly used to accomplish different purposes depending on present allocations and active applications of the system. The communications system is designed to utilize wireless communication for end point delivery to both fixed and potable terminals. The system supplies basic telephone service, wireless ISDN service, wireless data service, wireless multimedia service and various other wireless broadband service including types of interactive and broadcast video.

Abstract: A universal wireless radiotelephone communication apparatus is operative in both a first radiotelephone communication system including a first base station having a wide area of coverage, transmitting radiotelephone signals at a first band of frequencies and in a second radiotelephone communication system including a second base station having a localized area of coverage, transmitting radiotelephone signals at a second band of frequencies higher than said first band of frequencies. The second band of frequencies is optimally selected with an offset of less than twice a frequency contained within said first band.

Abstract: A universal wireless radiotelephone communication apparatus is operative in both a first radiotelephone communication system including a first base station having a wide area of coverage, transmitting radiotelephone signals at a first band of frequencies and in a second radiotelephone communication system including a second base station having a localized area of coverage, transmitting radiotelephone signals at a second band of frequencies higher than said first band of frequencies. The second band of frequencies is optimally selected with an offset of less than twice a frequency contained within said first band. The wireless radiotelephone communication apparatus has a common baseband circuitry for operating with both the first base station covering the wide area and with the second base station covering the local area.

Abstract: A personal communicator handset is designed to operate as both a handset and as a speakerphone and to automatically switch between the two modes based on distance between the handset and the user's ear. This distance is determined by an infrared range detection unit built into the handset.

Abstract: An automatic calibration system for a second-order gradient microphone is provided to ensure optimum sensitivity balance between a pair of first-order gradient microphones mounted in a housing and forming the second-order gradient microphone. Automatic calibration is achieved through use of a transducer also mounted in the housing and located equidistant acoustically between the two first-order gradient microphones. Under the control of a computer, the transducer is directed to generated sound pressure which is used to calibrate the gain of amplifiers respectively associated with each one of the first-order gradient microphones for obtaining maximum directional sensitivity for a second-order directional response pattern. Such a system not only allows the use of inexpensive, non-matched microphones, but also obviates the need for factory calibration.

Abstract: An improved switched-loss, adaptive speakerphone dynamically adjusts its switching thresholds and other performance parameters based on an analysis of acoustic environment and telephone line conditions. To access these conditions, the speakerphone utilizes a computer with associated firmware. As part of a calibration process, the speakerphone computes its thresholds before each use to compensate for possible variations in hardware circuitry therein. This is achieved by passing a first and then a second level of a test tone signal through the hardware circuitry and measuring the resulting response. The speakerphone also measures the acoustics of the room in which it operates as part of the calibration process. For this measurement, a tone burst signal is generated through a loudspeaker in the speakerphone and measured by a microphone also in the speakerphone. A time-domain acoustic response of the room is obtained which provides to the computer the amplitude of the return signal and the duration of its echo.

Abstract: An adaptive speakerphone employs an echo suppression arrangement which compensates for a reverberant effect that occurs during operation of the speakerphone in a near full or full duplex mode. This reverberant effect allows the far-end party to hear his or her own echo from the near-end location. The arrangement includes an echo suppression process which compensates for this effect by inserting loss in the transmit path of the speakerphone as appropriate. Operation of this process is such that whenever the speakerphone is in the receive state, the levels of a transmit and receive speech signal in the speakerphone are monitored. By monitoring these speech signal levels, the process determines when speech into a microphone in the speakerphone is being coupled from a loudspeaker also in the speakerphone and when the transmit speech signal level exceeds a predetermined threshold. If this threshold is exceeded, then loss that tracks an envelope of the receive speech signal is inserted in the transmit path.

Abstract: An acoustic calibration circuit in a voice switched adaptive speakerphone accurately determines the type of acoustic environment in which the speakerphone is employed. The calibration circuit measures the acoustics of the room by emitting a tone burst through a loudspeaker associated with the speakerphone and measuring the returned time-domain acoustic response with a microphone also associated with the speakerphone. Obtained from this response and processed by a computer in the speakerphone are the maximum amplitude of the returned signal, and the duration of the echoes. The amplitude of the returned signal determines what level of transmit speech will be required to break in on receive speech. The greater the acoustic return, the higher that threshold must be to protect against self-switching. And the duration of the echoes determine how quickly speech energy injected into the room will dissipate, which, in turn, controls how fast the speakerphone can switch from a receive to a transmit state.

Abstract: A circuit for maximizing power transfer from a station to an interactive memory card via a capacitive interface. A reader system in the station generates an ac signal which provides operating power that is transferred to the card through the capacitive interface formed when the card is placed against a window on the station. The ac signal from the station is directed through a series resonant circuit to the card. The capacitive interface between the station and card make up the capacitive element of the resonance circuit while the series combination of the secondary of a transformer and an electrically variable inductor form the inductive element. Use of the variable inductor allows the station to tune the circuit to resonance and cancel the capacitive element, thereby maintaining maximum power transfer to the card.