Abstract: A method of reducing tunneling in a wireless packet network. The method includes defining a home access point for a client station, determining that the client station is being serviced by an access point different from the home access point, deciding if the client station should change its home access point to the access point from which the client station receives service and initiating a change of the home access point of the client station, if so decided.

Abstract: A channel access system is described in which a number of slots within a contention window are available for assignment to streaming data transmitters. The other slots are selected by the other transmitters according to a CSMA/CA transmit protocol.

Abstract: Orthogonal frequency division multiplexing (OFDM) receiver embodiments of the invention provide timing misalignment estimation by calculating the intra-baud timing differential. The preferred method exploits the spectral structure of the short-preamble in that a time delay in the time-domain is manifest as a phase rotation in the frequency-domain. The timing misalignment is determined by special processing the spectral peaks of the modified short-preamble. An alternative embodiment linearly combines the two long-preamble symbols to construct a single “best estimate” long-preamble symbol. A normalized dot product of the “best estimate” long-preamble symbol and the ideal on-baud symbol is computed to obtain the magnitude of the timing misalignment. A dot product between the “best estimate” long-preamble symbol and the time derivative of the ideal on-baud sampled sequence is computed to obtain the sign of the timing misalignment.

Abstract: A method and apparatus are provided that performs timing acquisition for multiple radio terminals. According to one aspect of the present invention the invention includes receiving a sequence of symbols modulated onto a carrier frequency over a channel and demodulating the symbols using a clock frequency. The invention further includes determining a frequency offset of the received symbols with respect to the clock frequency and applying the determined frequency offset to adjust the clock frequency.

Abstract: An apparatus and method for communicating data between at least two data devices, suitable for use as a wireless local-area network, that provides robust data communication via a radio communications channel corrupted by multipath interference, particularly at high data rates. A preferred embodiment of the invention represents data as a sequence of Walsh-function waveforms encoded by pseudo-noise direct-sequence spread-spectrum modulation. Walsh-function-encoding of the data provides a long symbol duration, thereby allowing the spread-spectrum modulation to provide processing gain sufficient to substantially overcome multipath interference, while providing a high data rate. In another preferred embodiment, Walsh-function modulation is supplemented with various forms of phase modulation, such as coherent PSK for bi-orthogonal signalling, and DPSK between orthogonal symbols for noncoherent bi-orthogonal signalling, thereby further increasing data rate without reducing processing gain.

Abstract: The present invention is directed to providing frequency hopping medium access control among a plurality of nodes (e.g., communication stations) in a wireless communication system. The present invention is directed to decentralized control of synchronization among the plural nodes. In accordance with exemplary embodiments, a node used to control synchronization of the communication system can switch from a first master node to a second master node.

Abstract: The present invention is directed to managing power consumption in a wireless frequency hopping communication among a plurality of nodes. For example, the present invention is directed to features such as reducing power consumption of an individual node within a wireless communication system by powering on the transmitter/receiver of the node only when actual transmission/reception is required.

Abstract: Roaming capability is provided to mobile computers within a standard network such as a Novell network. In a computer network running under a network operating system that provides for fault-tolerant internet routing of network communications between nodes and requires that network ID of a node remain constant for the duration of session, the nodes include multiple mobile computing devices wirelessly connected to the network. The mobile computing devices are provided with the capability to roam during a session by changing access points to the network. This capability is provided by programming the mobile computing devices so as to appear to the network as routers able to change access points during a session. The routers connect one sub-net to one other sub-net, the one sub-net being connected to a mobile computing device and having a fixed network ID and the other sub-net, through fault-tolerant internet routing being connected to a selectable access point and therefore having a variable network ID.

Abstract: A removable connectorized flexible, planar antenna and a removable tethered antenna which attach to a card radio for use in a wireless local area network is disclosed. The planar antenna has a latching mechanism with a pair of release levers which latch to slots in the frame of the card radio to provide an attachment strong enough to be used as an extraction handle for the card radio. The flexible antenna has a flexible sheet with a conductive material applied in a shape specified and connected to the card radio via a RF connection port. A removable tethered antenna is disclosed having at the base of the tethered antenna a dovetailed connector which releasably rotates within a mounting plate affixed to the back of the monitor on a mobile computer.

Abstract: The present invention is directed to providing wireless communication among a plurality of nodes and repeaters that are synchronized for communication with a central hub that constitutes a master repeater. For example, the present invention is directed to a wireless network having a wireless backbone of repeaters which can use frequency hopping to automatically establish synchronization despite dynamic changes in the wireless communication system. Exemplary embodiments provide for control of synchronization whereby a repeater, when introduced to the system, automatically scans for, and synchronizes to another repeater, while at the same time continuing to listen for other repeater signals which identify either the master repeater, or another repeater which is closer to the master repeater (i.e., communicates to the master repeater through a more direct communication link).

Abstract: The present invention is directed to providing a wireless medium access control protocol wherein throughput can be optimized as the communication system dynamically changes when nodes either join or leave the communication system.

Abstract: A signal transition control system for use in a modulated-signal communication system having a plurality of predefined signal states each representing a digital data symbol, enables a transition from one signal state to a next signal state to be executed in a smooth, bandwidth-efficient manner. The system includes circuitry for receiving a stream of data symbols and storing in succession consecutive pairs of the data symbols, each of the pairs including a last data symbol and a next data symbol, for producing data describing a vector in signal space from the last data symbol to the next data symbol, for storing data representative of a desired shape of a transition from the last data symbol to the next data symbol, means for sequentially stepping through the data representative of the desired shape, and for producing data representing a transition from the last data symbol to the next data symbol, the transition having the desired shape.

Abstract: An electronic, binary-controlled digital tapped delay line is realized by a plurality of like stages connected in cascade. Each stage comprises a differential amplifier circuit responsive to a pair of input signals for producing a pair of output signals and including a differential transistor pair. A first loading circuit formed by a plurality of load devices interconnected to produce a cumulative loading effect is connected to an input of a first transistor of the differential transistor pair for delaying turn-on of the first transistor. Similarly, a second loading circuit formed by a plurality of load devices interconnected to produce a cumulative loading is connected to an input of a second transistor of the differential transistor pair for delaying turn-on of the second transistor, the first and second loading circuits each being connected to a first circuit node.

Abstract: Digital frequency synthesizer and method in which an output signal of desired frequency is synthesized by periodically incrementing a count in steps corresponding to a desired output frequency, monitoring the count to determine when it reaches a level corresponding to a point at which a transition is desired in the output signal, providing a series of waveforms which are displaced in time and have transitions occurring at different times, and selecting the waveform which has a transition closest to the desired point as the output signal.

Abstract: Access to a radio communications medium shared by at least two agents to provide peer-to-peer communication therebetween is controlled by sensing the communications medium at a first agent to determine if the communications medium is in use, transmitting from the first agent, if the first agent determines that the communications medium is not in use, a request-to-send message that includes reservation duration information, and receiving the request-to-sent message at a second agent. The second agent then transmits a clear-to-send message including reservation duration information on behalf of the first agent, after which the first agent then transmits information to the second agent while a reservation duration indicated by the reservation duration information has not elapsed. A possible third agent within receiving range of only one of the first and second agents is thereby guaranteed to receive the reservation duration information and is expected to observe the reservation according to rules disclosed.

Abstract: A spread spectrum radio communication system includes a generator for generating a pseudo-random chipping sequence, a frequency spreader for combining digital data with the pseudo-random chipping sequence to produce a spread spectrum signal, a modulator for modulating the spread spectrum signal for broadcasting over a predefined frequency band, a demodulator for demodulating broadcast spread spectrum signals, a de-spreader that employs single bit quantization and oversampling for digitally correlating the output of the demodulator means with a pseudo-random chipping sequence, and an extractor for extracting clock and data signals from the output of the de-spreader. The chipping sequence is normally selected from a set of codes including an eleven-bit Barker code, its inverse and reversals of the inverse and non-inverse code.

Abstract: A synthesizer capable of generating a multiplicity of output frequency signals with 1 hertz resolution utilizing binary mathematics in a binary circuit. The apparatus includes providing to an accumulator a stable reference input signal having a frequency value of K, a defined value of 2.sup.N where N is an integer, a rollover value R equal to 2.sup.N minus the synthesizer modulus M and a desired output frequency signal having a value V selected from the range of integer values between 1 and K. The accumulator, at the rate of K, periodically increments the accumulator contents A by the value V, until the accumulated value exceeds 2.sup.N -1. The accumulator's content A is then set at the next cycle of the reference input signal K to a value of A-2.sup.N +R+V. A convertor converts the values of A into an output signal. In the preferred embodiment, the accumulator includes digital circuitry having 2.sup.N capacity and performs binary arithmetic to accomplish the accumulations.