Ncr Corporation

Lucent Technologies Inc.

Agere Systems Inc.

Agere Systems Guardian Corp.

Hans Van Driest

Hendrik Van Bokhorst

Adriaan Kamerman

Wilhelmus J M Diepstraten

Jan Boer

Wilhelmus J Diepstraten

Robert John Kopmeiners

Bruce T Tuch

Richard Kruithof

Johan O Hilbrink

Donald W Carr

Rienk Mud

Francis J McFadden

Johannes P Haagh

Jacobus C Haartsen

Gerrit Smit

Maarten Visee

Wilhelmus Josephus Diepstraten

In one embodiment, a method of transmitting data from a transmitter in a wireless local area network (WLAN), where the transmitter has a timer and a modem. The transmitter periodically transmits a transmission signal that includes a timestamp field that includes a timestamp for synchronizing a receiver timer in a receiver of the WLAN. The timestamp, which represents a value within the count sequence of the transmitter timer, accounts for delays in the modem.

Wireless local area network apparatus

A wireless local area network apparatus includes a transmitter and a receiver in which operation of the receiver is accurately synchronized with periodic signals from the transmitter. The periodic signals contain timing data indicating the state of a timer in the transmitter at the time the signal containing that data was transmitted and this timing data is retrieved from the signal when received by the receiver and loaded in a timer for controlling operation of the receiver.

The timing of a carrier signal is tracked in a receiver. The receiver receives a signal produced by a transmitter having a single frequency source which is used to generate a reference clock frequency and a carrier signal frequency, there being a fixed, predetermined relationship between the reference and carrier frequencies. In the receiver there is a single frequency source which is used to generate a reference clock frequency and a carrier reference signal frequency, there being a fixed, predetermined relationship between the reference and carrier reference frequencies. The fixed, predetermined relationship in the transmitter and the receiver is the same.

Tracking carrier timing

A system for, and method of, generating a spread spectrum code position modulated waveform and a wireless local area network (LAN) containing the system or the method. The system includes: (1) a spread-spectrum encoder that receives and encodes portions of an information signal with a multi-chip code having a predetermined length to create therefrom a stream of sequences, each of the sequences having the predetermined length and (2) a transmitter that periodically transmits the each of the sequences at a time interval that differs from the predetermined length, a data rate of transmission of the information signal thereby allowed to increase.

System and method for spread spectrum code position modulation and

A receiver, and a method for operating the receiver, for a station in a wireless local area network using a common wireless communication channel and employing a CSMA/CA (carrier sense multiple access with collision avoidance) protocol includes various modes. In normal mode, the receiver follows typical states in order to detect a message and demodulate data from the message properly. Meanwhile, a process implements a message-in-message (MIM) mode when an energy increase above a specified level is detected. While in the MIM mode, if a carrier is detected, the energy increase is caused by a new message; otherwise, the energy increase is caused by an interfering station. If the carrier is detected, the receiver begins retraining so that it can start receiving the new message as soon as the first message ends. If no carrier is detected, the receiver waits a specified time to detect a carrier or for the end of the first message, after which the receiver returns to the beginning of the normal mode. While in the normal mode, if a message is detected that is not addressed to the station, the receiver enters a hunt mode. While in the hunt mode, the receiver waits for the current message to finish. At the same time, a process implements retraining when both an energy increase above a specified level and a carrier are detected. If no carrier is detected within a specified time, or if the energy level decreases below the specified level, the receiver returns to the beginning of the normal mode.

Wireless lan with enhanced capture provision

For use in an automatic gain control that receives a digital signal from a digital circuit having a given dynamic range and develops therefrom a gain signal to be applied to a variable gain amplifier, an analyzing circuit for, and method of, determining a magnitude of the gain signal. The analyzing circuit includes: (1) a peak sampling subcircuit that determines an average peak value of the digital signal over variable periods of time and (2) a gain signal adjustment subcircuit, coupled to the peak sampling subcircuit, that operates in a selected one of: (a) a search mode in which the gain signal adjustment subcircuit decreases the periods of time and adjusts the gain signal at a first rate until the average peak value falls within the dynamic range of the digital circuit and (b) a direct step mode in which the gain signal adjustment subcircuit increases the periods of time and adjusts the gain signal at a second rate as a function of a deviation of the average peak value from a target average peak value, the first rate being faster than the second rate, the analyzing circuit thereby applying a two-stage gain determination process to the digital signal to approach the target average peak value.

Digital automatic gain control employing two-stage gain-determination

For use in a direct sequence spread spectrum ('DSSS') receiver adapted to receive a differential phase shift keyed ('DPSK') packet on a channel, the DPSK packet having a training preamble and a data portion, a system to improve detection of the packet under degraded channel conditions, comprising: (1) a detection circuit that derives phase information from symbols in the packet and a weight that is a function of an estimated power profile for the channel and (2) a computation circuit that computes a weighted average for the phase information using the weight, the weighted average being power profile-based to allow the receiver to detect the data contained in the packet more reliably under the degraded channel conditions.

System and method for improved spread spectrum signal detection

A wireless pointing device which sits in the palm of a user's hand. The palm mouse includes a first portion which includes a ball for generating pointing signals, a control circuit for processing the pointing signals, a top section having a top surface which is generally ovoid in shape, and a bottom section having a bottom surface which is generally flat in shape and which contains an aperture through which the ball protrudes. A second portion includes a J-shaped flexible member attached to the first portion for cupping the hand. A communication circuit includes a transmitter within the first portion, a first antenna within the J-shaped member, a power supply within the first portion, a receiver coupled to the computer, and a second antenna coupled to the receiver. A preferred embodiment of the palm mouse has at least one switch on the J-shaped member, which is activated by the user's thumb.

Palm mouse

A wireless LAN includes first stations adapted to operate at a 1 or a 2 Mbps data rate and second stations adapted to operate at a 1,2,5 or 8 Mbps data rate. The 1 and 2 Mbps rates use DBPSK and DQPSK modulation, respectively. The 5 and 8 Mbps rates use PPM/DQPSK modulation. All four data rates use direct sequence spread spectrum (DSSS) coding. All transmitted messages start with a preamble and header at the 1 Mbps rate. The header includes fields identifying the data rate for the data portion of the message, and a length field. For a 2 Mbps transmission the length field identifies the number of bytes in the data field. For a 5 or 8 Mbps the length field identifies the number of bytes in the data field which, if transmitted at 2 Mbps, would take the same transmission time of the data field, and is thus a fraction 2/5 or 2/8 of the actual number of the bytes. With this arrangements, all the stations are interoperable in a co-existent manner in the LAN.

Multirate wireless data communication system

In a local area network station (12) for a wireless LAN, a threshold level circuit (62) includes a register (134) which stores a threshold value. The station receiver (42) monitors the transmission channel and provides a receive level signal indicative of the signal level received. Transmission of a data frame by the station transmitter (46) is permitted or deferred according as the receive level signal value is below or above the threshold level, regardless of whether or not the received signal derives from a transmission by a station in the receiving station's own LAN. The threshold is dynamically updated whenever the station (12) receives a data frame from its own LAN. An improved utilization of the wireless transmission channel is achieved.

Transmission control for a wireless local area network station

A local area network station (12) includes a transceiver (20) adapted to transmit and receive signals using electromagnetic radiation on a wireless communication link. The station (12) utilizes a CSMA/CD communications controller (22) in a CSMA/CA (collison avoidance) technique wherein deferred data frames are transmitted after a random number of backoff slots periods. A plurality of antennas (14, 16) is employed, with the antenna having the best receive conditions being selected for reception of a data frame. The antennas having a slotting control (200) which is synchronized with the backoff slotting to provide a short carrier detect time and hence high throughpout.

Antenna control for a wireless local area network station

A radio LAN station is provided for receiving information frames including start and end delimiters and user data therebetween. The start and end delimiters include both data symbols and special non-data symbols. The data symbols and non-data symbols being transmitted to the radio LAN station are sent thereto via a spread spectrum signal. The data symbols and the non-data symbols are spread via first and second spreading codes, respectively. The receiving radio LAN station includes first and second correlators which respectively correlate the received spread spectrum signal against the first spreading code to retrieve the data symbols and against the second spreading code to retrieve the non-data symbols. Rectangular representations of the received data and non-data symbols are thus produced and are converted to polar form via appropriate rectangular to polar converters. The polar representations of the data and non-data symbols respectively exhibit a vector length Z and a vector length Z'. The receiving LAN station includes circuitry for determining that a symbol is a data symbol if Z - Z' is greater than or equal to a constant A, or that a symbol is a non-data symbol if Z - Z1 is less than said constant A. In this manner, the data and non-data symbols representing the start and end delimiters are detected.

Radio LAN station with improved frame delimiter detection in a spread

A local area network (10) utilizes a wireless transmission link and has network stations (12) each having two differently polarized antennas (14, 16). Data transmission utilizes a spread spectrum code and in the receiver, correlator outputs are utilized in an integrator and registers circuit (54) to provide correlator output sample values integrated over a plurality of symbol intervals. These values are stored in registers (156) the contents of which are utilized to determine a peak value and a total value which are applied to a spike quality determination circuit (78) including a look-up table (200). The resultant spike quality output value represents the quality of the received signal and is utilized for carrier detection and for antenna selection.

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Bilthoven, Netherlands

Hans Van Driest