Hughes Electronics Corporation

Hughes Aircraft Company

Kalyan Ganesan

Ranjan Pant

Tayyab Khan

Prabhat K Gupta

Kumar Swaminathan

Victor Liau

Harry M Johnson

Kim Goh

Desmond Coughlin

Barrie Saunders

Robert Fischler

Enrique Laborde

Andrew W Barnhart

Ho Lee

Gregory Federline

P Vijay Kumar

Barry Saunders

Desmond Coghlan

A system and method for integrating advanced messaging capabilities in a wide area wireless personal communications system is provided. The system includes personal transceiver units capable of communicating with one or more of a plurality of long range pagers. The transceiver and long range pager use existing frequencies and formats of the wireless personal communications system. The method provides for registering a personal transceiver in a two way messaging service area of the wireless personal communications system.

System and method for a wide area wireless personal communication system incorporating advanced messaging

The present invention relates to a wireless personal communications system (WPCS) having several features embodied in several forms. In one embodiment, the, WPCS includes at least one RP, a first SU in communication with the RP, and a second SU in communication with the first SU through the RP without involving the RPC in the manner contemplated by the specification. The RP may preferably include a channel switching unit for connecting the first SU with the second SU without using any tariff lines to or from an RPC. Such an RP may be used as a component in a wireless PBX or Centrex system including ISDN based systems. Another preferred embodiment provides for a walkie-talkie option where the first SU communicates directly with the second SU, preferably over an unlicensed frequency. In another preferred embodiment, a plurality of SUs in communication with an RP may be accessed individually using a single dialed number.

Wireless personal communication system

A preferred embodiment provides a radio port controller in a wireless personal communications system including a first interface module in communication with a radio port, a second interface in communication with a digital switch, and at least one switching transcoder module in communication with the first and second interface modules. A further preferred embodiment provides that the switching transcoder module includes a digital signal processor. The radio port controller preferably has a communication backplane including a plurality of slots, and each slot is preferably adapted to selectively receive either a T1 card interfacing to a T1 line or an E1 card interfacing to an E1 line.

Radio port controller in a wireless personal communications system

The present invention relates to a subscriber unit in a wireless personal communications system (WPCS). In one embodiment, the subscriber unit includes a digital dataport for modemless communication of digital signals. Another preferred embodiment provides for a subscriber unit having a cable television transport module for modulating and demodulating signals over unused bandwidth available on cable television lines.

Subscriber unit in a wireless personal communication system

The present invention relates to a radio port in a wireless personal communications system. The radio port includes a first channel in communication with a first subscriber unit, a second channel in communication with a second subscriber unit, and a switching device connecting the first channel to the second channel so that the first subscriber unit may communicate directly with the second subscriber unit. In another preferred embodiment, the radio port includes a plurality of antennas, an RF receive section, an RF transmit section, an analog port adapted for connection to an analog telephone line, a digital dataport for receiving and transmitting digital signals, and a databus interconnecting the RF receive section, RF transmit section, analog port, and digital dataport. The RF receive section includes a diversity selection unit receiving an input signal from each of the antennas. The RF transmit section generates an output signal to be transmitted over at least one of the antennas.

Radio port in a wireless personal communication system

A bit rate Codebook Excited Linear Predictor (CELP) communication system which includes a transmitter that organizes a signal containing speech into frames of 40 millisecond duration, and classifies each frame as one of three modes: voiced and stationary, unvoiced or transient, and background noise.

Voiced, unvoiced or noise modes in a CELP vocoder

Radio port controller in a wireless personal communication system

An improved error control coding scheme is implemented in low bit rate coders in order to improve their performance in the presence of transmission errors typical of the digital cellular channel. The error control coding scheme exploits the nonlinear block codes (NBCs) for purposes of tailoring those codes to a fading channel in order to provide superior error protection to the compressed half rate speech data. For a half rate speech codec assumed to have a frame size of 40 ms, the speech encoder puts out a fixed number of bits per 40 ms. These bits are divided into three distinct classes, referred to as Class 1, Class 2 and Class 3 bits. A subset of the Class 1 bits are further protected by a CRC for error detection purposes. The Class 1 bits and the CRC bits are encoded by a rate 1/2 Nordstrom Robinson code with codeword length of 16. The Class 2 bits are encoded by a punctured version of the Nordstrom Robinson code. It has an effective rate of 8/14 with a codeword length 14. The Class 3 bits are left unprotected. The coded Class 1 plus CRC bits, coded Class 2 bits, and the Class 3 bits are mixed in an interleaving array of size 16.times.17 and interleaved over two slots in a manner that optimally divides each codeword between the two slots. At the receiver the coded Class 1 plus CRC bits, coded Class 2 bits, and Class 3 bits are extracted after de-interleaving.

High performance error control coding in channel encoders and decoders

The perception of speech processed by a CELP based coder, such as a VSELP coder, when operating in noisy background conditions is improved by removing swirl artifacts during silence periods. This is done by removing the low frequency components of the input signal when no speech is detected. A speech activity detector distinguishes between a periodic signal, like speech, and a non-periodic signal, like noise by using most of the VSELP coder internal parameters to determine the speech or non-speech conditions. To prevent the VSELP coder from determining pitches for non-periodic signals, a high pass filter is applied to the input signal to remove the pitch information for which the VSELP coder searches.

Removal of swirl artifacts from celp-based speech coders

A method for encoding a signal that includes a speech component is described. First and second linear prediction windows of a frame are analyzed to generate sets of filter coefficients. First and second pitch analysis windows of the frame are analyzed to generate pitch estimates. The frame is classified in one of at least two modes, e.g. voiced, unvoiced and noise modes, based, for example, on pitch stationarity, short-term level gradient or zero crossing rate. Then the frame is encoded using the filter coefficients and pitch estimates in a particular manner depending upon the mode determination for the frame, preferably employing CELP based encoding algorithms.

Mode-specific method and apparatus for encoding signals containing speech

A multimedia codec for a frame relay network. Multiple information media from different sight equipment is converted to a standard packet for transmission over said frame relay network. Incoming frames are processed on a priority basis and stored in an elastic buffer. Tests of pointers are kept for each media type identifying the location in the elastic buffer of the various packets for the different media. Applications running in the frame relay processor retrieve the stored media data and forward it to a digital signal processor connected to respective terminal equipment.

Growing community of inventors

Germantown, MD, United States of America

Kalyan Ganesan