Abstract: A method and apparatus to reduce background noise in speech signals in order to improve the quality and intelligibility of processed speech. In mobile communications environment, speech signals are degraded by additive random noise. A randomness of the noise, which is often described in terms of its first and second order statistics, make it difficult to remove much of the noise without introducing background artifacts. This is particularly true for lower signal to background noise ratios. The method and apparatus provides noise reduction without any knowledge of the signal to background noise ratio.

Abstract: In a multiple-user network communication system such as a satellite-based system, or in cable or wireless systems, the system resources, such as bandwidth, code allocation, and or slot timing, are allocated to users based in part on their class of service. The allocation provides for immediate allocation of the requested resources to a user having a verified high class of service so long as the resources are abatable or can be made available by tapping a resource reserve. If only a portion of the requested resources are available, they are made available immediately. From time to time, the resources available to at least one class of service are allocated among the users of that class of service, either equally, equally up to the requested resources, equitably, or in some systematic manner.

Abstract: The present invention uses low temperature co-fired ceramic (LTCC) technology for fabrication of micro-electro-mechnical systems (MEMS) based phase shifters. As a result, low-cost subarray modules can be constructed using LTCC, and the subarray modules (10) can be used as building blocks for large antenna arrays. In an exemplary description of the present invention, all layers of the multilayer subarray modules, including MEMS, are in LTCC. As a result, a significant cost reduction for satellite terminals using highly integrated LTCC subarray modules.

Abstract: A phased array antenna (100) comprising a planar array having a plurality of modules (101,102,103). Each module comprises an integrated multilayer structure having a plurality of radiating elements (215), at least one of the layers is produced using MEMS technology. Further, each module has at least one of a plurality of phase shifters (220,221,222), a plurality of power dividers (230,231,232), a plurality of polarization circuits (and a plurality of filters (240,241,242)). The modules are coupled, both mechanically and electrically, to a distribution network (110) for distribution of DC signals and RF signals. At least one amplifier (121,122,123) is connected between the distribution network and the modules or a single amplifier is connected to the whole array.

Abstract: A Fast Fourier Transform (FFT) arrangement for use in those situations in which not all of the outputs are desired is controlled in such a fashion that at least those multiplications (and possibly those additions) are not performed which do not contribute toward the desired outputs. The technique is usable in those situations in which the desired output signals are noncontiguous, or are in noncontiguous bins. The technique includes signal preprocessing in which the indices are adjusted so that the index for a particular stage points to those butterflies of the previous stage which contribute toward its output. The FFT is performed on the indexed data. In one embodiment, a pipelined FFT processor is controlled in a corresponding manner.

Abstract: An adaptive intelligent radio module (IRM) is provided in an intelligent radio design for gateways between satellite and terrestrial networks. The intelligent radio module monitors channel signal quality at the channel units of the gateway to determine whether the quality of a channel unit is below a predetermined quality threshold. If the channel quality is greater than or equal to the predetermined quality threshold, then a standard channel unit is employed, and nominal algorithms are used to process the channel. However, if the channel quality is below the quality threshold, then a high performance channel unit is used that employs complex algorithms unique to the particular quality defect of the channel quality. Various additional functions can be performed at the receive side and the transmit side of the channel units monitored by the IRM. Further, the IRM can add or enhance existing algorithms in accordance with new technology.

Abstract: A digitally implemented demodulator (FIG. 1) produces initial detection estimates (180) and transition estimates (23) of symbols sampled in the range lying between 1 and 2 complex samples per symbols of the received carrier (14I), (14Q). In the case of detection estimate, the second-occurring of the two estimated values is selected as the correct value when there are two samples in the symbol interval. In the case the transition time estimate, the first-occurring of the two estimated values is selected as the correct timing estimate.

Abstract: This disclosure describes a method to generate large numbers of spot beams for multiple-beam satellite systems using smaller apertures. This is done by dividing the basic spot beam that has 3 to 4 dB of gain drop within the beam into a number of smaller 1-dB sub-beams. This has the effect of reducing the required peak gain for the antenna by 2–3 dB, thus reducing its size by as much as 50%. The frequency band allocated to the basic beam will be divided among the sub-beams. However, the frequency re-use among the basic beams can be maintained. Frequency allocations have to be coordinated among all beams. This concept is especially applicable to phased arrays using digital beam formers. The DBF complexity is a function of the number of array elements, and is less dependent on the number of beams. Reducing the array size, and consequently reducing the number of elements helps in reducing the complexity, power and mass of the DBF.

Abstract: An apparatus for compressing the header of ATM cells in order to provide greater bandwidth includes means for discriminating cells/packets (1310), means for detecting header (1320), means for compressing header (1330), means for combining compressed header with payload (1350), means for discriminating compressed header cell/packet (1710), means for detecting header in compressed header and separating header from payload (1720), means for decompressing header (1730), and means for combining decompressed header with payload (1740) to form cell/packets.

Abstract: To efficiently transmit frame relay packets between terrestrial frame relay networks (10, 12) over a satellite/wireless network (14), the packets are processed by frame relay processors (16, 18) at both ends of the satellite/wireless network (14). Variable length frame relay packets are segmented into smaller packets called spackets. The system utilizes priority queueing and a scheduler (24) transmits the spackets over the satellite/wireless link. To enhance the quality of the satellite/wireless link, each frame contains a variable number of Reed-Solomon (RS) check bytes used for error correction. Further, several frames are interleaved before transmission over the satellite/wireless link to spread the effect of burst errors over several frames. Additionally, a header compression technique saves bandwidth by compressing a Virtual Circuit (VC) identifier of the frame relay packet into a smaller value and maps the VCs to a value as specified by the size of the compressed VC field.

Abstract: A telecommunications network including sub-telecommunications networks for transferring information including packet data which comprises one or more mobile stations, a first sub-telecommunications network, and a second sub-telecommunications network interconnected with the first sub-telecommunications network. The network further includes a number of gateway GPRS support nodes, and one or more gateway GPRS support nodes corresponding to each of the first sub-telecommunications network and the second sub-telecommunications network. Each of the gateway GPRS support nodes is operable to provide interworking between the first and the second sub-telecommunications networks and external packet data networks. The network also includes a system controlled in accordance with a procedure for transferring packet data within a multi-country telecommunications network.

Abstract: According to an exemplary embodiment an architecture for a new integrated TDMA system capable of carrying circuit data (e.g., voice, vides, ISDN), packet data (e.g., X.25, Frame Relay, Internet, LAN), and ATM cells is disclosed. The architecture may be used for satellite and wireless TDMA networks, for example. For this transmission formats for bursts (101), channels (130, 140), TDMA frames (10) are defined and an adaptation layer for the three traffic types is described. In addition, the network has to carry its own management traffic and provide timing and control information to all terminals. For this the invention defines special bursts and along with their associated properties and formats. Each burst contains a data section which is divided into a number of channels.

Abstract: A method and apparatus for providing for segmentation, reassembly and inverse multiplexing of variable sized packets and ATM cells over satellite and wireless links. Variable sized packets are divided into segments having a size equal to that of an ATM cell and are arranged in a segmentation and reassembly (SAR) frame having in its overhead an indication as to the length and unique identity of the frame, each segment also having a header that uniquely identifies the segment, the destination and the origination of the packet from which the segment originates. A terminal id is also used to identify the unit, site and control group from which the segment originates so that the information can be transmitted on the basis of available bandwidth on demand.

Abstract: A lost frame recovery technique for LPC-based systems employs interpolation of parameters from previous and subsequent good frames, selective attenuation of frame energy when the energy of a subframe exceeds a threshold, and energy tapering in the presence of multiple successive lost frames.

Abstract: A lithium-ion cell includes a carbonaceous anode and a lithiated metal oxide cathode, with a plastic spacer therebetween and liquid electrolyte containing lithium salts. The cell stands for a period of time aller electrolyte is added. The cell is then charged at a first current density of about ¼ mA/cm2 for at least an hour. Following the first charge, the cell stands open-circuited for at least an hour. The cell is again charged, at a current density significantly greater than the first current density, until the cell reaches a particular voltage which corresponds with the desired cell capacity, and gases are vented. After the second charge, the cell is discharged at a relatively high current density toward a particular voltage, so as to leave less active lithium ions in the anode structure. After discharge, the lithium ion cell is sealed and ready for charging by a user.

Abstract: The present invention relates to burst mode digital communication systems where data transmission is preceded by a preamble for acquisition of carrier and clock synchronization using maximum likelihood (ML) principle. The preamble is sampled and the set of samples obtained is processed using the optimization algorithms of the present invention to provide the ML timing estimate. The optimization algorithms in the present invention consist of three parts. The first part deals with isolating the desired optimal estimate from non-optimal extremes satisfying the same necessary condition, and provides the initial conditions for activating the binary search schemes. The second part performs the binary search for the optimal timing estimate that guarantees the convergence. On the basis of the obtained iterative sequence, the last part constructs a more rapidly convergent sequence to obtain the ML symbol timing estimate.

Abstract: A method and apparatus for providing frame acquisition and synchronization for ATM transmissions in terrestrial wireless and satellite systems. During acquisition (1020), the transmitter (15) fills the entire payload of a frame with a pattern that is used by the receiver (18) to determine the location of the frame boundary. As to synchronization (1020), a procedure is utilized for using frame sequence number field in the header and Reed-Solomon decoding result (1012) for correction and maintaining frame synchronization.

Abstract: An apparatus and method for providing bandwidth on demand service in a wireless communication system having at least one user station, including a frequency divider for dividing a selected bandwidth into a plurality of frequency subdivisions. Also included is a unit for assigning a first number of frequency subdivisions to the individual user stations having a first total bandwidth, commensurate with the volume of transmission traffic. There also is a unit for changing the first number to a second number having a second total bandwidth commensurate with the change of the volume of transmission traffic.

Abstract: A method and device for measurement and reduction of frequency offset in a communication network having a master reference terminal and at least one terminal exchanging reference and control bursts includes steps for adjusting demodulator frequency in the terminal responsive to a first frequency error between a first nominal frequency value and a respective reference burst received by the terminal, and adjusting modulator frequency at the terminal responsive to a second frequency error between a second nominal frequency value and a control burst generated by the master reference terminal and transmitted to the terminal.

Abstract: The present invention provides a method to achieve frame synchronization from a received data sequence before the carrier phase and frequency offset recovery for any MPSK modulated signals on the basis of maximum likelihood theory. Two overhead configurations are considered in developing the frame synchronization algorithms. One overhead configuration consists of a unique word followed by a preamble, and the other consists of unique word only. For the first overhead, the frame synchronization can be decoupled from carrier recovery because the preamble following the unique word is a known sequence pattern. In this case, the maximum-likelihood frame synchronization rule is simply a complex correlation. In second overhead, the unique word is immediately followed by random traffic data and thus the coupling effects are generated between frame synchronization and carrier recovery. These coupling effects are not dominant, however, and may be neglected in actual practice.