Abstract:
A multimedia communications and computer platform that can serve as a network interface card combined with an internal distribution network for a full range of user terminal devices. It includes an interconnection network module that serves to route all incoming and outgoing information by way of high speed buses with value added features for communication protocol acceleration. In particular, attached to the different ports of the network are an ATM module, a communications processor, a media processor and a variety of terminal devices. By migrating processing intensive functions of network protocol termination, media stream distribution and media stream adaptation into the network interface card, there are avoided the bottlenecks of the traditional CPU centric approach to ATM systems.
Abstract:
An improved time division multiple access (TDMA) satellite transmission system uses N TDMA stations and employs a signal format in which successive time frames begin with a header containing synchronizing and control signals generated by a selected TDMA and followed by N time slots, and in which each TDMA station generates and transmits data packets having a high energy level during a unique time slot assigned to each TDMA and in which each TDMA transmits data packets only during its assigned time slot, and further in which at least some of the TDMA's do not transmit data packets in the available time during the assigned time slot, thereby leaving unpredictably occurring idle time. Apparatus is provided for using a substantial portion of the idle time. The apparatus includes a plurality of random access terminals (RATS) each constructed to generate and transmit a data packet, having a lower energy level then the TDMA energy level, to any given single time slot during each frame and logic apparatus is provided for selecting such given single time slot on a predetermined statistical basis. Each RAT is capable of receiving all successfully transmitted data packets and determines the successful or non-successful transmission of any data packet originating therefrom. Data is retransmitted by the RAT's during a subsequent frame when the originally scheduled RAT transmission is not successfully completed.
Abstract:
An access point of a wireless network including: a controller for emulating a first virtual access point of a first service provider and a second virtual access point of second service provider; a transceiver port for communicating control signals to clients of the first and service providers to limit the uplink air-time of the clients; and a connection port for linking the first and second service providers to a backhaul.
Abstract:
Disclosed are the design and implementation of a CSI feedback channel in a multi-carrier wireless communication system. An apparatus and a method for channel state feedback using arithmetic coding are provided to ensure efficiency and reliability of a system by transmitting the CSI while compressing the CSI with a predetermined compression rate selected depending on a channel state. The apparatus for CSI feedback in a wireless communication system performing channel estimation at a transmitter or a receiver by using a communication channel includes a transmitter terminal transmitting a signal for CSI measurement by using the communication channel, and a receiver terminal receiving the signal from the transmitter terminal, checking a channel state based on the received signal, and transmitting the signal to the transmitter terminal after compressing the signal according to the channel state.
Abstract:
An asynchronous transfer mode (ATM) traffic control framework is based on an integrated usage parameter control (UPC) approach, which approach provides a unified and scalable solution to the issue of quality-of-services (QOS) levels over a range of anticipated services in ATM based networks. The approach is consistent with emerging ATM Forum and CCITT standards. Additionally, a UPC-based call and burst admission control providing the desired QOS over periods of network overload by call/burst admission control and traffic shaping of source stream preferably uses a dual leaky bucket.
Abstract:
Apparatus for encoding/decoding a HDTV signal for e.g., terrestrial transmission includes a compression circuit responsive to high definition video source signals for providing ierarchically layered codewords CW representing compressed video data and associated codewords T, defining the types of data represented by the codewords CW. A priority selection circuit, responsive to the codewords CW and T, parses the codewords CW into high and low priority codeword sequences wherein the high and low priority codeword sequences correspond to compressed video data of relatively greater and lesser importance to image reproduction respectively. A transport processor, responsive to the high and low priority codeword sequences, forms high and low priority transport blocks of high and low priority codewords respectively. Each transport block includes a header, codewords CW and error detection check bits. The respective transport blocks are applied to an forward error check circuit for applying additional error check data. Thereafter the high and low priority data are applied to a modem wherein they quadrature amplitude modulate respective carriers for transmission.
Abstract:
A CDMA network includes a retransmission scheduler which selectively delays the retransmission of an initially erroneously sent signal. The selected delays have an average value in a range of values which results in a single equilibrium point between input messages and output messages to avoid a bistable condition that can lower overall system throughput.
Abstract:
A random access communication system forms messages to be transmitted into subpackets of fixed duration. A message packet includes two or more subpackets. Each subpacket includes information relating to the source transmitter-receiver and the number of subpackets in the message. The subpackets of the message packet are transmitted contiguously over the transmission path in a contention mode. Some subpackets are successfully received and some are lost due to collisions. After a period of asynchronous contention operation, a predetermined number of subpackets are successfully received, and the system switches to a short-term synchronous, scheduled operating mode. In the scheduled operating mode, those transmitter-receivers which were the sources of message packets including some successful and some unsuccessful subpackets retransmit the data from the unsuccessful subpackets, ordering themselves in accordance with the order of receipt of successful subpackets. The system capacity is high, average delay is short and continuous global synchronization is not required.
Abstract:
An improved companded transmission system uses a transmitter having a first compressor for compressing a signal m(t) of bandwidth B.sub.1 to form a signal C[m(t)]. The transmission system has a bandwidth B.sub.2 where B.sub.1 .ltoreq.B.sub.2. A receiver having an expander to expand the received signal r(t) is provided to produce a signal m.sub.E (t). The improvement consists of a circuit for recovering the frequency components f.sub.L lost during transmission of C[m(t)] and includes a second compressor for compressing m.sub.E (t) in the same manner as m(t) was compressed to produce a signal C[m.sub.E (t)] which contains frequency components f.sub.c lying above B.sub.2. A filter which is responsive to C[m.sub.E (t)] generates (C[m.sub.E (t)]-f.sub.c), and, a subtractor subtracts (C[m.sub.E (t)]-f.sub.c) from C[m.sub.E (t)]. An adder adds f.sub.c to r(t), and, an expander expands the summed signal f.sub.c +r(t) to produce a signal m.sub.1 (t) which is a first order corrected approximation of m(t). Similar structure can iteratively process m.sub.1 (t) to further refine or correct the received signal.