192 results about "Transmission latency" patented technology

A method for stream synchronization of real-time multimedia transport over a packet network, in which the multimedia includes a first stream and a second stream which are buffered and played through buffers. The method includes: measuring average transport delays of the first and second streams; measuring transport delay jitters of the first and second streams; and calculating a delay difference between the first and second streams which corresponds to the average transport delays and the transport delay jitters of the first and second streams, and setting buffer durations. A device for stream synchronization of real-time multimedia transport over a packet network is also provided.

Described are computer-based methods and apparatuses, including computer program products, for deterministically skewing transmission of content streams. A content stream comprising one or more video frames is received. The content stream is buffered in a buffer, wherein the buffer allows simultaneous read access to the content stream at a plurality of locations. One or more video frames of the content stream are transmitted from the buffer to a first device associated with a first subscriber beginning at a first location in the buffer based on a first transmission delay parameter. One or more video frames of the content stream are transmitted from the buffer to a second device associated with a second subscriber beginning at a second location in the buffer based on a second transmission delay parameter.

Effective bandwidth of a communication link is determined in a heterogeneous, packet switched network between a source and a destination, where effective bandwidth is defined as the actual available bandwidth between the server and the client, minus the overhead of the various network protocols used to transmit the data. The method includes measuring transmission times between the source and a destination for a plurality data segments having different characteristics, such as different sized files or subfiles of data; processing the transmission times to cancel effects of transmission latencies other than the different characteristics of the data segments; and indicating a bandwidth based on said processing. The processing is done in parallel with the return of user resources to the destination, and using a bandwidth detection engine associated with a proxy server.

The present invention is to provide a method and device which can determine current available bandwidth for each Transport Control Protocol (TCP) connection and adjust window size dynamically according to the available bandwidth to achieve high network utilization and efficient flow control in the same time without the need to buffer any received TCP packets, which can work with and without support of large window option. The device classifies incoming traffic into several groups (public and private), monitors and allocates the available bandwidth for each group. To enable flow control, the device also records the initial window size value for each connection and compares it with the original window size value for a newly received TCP packet. If the original window size value received from TCP receivers changes, the device varies the modified window size accordingly to enable efficient flow control in the same device as well.

Embodiments of the present invention set forth a method and system for reducing uncertainty in receive and transmit timestamps created by an NTP server. The uncertainty in the receive timestamps is removed by recording the time-of-arrival in the hardware clock of the NTP server before the incoming packets may be delayed by traversing the various layers of software in a timestamping system. The uncertainty in the transmit timestamps is removed by giving the outgoing packets a timestamp in the future using an estimate of the transmission latency calculated by the latency estimator filter. Subsequently, the actual time-of-departure is used to re-calculate and update the estimate of the transmission latency. In this fashion, superior control of the timestamping function may be implemented in existing NTP servers in a manner that retains interworking compatibility with the current NTP standards.

The present invention describes a method and apparatus for reducing the access-delay and transmission latency in a system where a network terminal modem terminates to a network over a transmission media. In a network the processing of input data to be transmitted as processed data on the transmission media is synchronized with a time period when the transmission media is to be allocated for transmitting the processed data. Synchronization is achieved by determining when access to the transmission media will be granted for transmitting the processed data and synchronizing the processing of the input data with the determined time. Thereby the synchronizing results in the processing being completed at a time relatively close to the time when access to the transmission media is granted. Thus the need to store the processed data awaiting transmission is significantly reduced and thereby reducing the access delay and transmission latency.

A system and method for selectively handling requests for dynamic data processing. In the system and method, requests for dynamic data processing can be received in an origin server, but the dynamic data processing can be deferred to an edge server in those circumstances where it is dynamically determined that the edge server is capable of performing such dynamic data processing. In this way, network transmission latencies can be avoided by performing dynamic data processing in those edge servers closest to the requesting user.

Without using additional probing packets, estimates of the narrow link bandwidth and available bandwidth of a network path are computed based on existing traffic. The network can be of different types such as a wireless battlefield network context or a wired or wireless commercial network environment. “Fast packets”, i.e. those packets which do not experience any queuing delay in the network, are identified. Fast packets are identified to resolve end-to-end packet delay into its constituent components (deterministic, transmission and queuing delays), estimate path utilization and eliminate the uncertainty (false alarms) that causes the prior art method to lose its effectiveness. An estimation algorithm computes end-to-end transmission delay and end-to-end deterministic delay of fast packets traveling along a path in a network. Examples of deterministic delay include satellite propagation delays and clock effects. Then, based on the results of the fast packet identifying algorithm, two logic branches are followed. A first branch calculates utilization and a second branch calculates narrow link bandwidth. The narrow link bandwidth is determined from the packet pair dispersion. The available bandwidth is obtained from the narrow link bandwidth and the utilization. Estimation of available bandwidth for an end-to-end network path allows traffic sources to judiciously regulate the volume of application traffic injected into the network.

A system using scheduled times for transmission at each link guarantees bandwidth for transmitting data across a packet network. A scheduling agent determines availability of data paths across a network according to pre-selected criteria and real-time network topology information. Precise schedules are determined for transmission and reception appointments for data packets to traverse each link and switch in the network including compensation for transmission delays and switch latencies, resulting in a fixed packet flow itinerary for each connection. Itineraries are communicated to schedule-aware switches and endpoints and appointment times are reserved for transmission of the scheduled data packets. Scheduled packets arriving at each switch are forwarded according to their predetermined arrival and departure schedules, rather than their headers or contents, relieving the switches from making real-time routing decisions. Any unscheduled transmission times remain available for routing of unscheduled packets according to their IP headers. Real-time transmission of data can be guaranteed in each scheduled path, and schedule selection criteria may be adjusted according to network utilization and tolerable setup delay and end-to-end delay.

An intelligent switching system and method provides an alternate, least-cost telecommunications link (which may be a wireless link) between a base transceiver station (BTS) and a base station controller (BSC) in a radio access network (RAN). Signals may be routed via the alternate telecommunications link or via an existing telecommunications link based on the sensitivity of the signals to transmission latency. The switching system may determine the sensitivity of the signals to transmission latency.

A wireless local area network comprising a plurality of computing entities communicating over a common communications frequency within a local area network operates a transmission deferral method whereby each computing entity defers its own transmissions if it receives a signal at said communications frequency which is above a threshold value set within said computing entity, and which is decodable. Each computing entity is capable of varying dynamically the value of its threshold level above which receipt of signals results in the computing entity deferring its own transmission. Received signals on the communications frequency which are less than the threshold value do not result in the computing entity deferring its transmissions, but are ignored by the computing entity. The threshold value is varied according to whether traffic from more remote signal sources are sufficiently intense that the local traffic cannot be decoded.

In an environment with large transmission delays, use of an OFDM transmitter which includes: a pilot/data allocator for allocating pilot/data symbols on OFDM symbols and an OFDM receiver which includes: an antenna for receiving the OFDM signals sent out from the antenna of this OFDM transmitter; a ratio unit for frequency transforming the OFDM signals received as RF signals to baseband signals; a frequency offset estimate for estimating an offset value; and a frequency offset corrector for performing frequency compensation by the amount of the frequency offset, improves data transmission efficiency while reducing interference of data between sub-carriers to prevent degradation of reception characteristics by performing appropriate frequency offset correction.

An Apparatus for non-linear per-bin adaptive equalization in orthogonal multi-carrier data transmission systems with the Nyquist sub-channel spectral shaping and T/2 staggering of in-phase and quadrature components is disclosed. A previously introduced linear equalization embodiments are augmented by up to three, or more decision feed-back filters, to improve performance in presence of narrow-band interference (NBI) in wire-line and wire-less data transmission systems, and to enable exploitation of implicit diversity of multi-path fading channels, both with and without transmitter-end pre-coding. Adaptation properties of per-bin DFE equalization are analyzed by computer simulation for an intermediate number of constituent sub-channels. BER performance comparison between the conventional Orthogonal Frequency Division Multiplication-(OFDM) and (Orthogonal Quadrature Amplitude Modulation (OQAM)-based multi-carrier systems of similar modulation/demodulation complexity and transmission latency is provided and the potential advantage of using spectrally well shaped orthogonal sub-channels in wireless applications is demonstrated.

Provided are a node device and a method for deciding a shortest path using a spanning tree. The node device includes: a node division unit dividing the node device into sub-nodes as many as the number of nodes connected to the node device when the node device operates an edge node that is located at an end of a backbone network and is in charge of reformatting and routing frames; a spanning tree generation unit generating as many spanning trees as the number of sub-nodes, wherein each of the spanning trees comprises a shortest path to reach the other edge nodes constructing the backbone network from each of the sub-nodes; and a first path decision unit deciding a shortest path from a source node to a predetermined destination node, as a path to be used, based on the spanning trees that are generated by the spanning tree generation unit. The shortest path that is obtained based on the plurality of spanning trees is used as a path to be used such that throughput of traffic is 3 times and 1.5 times larger than in existing STP and SPB, respectively, and the transmission delay is smaller than in existing STP and SPB. In addition, packet loss is smaller than in STP and SPB, and the node device and the method for deciding a shortest path using a spanning tree are robust to the unbalanced traffic.