Described is a low latency re-timer for systems supporting spread spectrum clocking. The re-timer comprises: a first clock frequency estimator to estimate a frequency of a receive clock (RX CLK) and to provide a first timestamp associated with a first clock that underwent spread spectrum; a second clock frequency estimator to estimate a frequency of a transmit clock (TX CLK) and to provide a second timestamp associated with a second clock that underwent spread spectrum; and a comparator to compare the first timestamp with the second timestamp.

An improved method of hierarchical output queueing of packets for a network scheduler of a network gateway that determines delays needed to conform to applicable rate shaping, and enqueues the packets based on the delay. Queues are associated with different classes of service (CoS), and within each class, each queue has a different scheduled time upon which it becomes available for dequeuing. A single set of CoS queues can support a large number of devices, improving the efficiency of software-based queuing by reducing the number of queues and simplifying queue polling.

In order to make it possible to control a delay jitter in packet transmission control, a packet control system (1) includes: an acquisition unit (11) that acquires a packet associated with a delay jitter which is requested; an enqueue unit (12) that enqueues the packet into a queue at a level which corresponds to the delay jitter associated with the packet among a plurality of queues which are classified into levels such that delay jitters are different for the respective levels; and a dequeue unit (13) that dequeues, in accordance with a dequeue timing specified for the queue, the packet which has been enqueued into the queue at the level corresponding to the delay jitter associated with the packet, and that sends the packet which has been dequeued to a network.

An improved method of hierarchical output queuing of packets for a network scheduler of a network gateway that determines delays needed to conform to applicable rate shaping, and enqueues the packets based on the delay. Queues are associated with different classes of service (CoS), and within each class, each queue has a different scheduled time upon which it becomes available for dequeuing. A single set of CoS queues can support a large number of devices, improving the efficiency of software-based queuing by reducing the number of queues and simplifying queue polling.

In accordance with an example embodiment of the present invention, disclosed is a method and an apparatus thereof for removing jitter introduced by a packet switched network. Each received audio frame comprises a primary portion and a redundancy portion. The redundancy portion comprises a partial redundant copy of a previous frame that is offset by k frames. If a frame n is lost, a frame n+k that comprises the partial redundant copy of the lost frame n, is located in a jitter buffer. Based on the frame n+k, a substitute frame n substituting the lost frame n is created and a substitution indicator of the substitute frame n is set to indicate that the redundancy portion of the substitute fame n should be used in decoding.

In accordance with an example embodiment of the present invention, disclosed is a method and an apparatus thereof for removing jitter introduced by a packet switched network. Each received audio frame comprises a primary portion and a redundancy portion. The redundancy portion comprises a partial redundant copy of a previous frame that is offset by k frames. If a frame n is lost, a frame n+k that comprises the partial redundant copy of the lost frame n, is located in a jitter buffer. Based on the frame n+k, a substitute frame n substituting the lost frame n is created and a substitution indicator of the substitute frame n is set to indicate that the redundancy portion of the substitute fame n should be used in decoding.

Described is a low latency re-timer for systems supporting spread spectrum clocking. The re-timer comprises: a first clock frequency estimator to estimate a frequency of a receive clock (RX CLK) and to provide a first timestamp associated with a first clock that underwent spread spectrum; a second clock frequency estimator to estimate a frequency of a transmit clock (TX CLK) and to provide a second timestamp associated with a second clock that underwent spread spectrum; and a comparator to compare the first timestamp with the second timestamp.

A real-time Ethernet (RTE) protocol includes start-up frames originated by a master device for network initialization including a preamble, destination address (DA), source address (SA), a type field, and a status field including state information that indicates a current protocol state that the Ethernet network is in for the slave devices to translate for dynamically switching to one of a plurality of provided frame forwarding modes. The start-up frames include device Discovery frames at power up, Parameterization frames that distribute network parameters, and Time Synchronization frames including the master's time and unique assigned communication time slots for each slave device. After the initialization at least one data exchange frame is transmitted exclusive of SA and DA including a preamble that comprises a header that differentiates between master and slave, a type field, a status field excluding the current protocol state, and a data payload.

A jitter compensation during receipt of voice content (1, 2, 3, 4) via IP-based networks in voice packets (110, 120; 210) with a header (H) and payload (PL) is described, wherein a piece of time information of a transmitter time of a transmitter, which indicates the time of sending (ts) of the voice packet (110, 120; 210), is contained in the voice packet (110, 120; 210). It is provided that the receiver initializes a receiver clock using a transmitter time by means of the time information in the initial packet, that the receiver determines a minimum relative packet transmission duration (delta) after the initialization of the receiver clock, adjusts the receiver time as a function of the minimum relative packet transmission duration (delta), during the receipt of a first voice packet (111) with voice content, determines the actual time of receipt of this voice packet and determines the buffer (DJB) as a function of the actual time of receipt (FIG. 4).

A jitter compensation during receipt of voice content (1, 2, 3, 4) via IP-based networks in voice packets (110, 120; 210) with a header (H) and payload (PL) is described, wherein a piece of time information of a transmitter time of a transmitter, which indicates the time of sending (ts) of the voice packet (110, 120; 210), is contained in the voice packet (110, 120; 210). It is provided that the receiver initializes a receiver clock using a transmitter time by means of the time information in the initial packet, that the receiver determines a minimum relative packet transmission duration (delta) after the initialization of the receiver clock, adjusts the receiver time as a function of the minimum relative packet transmission duration (delta), during the receipt of a first voice packet (111) with voice content, determines the actual time of receipt of this voice packet and determines the buffer (DJB) as a function of the actual time of receipt (FIG. 4).