Abstract: A method and apparatus for extending the sequence numbering range for a selective repeat transmission protocol is described. In accordance with one embodiment of the invention, data frames are transmitted including an eight-bit sequence number and a one-bit retransmit flag. The one bit retransmit flag indicates whether the frame is newly transmitted or retransmitted due to a failed first transmission. The transmit and receive systems each maintain a twelve-bit sequence number referred to as “long sequence numbers” comprised of the eight-bit sequence number transmitted with each frame and a four-bit extension. The long sequence number is transmitted within control frames and the eight-bit sequence number is transmitted within the data frames.

Abstract: A method and apparatus for extending the sequence numbering range for a selective repeat transmission protocol is described. In accordance with one embodiment of the invention, data frames are transmitted including an eight-bit sequence number and a one-bit retransmit flag. The one bit retransmit flag indicates whether the frame is newly transmitted or retransmitted due to a failed first transmission. The transmit and receive systems each maintain a twelve-bit sequence number referred to as a "long sequence numbers" comprised of the eight-bit sequence number transmitted with each frame and a four-bit extension. The long sequence number is transmitted within control frames and the eight-bit sequence number is transmitted within the data frames.

Abstract: Buffer memory overflow control is realized by controlling the amount of packet data being inputted to the buffer memory in response to the amount of packet data stored in the buffer memory. Depending on the type of coding being employed and the amount of data stored in the buffer memory, one or more groups of bits are controllably dropped from the packet information field being inputted into the buffer memory.

Abstract: Delay that a packet experiences in a network node is measured by employing a single local time signal in the node, and by separating a time stamp update function into a network node entry stamp function and a network node exit time stamp function. The node entry time stamp function is to generate a packet originate time value referenced to the local time signal value upon the packet entering the node. This packet originate time value is inserted into a packet header time stamp field to be transported through the node. The node exit time stamp function is to generate an updated time stamp value from the packet originate time value from the header time stamp field and the local time signal value upon the packet exiting the node. The undated time stamp value is inserted into the packet header time stamp field in place of the packet originate time value.

Abstract: Unwanted distortion in signals being reconstructed from packets is substantially eliminated by employing a virtual sequence packet numbering scheme in conjunction with a time stamp value. A virtual sequence number which accompanies the packet identifies the location of the packet in an information spurt. If the packet is the initial packet in the information spurt, the time stamp value is used to "build out" the delay experienced by the packet to a fixed overall value. Subsequent packets in the information spurt are concatenated to the information spurt. A packet following one or more lost packets is also identified by the packet virual sequence number and is also treated as an initial packet.

Abstract: A packet information field format is disclosed which facilitates packet buffer memory overflow control. Generation of the information field is such that like bits from samples representing a corresponding communication channel from a plurality of frames are grouped together. In a specific embodiment, the bits from the communication channel samples are arranged in groups including the most significant bits to the least significant bits. The packet header also includes a field which can have an indication therein of whether bits can be dropped from the packet and an indication of whether bits have already been dropped from the packet. Consequently, dropping of bits from the packet is readily achieved by first dropping the group including the least significant bits, then dropping the group including the next to least significant bits, if necessary, and so on until it is determined that the entire packet should be dropped, if necessary.

Abstract: Circuits at a remote transmission site receive digitized voice and data samples from incoming channels. The voice samples are compressed. The samples are formatted into fixed-size data blocks with signaling and control information for transmission to a switching node. Additional bits of the voice samples are dynamically dropped, if necessary, to fit the data into the fixed-sized blocks. The signaling and control information allows receiving circuits at the switching node to determine the number of bits allocated to each sample. These receiving circuits form packets for individual channels by attaching switch routing packet headers to the individual channel data. Packet receiving circuits on the output side of the switch reformat the received packets into fixed-size nonpacket data blocks for transmission.

Abstract: Improved efficiency in allocating bits to individual ones of a plurality of sub-band signals (or amplitude coefficients) is realized by employing a so-called template matching technique. A plurality of the most likely to occur bit allocation patterns and a corresponding plurality of templates including representations of a prescribed characteristic of the sub-band signals that would generate a corresponding one of the bit allocation patterns are stored for later use. Selection of a bit allocation pattern for use in encoding and/or decoding the sub-band signals is effected by matching in accordance with a given one of the stored templates to representations of the prescribed characteristic of the sub-band signals presently being encoded. In one example, the prescribed characteristic is a power estimate and the matching criterion is a minimum rate distortion criterion.

Abstract: Adaptive bit allocation to a set of spectral transform coefficients is optimized by setting a predetermined first (maximum) threshold, then allocating one bit to those coefficients above the threshold, no bits to those below. If the total number of bits has not been allocated, the threshold is lowered an "integer" step to a second threshold, and again one bit allocated to those coefficients above the second threshold. The procedure is iterated until all the total bits are allocated or, if too many bits are allocated after the last integer step, a "fractional" step threshold is used.