Segmenting, multiplexing and transporting user data packets in a telecommunication system that employs Asynchronous Transfer Mode can be accomplished more effectively by assigning a transmission priority code to each segmented user data packet based on the type of data contained therein. Data that is highly sensitive to transmission delays (e.g., voice data) will be assigned a high priority, while data that is less sensitive to transmission delays (e.g., signal strength measurement data) will be assigned a lower priority. When the user data packet segments are assembled into segment minicells and multiplexed into the ATM cell stream, those with the highest priority will be inserted first so that they experience the least amount of transmission delay.

Multiplexing of voice and data minicells

An SCSA RX/TX memory (220) receives voice data and stores voice data samples under established voice channel identifiers. A controller (240) selects voice channels, and their associated voice data, for inclusion in an ATM cell. The memory (220) sends the voice channel identifier and the voice data for the selected channels to a Constant Bit Rate Segmentation And Reassembly (CBR SAR) circuit (225). The CBR SAR aggregates the voice data into an appropriate number of ATM cell slots for each of those voice channels. The CBR SAR 225 sends the aggregated information to a Multiplexer/Duplicator Circuit (MUX/DUP) (230) which assembles the ATM cell, and sends the completed ATM cell to an ATM transceiver (265) for transmission. When there is no voice data to be sent information data from an Available Bit Rate (ABR) SAR (260) is assembled to form an ATM cell to be sent by the ATM transceiver. The MUX/DUP also receives an ATM cell from the ATM transceiver, duplicates the ATM cell, sends one copy of the ATM cell to the CBR SAR, and one copy of the ATM cell to the ABR SAR. The SARs disassemble the ATM cell, verify the channel identifiers, and route any valid channel identifiers and associated data to their respective memories. The SCSA memory attaches a channel identifier number to each voice data sample and sends the combination to the SCSA interface, which then places the combination on the SCSA port (210). A host device causes the information data to be read from the DATA memory via PCI ports (245) via a DMA operation.

Transmission of voice over an asynchronous network

A network arrangement for transporting service (Servco) traffic between terminals via an asynchronous path comprises a Servco access layer incorporating multimedia gateways for access by said terminals, an asynchronous network layer, a service layer incorporating adaptation layer switches each coupled to the network layer, and a transport layer providing a connection medium between the adaptation layer switches. The Servco traffic is carried in ATM minicells over the network layer.

Digital communications system

A pulse code modulation modem system is configured to transmit data from a first modem to a second modem over the public switched telephone network (PSTN). The PSTN employs robbed bit signaling (RBS) such that symbols affected by RBS arrive at the second modem in a periodic manner based on a period of six symbols. The modem system is configured such that signal segments are formatted and transmitted with six symbols per segment. After obtaining symbol synchronization, the second modem initializes a modulo-6 symbol counter such that the zero count corresponds to the first symbol of each received signal segment. Those symbols affected by RBS are identified and analyzed to determine optimized signal point constellations that may be used to compensate for the RBS on a symbol-by-symbol basis during subsequent encoding and decoding. Upon a loss of synchronization, the second modem resets its modulo-6 counter in response to the detection of the first symbol in a subsequent signal segment. In this manner, the modem system can again use the optimized signal point constellations determined previously.

Method and apparatus for synchronizing a data communication system to a periodic digital impairment

In a publically switched telephone network (PSTN), a method and a system for simultaneously and independently multiplexing voice and non-voice data over a single, commonly shared PSTN access line This is accomplished by packetizing the voice and non-voice data into minicells, and then multiplexing the minicells into a single data stream for transportation across the commonly shared PSTN access line Once the minicells containing either voice or non-voice data have been transported over the single, commonly shared PSTN access line, the data is simultaneously and independently routed to distinctly different end-users according to the routing information stored in the header portion of each minicell

Simultaneous transmission of voice and non-voice data on a single narrowband connection

An ATM call interworking with the public switched telephone network may experience echo problems due to impedance mismatch. The authors propose two echo control designs to assure the quality of voice services by reducing round-trip echo delay. Performance of these two echo control designs is then analyzed. >

Performance analysis of two echo control designs in ATM networks

http://ieeexplore.ieee.org/iel3/5090/13882/00639795.pdf

Lung-Sing Liang

Papers

Performance analysis of two echo control designs in ATM networks

Performance Analysis of Two Echo Control Designs in Atm Networks