Telefonaktiebolaget Lm Ericsson (publ)

Lars-Goran Petersen

Lars Goran Eneroth

Juan Noguera-Rodriguez

Lars Westberg

Sture G Roos

Erik O Abefelt

Mats C Olstedt

Ulf M Adamsson

Martin P Ljungberg

A method for mapping a plurality of minicells into a channel structure is disclosed. The channel structure has a plurality of multi-frames with each multi-frame having a plurality of time slots. A start octet is inserted in a first time slot of each multi-frame and the sequence number within the start octet is used to count the number of multi-frames.

AAL2 framing on NX64 KBPS E1/T1

In a telecommunications network, broken connections can be detected and located through a next hop loopback technique. The next hop loopback technique involves the generation, transmission, and analysis of specialized data packets which attempt to traverse a telecommunications connection, node by node. The failure of a data packet to properly traverse a link can then be used to determine whether a connection is broken, to notify the network management system as to the location of the broken connection, and whether appropriate action is warranted so that the network operator can re-route data around that portion of the network. In addition, the next hop loopback technique can be triggered on an 'as needed' basis by the end user, rather than on a periodic basis, thereby conserving network time and resources.

Next hop loopback

In a telecommunications network, segments along a telecommunications connection causing data corruption or data degradation can be detected and precisely identified through a segment performance monitoring technique. The segment performance monitoring technique involves the generation, transmission, and analysis of specialized data packets which traverse a telecommunications connection node by node. At each node, a value for one or more segment performance characterization factors is accumulated based upon a predefined block of user-assigned data packets. Degradation of the data caused by any segment along the telecommunications connection can be determined, in part, by comparing the value for the one or more segment performance characterization factors to one or more performance characterization factor values generated by a source node.

Segment performance monitoring

In a telecommunication system that employs asynchronous transfer mode (ATM) and minicells to transport communication data, accurate minicell header information dramatically improves the ability to align the minicells at a receiving station. More accurate minicell header information can be achieved by deriving a single header integrity check code (e.g., a cyclic redundancy code) for each ATM cell based upon minicell headers that have been inserted into contiguous locations in the ATM cell. By inserting the headers in contiguous locations, the receiving station can extract each header without having to rely upon the length indicator codes in each header, which may contain one or more bit errors. This, in turn, allows the receiving station to recompute the header integrity check code with far fewer errors, thus substantially increasing the probability of detecting and correcting the aforementioned errors and, ultimately, the ability to align the minicells.

Minicell alignment

A telecommunication system has a sending entity, a receiving entity, and an ATM link between the sending and receiving entities for transferring ATM cells on specific separate ATM connections. The ATM cells include user ATM cells having a header and payload containing data in the form of a determined number of data units which carry data in microcells. The header includes an ATM connection pointer. The microcells have payload for carrying a variable size user data package and a microcell header containing code identifying a microcell connection. A microcell unable to fit in its entirety in a remaining space of an ATM cell belonging to a certain ATM connection is divided into a first part located in a least on following ATM cell belonging to the same ATM connection. Microcell size information is associated with each microcell. Methods for finding microcell boundaries are provided.

Telecommunication system and a method for transferring microcells therein

In a telecommunication system that generates more than one type of communication data stream, in which each data stream exhibits a distinctive data transfer format, bandwidth utilization is improved by first reformatting the different data transfer formats so that all of the data is compatible with a common data transfer protocol, for example, the Asynchronous Transfer Mode (ATM) protocol. The communication data and the corresponding control data, required to maintain communication data alignment, are multiplexed into a single data stream which is then transmitted over a common telecommunication channel to a receiving station.

Hybrid ATM adaptation layer

In a telecommunication system that uses asynchronous transfer mode (ATM) with the ATM adaption layer (AALm) protocol as a data transfer infrastructure, a method and apparatus for segmenting and reassembling user data packets. The method and apparatus improve the quality and effectiveness of telecommunication data transfer by avoiding the problems associated with excessively long minicells.

Minicell segmentation and reassembly

When using asynchronous transfer mode (ATM) in low bit rate applications, such as cellular voice communication, bandwidth utilization is significantly improved by employing decoupling minicells. Decoupling minicells are of predetermined length, such as one octet, and are inserted into the payload of ATM cells when there is a delay in the availability of assigned minicells. As soon as an assigned minicell, which contains actual user data, becomes available, the assigned minicell can be inserted into the payload of the current ATM cell immediately after the last decoupling minicell. Unlike prior methods, there is no need to wait until the next ATM cell to insert an assigned minicell.

ATM method and apparatus utilizing decoupling minicells

A method for switching synchronous transfer mode cells in a circuit emulated ATM switch using a layered protocol model. Each cell is delivered to the circuit emulated ATM switch on a frame oriented basis and each such cell comprises a header and a payload. The header comprises fields storing details about the cell. The payload comprises time slots carrying user data. The ATM switch is provided with means for assigning a predetermined number of time slots to a cell that is transported on a physical medium. The cell, referred to as a PR-PDU-cell, can have any of a number of sizes ranging from 4, 8, 12, 16, 20, 56 and 60 octets. This reduces the packetizing time of a cell.

Circuit emulating exchange using micro cells

The process of detecting lost data cells in a telecommunication system that employs Asynchronous Transfer Mode is significantly improved in terms of bandwidth utilization by using an optional minicell or ATM cell sequence count. This may be accomplished by inserting the minicell or ATM cell sequence count into the ATM cell stream at intervals that can be adjusted at the transmitting station.

Minicell sequence number count

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

A system for controlling the flow of data cells through a packet switch combines both input and output buffers in a feedback loop. The fullness level of output buffers is continuously monitored and reported to an access device on the input side of the switch. The access device includes input buffers and a throttling device to stop the flow of data cells, and hold them in the input buffers, when the fullness level of the output buffers exceeds a predetermined level. A status message of output buffer fullness is compared to an access message indicating which output buffers are addressed by cells in the input buffers, and only those cells addressed to overfull output buffers are stopped by the throttling device. The efficiency of the packet switch is improved over switches using input buffers alone. The required capacity of the output buffers is reduced, thereby making it easier and less expensive to provide the required bandwidth.

Flow control system for packet switches

An asynchronous transfer mode (ATM) switch in which access to a switchcore matrix is monitored and controlled through the logic and buffering functions of switchports connected thereto. The switchcore is greatly simplified by moving the logic and buffering functions to the switchports. The switchcore matrix comprises a plurality of rows, columns, and crosspoints thereof, providing routing paths for the routing of information cells from input points to output points on the matrix. Single-cell buffers in the switchcore matrix enable temporary storage and hand-off of individual information cells as they pass through the matrix. The simplicity of the switchcore matrix enables it to be constructed on a single integrated circuit.

Controlled access ATM switch

A circuit switch connected between transmitting and receiving devices includes a switch memory including a number of memory positions for entering of received time slot data from the transmitting devices, a control memory including a number of memory positions for entering read-out addresses for the switch memory, an addressing path from the control memory to the switch memory for a read-out address in the latter, from which read-out of data shall be made towards a receiving device, and a control unit for entering the read-out addresses in the control memory and for receiving information from the devices related to the connect and disconnect of calls. The addressing path from the control memory has an alternative communication path towards the receiving devices, and each memory position in the control memory includes a specific position for an indicator bit containing information with respect to whether read-out of time slot data should be made from the switch memory or from the control memory.

Generating idle codes in switches

A digital switch serves a number of terminal units for switching signal traffic therebetween, the traffic being logically divided into data time slots and control time slots with control packets. It comprises a switch memory for receiving the data time slots, a control memory containing information for facilitating through connection of the data time slots in the switch memory, a control memory terminal for receiving the control time slots and control packets located therein, for writing information into the control memory, and for transmitting acknowledgement packets to called and calling ones of the terminal units, and an occupied/unoccupied memory cooperating with the control memory terminal and storing actual status of each of the terminal units. A queue system is associated with the control memory terminal and the occupied/unoccupied memory, the queue system including memory and control logic for effecting, in case a first terminal unit tries to establish connection to a second terminal unit that is occupied, queueing of a call request and transmission to the first terminal unit of an acknowledgement 'request for connection queued' and, at the receipt of a request for disconnection from the second terminal unit, direct connection of the first terminal unit to the second terminal unit, and transmission of acknowledgements to the first and second terminal units with the information 'connection effected' and 'request effected', respectively.

Growing community of inventors

Tumba, Sweden

Lars-Goran Petersen