Koninklijke Philips Corporation N.v.

U.S. Philips Corporation

Leon Steiner

Samir N Hulyalkar

Elik Shekhter

A prioritized buffer for the Medium Access Control (MAC) layer for multimedia applications, in particular wireless Asynchronous Transfer Mode (ATM) in which reservation based TDMA is performed on the basis of control data frames (CDFs), is formed by an addressable memory system which is divided into sequential equal-sized pages for storing respective data packets or ATM cells having the same number of bytes. The memory system includes a tag register for storing tags associated with the respective pages, each tag indicating whether the associated page is empty or full, a shadow register for storing conflict-free updates from the tag register, and a page register for storing pointers to the lowest free or unoccupied page. Sequential buffer addresses of memory locations in the memory system, which control sequential writing into the buffer of bytes contained in data packets, are generated from summing a first address component responsive to the contents of the page register and a second address component which is a byte count of a current packet being received from a stream data source. A succession of byte addresses is produced which jumps over addresses within pages which are full, thereby bypassing and avoiding overwriting pages which are full.

Prioritized-buffer management for fixed sized packets in multimedia application

A method for synchronizing timestamps in a network (e.g., a wireless ATM network) that includes a control node and a plurality of other nodes that communicate with one another over a common channel mediated by a medium-access control subsystem (e.g., one that uses a reservation-based TDMA protocol). The method includes the steps of sending a first command from the control node, at a first time, then storing a starting timestamp value in a register within the control node and each of the other nodes, in response to the first command, and then sending a second command from the control node, at a second time later than the first time. Each of the other nodes computes the difference between the starting timestamp value and a current timestamp value, and then adds the computed difference to the current timestamp value. In an alternative embodiment, the control node sends a preset command and each of the other nodes presets their respective timestamp to a prescribed initial timestamp value, in response to the preset command. Each of the nodes periodically compares a current timestamp counter value with a prescribed reset value, and upon detecting a coincidence, sets a sync flag latch to indicate that a next timestamp value correction is to be made, in response to a next preset command. Networks that implement the above-described methods are also disclosed.

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Yorktown Heights, NY, United States of America

Leon Steiner