Abstract: A method for a station to periodically broadcast messages over a wireless channel to communicate to multiple other stations who transmit on the same channel, the station becomes ready to broadcast at successive message activation times, at a message activation time the station performing a Multiple Access mechanism (930) to resolve channel access competition and the station subsequently starting transmission of a message, wherein at least two successive message activation times differ a random time interval.

Abstract: A method of determining a best-case response time of a first periodic task, the method comprising a first step based upon Rate Monotonic Analysis of determining the priorities of the tasks that have to be scheduled on a system. In order to determine whether the set of tasks can be scheduled on the system, the best-vase response time in addition to the worst-case response time is determined per task. This best-case response time is substantially equal to the difference between the start of a task with a lower priority and the completion of this low priority task, the start being right after the release of the low priority task and the completion coinciding with the simultaneous release all higher priority tasks.

Abstract: In consumer devices, like digital television sets or set-top boxes, there can be a problem with a sudden load increase caused by for example a scene change and user focus. During such a load increase, the quality of service of the application having the user focus will decrease until the device detects the load increase. The device can reallocate resources to the application having the user focus after which the quality of service will increase again towards its previous level. However, the user may have noticed the quality decrease. In order to prevent this noticeable decrease of quality in overload situations, a method and a system are provided that guarantees a worst-case budget to the application having user focus and conditionally guarantees a budget surplus to an application not having the user focus. The latter application can then use that budget surplus to operate at a higher quality of service level.

Abstract: For a flexible consumer multimedia device that remains as robust and cost-effective as the current ones, media algorithms should become more flexible with respect to their resource requirements with the exchange in output quality. We call such algorithms scalable. The state of a cluster of scalable video algorithms (Job) in a consumer multimedia terminal can be described by three parameters. The first one is the job mode, that is the actual cluster of functions and their connections. The second one is the set of valid quality levels of the job mode, which is called operational set. The last one is the assigned quality level. The first two parameters supply the correct processing and the valid search space for the system optimization, and are selected by the job itself. The latter one reflects the actual resource allocation according to the available system resources and is selected by the QoS Resource Manager.

Abstract: Within the real-time processing domain, processing for example a video frame or audio can be divided into a number of tasks. Tasks receive budget (S102) for the resources it is allowed to use during processing. Since the processing performed by the tasks have timing constraints, a task must be able to determine its progress (S108). To enable a task to determine its progress the task refers to an amount of reference clock cycles it uses from a virtual reference clock and compares this amount to the number of sub-processing steps the task has performed. The virtual reference clock provides a plurality of reference clock cycles, wherein a reference clock cycle of the plurality of reference clock cycles is proportional to a ratio between the plurality of real-time clock cycles and the number of clock cycles comprised within the real-time budget.

Abstract: For an open and flexible system that is robust and cost-effective, it is proposed to use scalable video algorithms (106, 109, 110, 112, 113, 114, 306, 308, 406, 408). Scalable video algorithms (106, 109, 110, 112, 113, 114, 306, 308, 406, 408) can dynamically trade resource usage with visual output quality. In such a system both the visual output quality and the resource usage may change at run-time leading to unpredictable behaviour of the system. A novel approach that assists in the predictability of an open and flexible system is proposed. The idea is that by knowing the parameters that influence the output quality and load of some video algorithms (106, 109, 110, 112, 113, 114, 306, 308, 406, 408), by appropriately measuring them and by providing the necessary information (316, 320, 416, 420, 426, 427) to the system control (321, 421), the system control (321, 421) can react sooner and do the appropriate changes (317, 322, 323, 417, 422, 423), leading to a predictable system.

Abstract: Nowadays, programmable components (1304), rather than dedicated single-function components can perform continuous media processing in consumer devices, like digital television sets (1310), set-top boxes, PCs, or VCRs. The media processing algorithms that are written for those programmable components (1304), must be designed to provide a plurality of output quality levels in exchange for required processing resources. Since resources are finite, the media processing algorithms must be controlled in their resource usage and the output quality level they provide. Users of consumer devices do not like to see major changes in the quality of, for example, a video they are watching. Therefore, typical algorithm characteristics like the functions an algorithm comprises, the resource usage per function and the quality level per function are used to provide smoother quality transitions.

Abstract: In consumer devices, like digital television sets (610) or set-top boxes, there can be a problem with a sudden load increase caused by for example a scene change and user focus. During such a load increase, the quality of service of the application having the user focus will decrease until the device detects the load increase. The device can reallocate resources to the application (608) having the user focus after which the quality of service will increase again towards its previous level. However, the user may have noticed the quality decrease. In order to prevent this noticeable decrease of quality in overload situations, a method an a system (606) is provided that guarantees a worst-case budget to the application having user focus and conditionally guarantees a budget surplus to an application not having the user focus (610). The latter application can then use that budget surplus to operate at a higher quality of service level.

Abstract: Nowadays, programmable components (604), rather than dedicated single-function components can perform continuous media processing in consumer devices, like digital television sets (610), set-top boxes, PCs, or VCRs. The media processing algorithms that are written for those programmable components (604), must be designed to provide a plurality of output quality levels in exchange for required processing resources. Since resources are finite, the media processing algorithms must be controlled in their resource usage and the output quality level they provide. Users of consumer devices do not like to see major changes in the quality of, for example, a video they are watching. Therefore, typical algorithm characteristics like the functions an algorithm comprises, the resource usage per function and the quality level per function are used to provide smoother quality transitions.

Abstract: The method according to the invention detects a blocking task during a context switch performed by an underlying real-time operating system (406) and prevents the blocking task from running during the period in which the task blocked.

Abstract: The invention relates to a method of determining a best-case response time of a first periodic task, the method comprising a first step based upon Rate Monotonic Analysis of determining the priorities of the tasks that have to be scheduled on a system. In order to determine whether the set of tasks can be scheduled on the system, the best-case response time in addition to the worst-case response time is determined per task. This best-case response time is substantially equal to the difference between the start of a task with a lower priority (102) and the completion of this low priority task (104), the start being right after the release of the low priority task and the completion coinciding with the simultaneous release (104) all higher priority tasks.