KEYWORDS: Lead, Control systems, Dynamical systems, Mobile communications, Network architectures, Telecommunications, Multimedia, Statistical analysis, Process control, Received signal strength
New approaches are presented to facilitate dynamic radio bandwidth management for mobile communication systems. The aim is achieve an overall high level of QoS for both handoff calls and new calls. At the same time, the utilization of wireless network resources, i.e. the revenues earned by the operator. The simultaneous satisfaction of these two conflicting interests, under varying mobility and network traffic conditions, will be difficult. However, a balanced operation could be obtained by applying two novel approaches in system management. First, apriori information about possible handoffs, in the form of cell transition probabilities could be provided by the mobile, which is based on data collected by the mobile itself. This information is used to make handoff reservation requests in neighboring cells. Second, simultaneously controlling the radio resource reservation and new call admission to the system. This approach controls both the amount of reserved channels and the number of new calls admitted in a dynamic way. A theoretical analysis and a simulation have been used to study these approaches and it has been demonstrated that these approaches perform better then other reported approaches in the literature.
KEYWORDS: Receivers, Internet, Software development, Local area networks, Algorithm development, Detection and tracking algorithms, Computer simulations, Microcontrollers, Networks, Computing systems
Special purpose hardware and application software have been developed to implement and test Voice over IP protocols. The hardware has interface units to which ISDN telephone sets can be connected. It has Ethernet and RS-232 interfaces for connections to LANs and controlling PCs. The software has modules which are specific to telephone operations and simulation activities. The simulator acts as a WAN environment, generating delays in delivering speech packets according to delay distribution specified. By using WAN simulator, different algorithms can be tested and their performances can be compared. The novel algorithm developed correlates silence periods with received voice packets and delays play out until confidence is established that a significant phrase or sentence is stored in the playout buffer. The performance of this approach has been found to be either superior or comparable to performances of existing algorithms tested. This new algorithm has the advantage that at least a complete phrase or sentence is played out, thereby increasing the intelligibility considerably. The penalty of having larger delays compared to published algorithms operating under bursty traffic conditions is compensated by higher quality of service offered. In the paper, details of developed system and obtained test results will be presented.
The basic concepts of temperature measurement in power transformers and underground power cables using fiber optic gratings are introduced. The economic benefits of continuous temperature measurements are discussed. The problems encountered in high density applications, i.e. using many sensors in the same power transformer, is identified as the resolution limitation due to comparatively large bandwidth of optical filters used. The deconvolution technique has been proposed as a possible solution to improve accuracy and resolution. The fundamental ideas are illustrated by giving results of a laboratory prototype using twelve measurement points. The prototype has a capacity to employ up to 30 gratings for each phase of a power transformer, connected to the same measuring unit using an optical multiplexer.
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