A dynamic TDMA system can utilize voice activity and allow the integration of voice and data traffic. This can be achieved by allocating frequency channels and time slots on demand. In this approach, upon the arrival ...
详细信息
A dynamic TDMA system can utilize voice activity and allow the integration of voice and data traffic. This can be achieved by allocating frequency channels and time slots on demand. In this approach, upon the arrival of a talkspurt or a data packet, the base station is requested to assign a time slot for each transmission. Message requests and assignments of mobile users are carried over a Control channel, while the voice and traffic are transmitted over a Traffic channel. Time slot assignments are made from a 'pool' of Traffic channels. A number of slots in the pool will be shared by voice and data, with voice having priority over data, and the remaining will be used by data only. Voice slots are reserved for the duration of the talkspurt whereas data packets are assigned on a per-slot basis. Data packets can be buffered whereas voice traffic can only tolerate limited delay beyond which talkspurts will be clipped off. The Control channel uplink access is based on Slotted Aloha so that mobile users have autonomous access to base stations. This paper presents the performance of the dynamic TDMA system outlined here. The analysis aims at assessing the capacity gained by using voice activity and voice/data integration, in terms of the impairments introduced to voice quality (e.g., speech clipping and/or delay) and the delays to data packets. The analysis has been based on a discrete time Markov model operating on a frame-by-frame basis that provides the joint distribution of the number of active voice and data users in the system. The analysis also evaluates the delays of message requests via the uplink control channel. In evaluating the clipping probability, we combine the impact of both the access delays at the control channel as well as the unavailability of time slots in the pool. Performance results indicate that the capacity gain may exceed 80% and the speech clipping can be kept below 1%. Also, data packets may be transmitted with limited delays even when all ca
Many object oriented methods have assumed class based approaches, without considering prototype based ones. Some authors, while admitting prototypes as a useful concept, only envision their application in early phases...
详细信息
An automated environmental stress testing system, designed and assembled for testing of high pin-count integrated circuit packages and surface mount solder joint reliability is described. Details are given of the soft...
详细信息
An automated environmental stress testing system, designed and assembled for testing of high pin-count integrated circuit packages and surface mount solder joint reliability is described. Details are given of the software and hardware used in the control of the environment chambers used, in monitoring of test specimen reliability parameters and in control and monitoring of special purpose integrated circuits for testing of IC package reliability. In addition, an automatic system for monitoring of the resistance of fine pitch surface mount solder joints and for detection and recording of thermally induced intermittent open circuits in these joints is described.
暂无评论