An Overview of Digital Trunked Radio: Technologies and Standards

AbstractLand Mobile Radio (LMR) refers to the two-way radio communication system that allows users sharing the same range of frequency to communicate with the others. LMR can be roughly classified into two main systems which are conventional and trunked radio systems. In conventional system, a frequency band is permanently dedicated to a voice channel. However, using trunked radio system can increase the spectrum efficiency by having pool of frequencies which are temporarily assigned to a group of users called talk group only when required. In trunked radio system, analog trunked radio is going to be obsolete since digital trunked radio offers better functions and features in terms of voice quality, security, spectrum efficiency and cost. Hence, the commercial applications focus on the digital one. There are many digital trunked radio technologies lunched in the market. However, in this paper, only Terrestrial Trunked Radio (TETRA), Project 25 (P25) and Digital Mobile Radio (DMR) are discussed and compared since they are developed and standardized by international standards organizations. Moreover, these technologies are chosen by many users/operators and mostly deployed in many regions across the world

Performance Analysis of Adaptive Location Update Schemes for Continuous Cell Zooming Algorithm in Wireless Networks

To reduce the transmitted power of base stations in mobile wireless networks, continuous cell zooming algorithm is a feasible dynamic cell zooming algorithm. In this algorithm, location management is required in order to know the locations of users. Movement-based Update is not compatible and the application of Convention Periodic Update (CPU) scheme in continuous cell zooming algorithm can lead to a high signaling cost. Thus, aiming to highlight the effectiveness of newly proposed location update schemes, Time-Adaptive Periodic Update (TAPU) and Location-Adaptive Periodic Update (LAPU), a simulation-based performance analysis is conducted. Applying in continuous cell zooming algorithm, the performances of TAPU and LAPU are compared to that of Convention Periodic Update (CPU) scheme in terms of transmitted power ratio, outage ratio and the number of update messages. The performances of TAPU and LAPU are analyzed in a network with different number of users and in a network with different average moving speeds of users. The results show that compared to CPU, both TAPU and LAPU have no significant effect on power saving capability of continuous cell zooming algorithm in every scenario. Meanwhile, LAPU and TAPU give a significant reduction of update messages in every scenario. In terms of QoS effect, LAPU gives approximately the same outage ratio as CPU and a higher outage ratio occurs in TAPU

An Overview of Cell Zooming Algorithms and Power Saving Capabilities in Wireless Networks

Cell zooming has emerged as a potential strategy to develop a green communication system in our society and it has become an essential research area of wireless communication. Aiming to highlight the trend of existing cell zooming algorithms and their power saving capabilities, this paper reviews a number of cell zooming algorithms that have been proposed in the literature. Static cell zooming algorithms are effective for off-peak hours and their maximum power saving capability is 50% since off-peak duration is typically not more than 12 hours.Meanwhile dynamic cell zooming algorithms are applicable in full-day operation and they are useful not only for power saving but also for load balancing. However, on/off switching delay, signalling overhead due to traffic information exchange and how to attain information of traffic spatial distribution are existing challenges in dynamic cell zooming algorithms. One noticeable point is that relative power saving in dynamic cell zooming algorithm is less than 50% if traffic spatial distribution is considered. Since location management (LM) was designed for effectively servicing to customers, further researches could lead to work on location management (LM) based cell zooming algorithms for both effective servicing and energy saving