ABSTRACT
In recent years, mobile multimedia have become feasible and popular due to the rapid advances of semiconductor and portable diverse technology. Technology advances in video compression and transmission over wireless communication networks have enabled mobile multimedia on portable wireless devices, such as cellular phones, laptop computers connected to WLANs, and cameras in surveillance and environmental tracking systems. Video coding and streaming are also envisioned in an increasing number of applications in the areas of battlefield intelligence, reconnaissance, public security, and telemedicine. Present 3G and emerging 4G wireless systems and IEEE 802.11 WLAN/WMAN have dramatically increased transmission bandwidth and generated a great amount of users on video streaming applications. Althoughwireless video communications is highly desirable, a primary limitation inwireless systems is the basic design architecture that most mobile devices are typically powered by batteries with limited energy capacity. This limitation is of fundamental importance due to the high energy consumption rate in encoding and transmitting video bit streams during multimedia communications. Moreover, due to the relatively slow development of battery technologies, energy stored in a battery fitted in the
limited size of mobile devices cannot catch up with the power consumption of the super multimedia processor continuously developed in the pattern of Moore’s law. Thus, the gap between power consumption of the mobile multimedia application and the limited power source is becoming widened. Much work and research have been focused on energy-aware mobile multimedia communication and green computing of multimedia coding processes. Basically, there are three main directions of dealing with this problem. The first direction is to engage in hardware architecture improvement to optimize energy efficiency, which mainly depends on the technique and new design of microelectronics. Secondly, the nonlinear characteristics of different battery types, such as battery current effect, have been analyzed and adopted to achieve higher battery utilization. Piles of battery cells are operated to provide energy according to a dynamic sequence or pattern, which is called power management and scheduling. The third main direction looks into series of procedures applied to multimedia communication and wisely selects complexity control parameters in each procedure to secure the delivered quality and minimize energy consumption at the same time. It has been shown that achieving a satisfactory user experience needs a systematic consideration of both video source adaptation and network transmission adaptation, indicating that the core of mobile multimedia system design is how to achieve an ideal energy allocation balance between computation and communication. In other words, it depends on how to jointly select those computational complexity control parameters during video coding and transmission according to the real-time status and constraints, such as the video content characteristics, available network resources, underlying network conditions, battery capacity conditions, and distortion requirement.
