Answer:

• An embedded system is a computing system that forms an integral part of a larger system. It is the backbone of the larger system in that it performs a dedicated function on which the larger system depends.
• Embedded systems consist of a unique set of characteristics that define them.Each of these put forth a stipulated set of constraints/ metrics based on which an embedded system is designed.
• A designer, while designing an embedded system must make sure that these metrics are very well taken care of.The various challenges in meeting the two design metrics 1. Low Power and 2. High Performance are as follows:

1. Low Power - Power consumption is crucial to any embedded system.More the power consumed, more is the heat generated.This may result in a reduced battery life. Excessive temperatures may result in performance loss or even component failures. Taking this into account,cooling requirements of an IC has become a major design consideration of an embedded system. By minimizing the amount of power consumption, battery life of the system is maintained. Thus, heat dissipation and cooling requirements are the major challenges of this design metric.
2. High Performance - Performance is measured by the throughput of the system or the time required for its execution. Performance can be enhanced by reducing the execution time.For example- a digital camera that shoots a megapixel image in 0.5 seconds shows good performance.Thus, reducing the execution time of a system poses a challenge in this design metric.