Embedded, Everywhere A Research Agenda for Networked Systems of Embedded Computers (2001) / Chapter Skim
Currently Skimming:
2. Enabling Technologies
2. Enabling Technologies
Pages 39-75
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 39... ...
Because the scaling of silicon technology is a major driver of computing and communication, this chapter starts by reviewing silicon scaling and then looks at how computing and communication devices 39
|
From page 40... ...
Readers who are already well versed in these subject areas or who are more interested in understanding the systems-level issues that arise in EmNets should move on to Chapter 3. SILICON SCALING Much of the driving force for the technological changes seen in recent years comes from the invention of integrated circuit technology.
|
From page 41... ...
It is this rapidly decreasing cost curve that created and continues to expand a huge market for embedded computing, and as this same technology makes communication cheaper, it will allow the embedded computers to talk with each other and the outside world, driving the creation of EmNets. lust as electronic locks seem natural now (and soon it will be hard to imagine a world without them)
|
From page 42... ...
Growing Complexity Increasing processor performance has come at a cost, in terms of both the design complexity of the machines and the power required by the current designs (on the order of 10 to 100 W)
|
From page 43... ...
ENABLING TECHNOLOGIES 43 Simpler Processors Up to this point the focus has been on the highest performance processors, but technology scaling has also enabled much simpler processors to have more than sufficient performances Rather than adding complex2The words "simple" and "complex" are not used here as a shorthand reference to the Reduced Instruction Set Computing versus Complex Instruction Set Computing (RISC vs.
|
From page 44... ...
They refer to the complexity of a computer's microarchitecture and implementation, not its instruction set.
|
From page 45... ...
is a first-order constraint, requiring more expensive power supplies and more expensive cooling systems, making CPU packages more expensive; it may even affect the final form factor of the computer system.3 Power has always been constrained in embedded systems, because such systems typically cannot afford any of the remedies mentioned above. For example, the controller in a VCR cannot require a large power supply, cannot have a fan for cooling, and cannot make the VCR be taller than such products would otherwise be.
|
From page 46... ...
46 EMBEDDED, EVERYWHERE chine is inactive, a technique that is used in almost all portable systems, to careful power control of individual components on the chip. In addition, power is very strongly related to the performance of the circuit.
|
From page 47... ...
While processor-based solutions provide the greatest flexibility for application development, custom hardware is generally much more power efficient. Early work in low-power design by Brodersen et al.
|
From page 48... ...
48 10000 1000 100 10 Jan 1985 Jan 1988 Jan 1991 Jan 1994 FIGURE 2.2 Clock rate of various processors.
|
From page 49... ...
These changes in technology have also driven the cost of communication down for both wireline and wireless systems. The continued scaling of CMOS technology enables cheap signal processing and low-cost radio frequency circuits.
|
From page 50... ...
The evolution of the wireline infrastructure reflects both a historic emphasis on telephony as the principal application and the rise in data communications applications over the past few decades, a trend accelerated by the commercialization of the Internet in the l990s. Advances in technology and the entry of new providers of wireline services in competition with traditional telephone companies have combined to lower costs and prices of data communication, in turn stimulating yet more demand for it.
|
From page 51... ...
Optical fiber has become prominent in the network backbones, and its capacity has been multiplied by the advent of wavelength-division multiplexing, which exploits the ability to communicate through different colors in the optical spectrum and which was enabled by all-optical-fiber amplifiers. Together, these and other advances have lowered the cost per bit of transmission in the backbone and for the wireline infrastructure generally, although the connection from end users (especially residential or small business users)
|
From page 52... ...
52 EMBEDDED, EVERYWHERE Ethernet speeds have been improved from 10 to 100 Mbps and will continue to improve with new gigabit systems. Even in homes without any new wires, signal processing has allowed people to create a network on top of the old phone line infrastructure.
|
From page 53... ...
There are a multitude of new wireless technologies and accompanying standards that fill this space. For 10 to 30+ Mbps wireless communications, the 802.11b and 802.11a (sometimes known as wireless Ethernet)
|
From page 54... ...
satellite launched in the late 1950s, which had as its primary function an experiment on the use of solar cells for power supply. Owing to its small size and capability, it merely broadcast a continuous signal.
|
From page 55... ...
ERG COGS only principled Ways to claim a porUon of the spectrum but also how to reclaim it When needs change. Heterogeneity means that large EmNets ~1 re-he flop networks Mat ~1 forward data packets between devices mat have to exist in different parts of me spectrum (possibly as far apart as radio frequency (~)
|
From page 56... ...
56 EMBEDDED, EVERYWHERE Boxes 2.6 and 2.7 describe two areas where EmNets stress wireless communications in new ways. Both focus on short-range, low-power issues, in which there is more uncertainty and need for work than in the other more mature technologies.
|
From page 57... ...
ENABLING TECHNOLOGIES 57 GEOLOCATION In many electronic systems the geographic location of objects is not important; instead, it is the network topology, the relative position of objects within a network, that is important. Yet for many systems, geographic data can be very useful for example, to find the nearest printer
|
From page 59... ...
This would be useful when trying to ensure redundant coverage of a particular area, but needing only one node in the area to be powered on at any given point. Boxes 2.8 and 2.9 provide details of techniques that can assist in determining the location of nodes and, consequently, the larger network geometry (encompassing geographic location, coloration, and proximity information)
|
From page 60... ...
60 EMBEDDED, EVERYWHERE These latter systems have been very small in number compared with the more ad hoc designs (Lee, 2000~. Today, as described elsewhere in this report, embedded systems are becoming highly networked and are changing in fundamental ways.
|
From page 61... ...
In today's EmNets, the line between application and operating system often blurs, with reusable components such as communications protocols sometimes considered an operating system and sometimes an application and virtual machines considered neither a true operating system nor an application but rather a sort of middleware.
|
From page 62... ...
However, with hardware power increasing rapidly and available bandwidth increasing even more rapidly, new modes of connectivity (both wired and wireless) , richer user interfaces, and new standards such as lava, the functionality and resulting complexity are about to increase dramatically.
|
From page 63... ...
Boxes 2.11, 2.12, and 2.13 expand upon upgradability, high availability, and the ability to work with new hardware as additional ways in which software will need to be refined to handle the requirements of EmNets. An additional concern is the cost of correcting failures in EmNet software, which will often far exceed the corresponding cost in more traditional desktop and server environments.
|
From page 64... ...
These services could be provided by specialized hardware but in most cases will probably be provided by an operating system. However, as mentioned, traditional embedded system requirements do not disappear.
|
From page 65... ...
Feynman pointed out that tremendous improvements in speed and energy requirements, as well as in device quality and reliability, could be had if computing devices could be constructed at the atomic level. MEMS represent the first steps toward that vision, using the best implementation technology currently available: the same silicon fabrication that is used for integrated circuits.
|
From page 66... ...
Microfluidics is an emerging MEMS application in which the fluid capillaries and valves are all directly implemented on a silicon chip and controlled via onboard electronics. Still other MEMS devices implement a membrane with a tunneling current sensor for extremely precise measurements of pressure.
|
From page 67... ...
The aspects of silicon technology that yield the best electronics are not generally those that yield the best MEMS devices. As has been discussed, smaller is better for electronics.
|
From page 68... ...
SUMMARY This chapter has provided a brief overview of the core technologies that EmNets will use, the trends that are driving these technologies, and the research areas that will accelerate the widespread implementation of EmNets. It has argued that silicon scaling, advances in computing hardware, software, and wireless communications, and new connections to the physical world such as geolocation and MEMS will be the technological building blocks of this new class of large-scale system.
|
From page 69... ...
ERG COGS 69 computing' and actuating nodes. Me basic Rends are clear: These large' inexpensive' highly capable systems are becoming feasible because of We cumulative ejects of s1Ucon scaling as ever-smaller s1Ucon feature sizes become commerciaUy availed more and more transistors can be applied to a task ever more cheaply' thus bringing increasingly capable .
|
From page 73... ...
For instance, the potentially huge number of nodes, the ad hoc system extensions expected, the extended longevity, and the heavy reliance on wireless communications between nodes will collectively invalidate some basic assumptions built into today's network solutions. Increased needs for system dependability will accompany the use of EmNets for real-time monitoring and actuating, but existing software creation and verification techniques will not easily or automatically apply.
|
From page 74... ...
1997. "Low power signal processing architectures for network microsensors." Proceedings of the 1997 International Symposium on Low Power Electronics and Design, pp.
|
From page 75... ...
1998. "CMOS front end components for micropower RF wireless systems." Proceedings of the 1998 International Symposium on Low Power Electronics and Design.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.