Skip the navigation
Horizon Awards: 10 Cool Cutting Edge Technologies

Northwestern University and NEC Labs America's CRAMES: Power-Packed Memory



Sign up to receive Computerworld newsletters on your favorite technology topics


August 20, 2007 (Computerworld) -- Northwestern University and NEC Labs AmericaCRAMES Memory compression technique doubles storage in embedded systems, such as cell phones

Small mobile devices are inherently limited in the amount of memory they can carry, thereby restricting what applications they can run.

You will always have limited storage on mobile devices, because you want the device to be small and portable and very power-efficient, says Craig Mathias, principal at Farpoint Group, a wireless and mobile consultancy in Ashland, Mass., and a columnist. Memory compression can help in that regard, multiplying the efficiency of the storage you do have.

This summer, Tokyo-based NEC Corp. will release a new software memory compression technique called CRAMES (Compressed RAM for Embedded Systems) on its N904i cell phones. CRAMES more than doubles memory capacity while limiting power drain and performance loss to only 2.7%.

Wow Factor
Power-Packed Memory

Memory compression technique more than doubles usable storage in embedded systems, such as cell phones.

The companys research arm, NEC Laboratories America Inc., began researching compression technologies eight years ago. In 2004, lab consultant Haris Lekatsas and department head Srimat Chakradhar decided to explore integrating compression into the operating system. CRAMES was developed by Lei Yang, a doctoral student at Northwestern University, along with her academic adviser, assistant professor Robert P. Dick.

The idea was to transparently compress and decompress selected regions of memory to drastically reduce the memory footprint of embedded applications, says Dick. By carrying out online compression and decompression entirely in software, hardware platform redesign could be avoided.

Dick says researchers had previously tried compressing software but rejected that approach because it drained power and hurt performance. The Northwestern team aimed to find a way to run applications that required more memory, but without the drain.

To manage compressed memory, the development team decided to use the Linux kernels swapping mechanism to determine which pages should be compressed. Initially, they were able to reduce the drain to 10% using the established LZO compression algorithm. To further boost performance, the team developed a new compression algorithm called PBPM (Partial Based Partial Match). Other refinements include compressing data only when memory is low, modifying the memory management technology to reduce fragmentation and modifying the Linux kernel so it can eliminate defunct processes when necessary. Together, these steps held power drain and performance loss to 2.7%.

Embedded system designers and especially designers of cellular phones and [PDAs] need to pack more functionality on the devices every year to remain competitive, says Dick. CRAMES has allowed NEC to pack in more functionality without waiting for the next cycle of hardware design to catch up with the new increasing demands on memory.

Next cutting-edge technology >

Special Reports

Print this Story Send Us Feedback E-mail this Story Digg! Digg this Story Slashdot this Story

Special Reports

Meet Cobol's hard core fans
Oracle CEO Larry Ellison turns 70 with no retirement in sight
Sprint drops second shoe: $60 unlimited voice, text, data plan
More top stories...
Apple updates OS X Yosemite public beta
Opera Mini becomes default browser for Microsoft's fading feature phones
Small businesses seek to take off with the cloud

Ads by TechWords

See your link here

IT Jobs
Hot Topics
Special Report Topics
All Zones
The SAS Zone
Software Resource Center
Mobile Security
Disaster Recovery & Cost Savings
Strategic Content Management
Business Analytics Zone