Low Power WiMAX Chipsets Accelerate the Broad Adoption of WiMAX in Mobile Devices
By Haig Sarkissian, WiMAX20/20
Broad adoption of WiMAX networks and the fulfillment of the WiMAX "vision" greatly depend on the proliferation of WiMAX chipsets into battery operated mobile devices, including handsets, ultra mobile PCs and a variety of consumer electronic devices. One gating factor had been the power consumption of the WiMAX subsystem which puts a drain on batteries. The WiMAX chipset ecosystem has made great strides in this area. But have they met the "low power bar" necessary for wide adoption of WiMAX into mobile devices?
Trendsmedia, the organizers of the WiMAX World 2008 show, which took place in Chicago, USA on September 30 through October 2nd 2008 wanted to find out. WiMAX20/20, a leading WiMAX consultancy was recruited to organize the WiMAX Live - Low Power CPE Chipset Shootout. A first in the WiMAX industry, this session gave an opportunity to WiMAX chipset vendors to show live measurements of their low power solutions and explain how they are meeting the low power challenge. Among the merchant chipset vendors that were invited to the shootout were Altair, Beceem, Comsys, GCT, Intel, NextWave, Runcom, Sequans, and WaveSAT.
In order to establish a low power performance bar, the latest and most popular 3G handheld devices were surveyed to determine the battery life performance of these devices. Both EVDO and HSDPA based products were reviewed including the Palm Treo, Apple 3G iPhone, and the RIM Blackberry. A review of specifications concluded that "Talk Time" for these devices ranged between 4 hours and 6 hours. Similarly, Internet usage time averaged between 5 hours and 6 hours. WiMAX20/20 established two performance bars as follows:
Usage Mode Target Battery Life
Voice (VoIP) 6 hours of Talk Time (with 900mAh)
Data (Internet Usage, Video and Email) 6 hours of Data Usage (with 1300mAh)
A detailed Test and Measurement document was developed and was shared with the invitees. The document described the test conditions to which the participants were required to adhere and defined four tests that each participant must perform live in Chicago during WiMAX World 2008. The following were the four tests that were defined.
VoIP Traffic: The CPE/module is registered with the WiMAX network and is exchanging symmetrical DL/UL streams of 30Kbps of UDP packets, emulating a typical 20ms Low Bit Rate (LBR) codec. UDP DL: The CPE/module is registered with the WiMAX network and is engaged in a UDP download session of 5Mbps. UDP UL: The CPE/module is registered with the WiMAX network and is engaged in an UDP upload session of 2Mbps. Video Streaming: The CPE/module is registered with the WiMAX network and is receiving a constant bit rate stream of 384Kbps of UDP packets, emulating a typical QVGA H.264 video stream.
Two final participants took the challenge and joined the first WiMAX Live - Low Power CPE Chipset Shootout. These were GCT Semiconductor of San Jose, California and Altair Semiconductor of Israel.
The mood was tense at 9:00AM on Wednesday, October 1st in room 184d at the McCormick center where engineers and marketing professionals from Altair and GCT shook hands for the first time. A round table of 8 ft diameter had already been setup by Darcy Poulin of SiGe Semiconductor who would be performing the tests and refereeing the results. Agilent Technologies provided the necessary test equipment to measure the current consumptions of the devices under test. A vector signal analyzer was also provided by Agilent to confirm that the tests met the specified transmit power requirement. Engineers from Wintegra had provided the reference Wintegra/picoChip "Golden Base Station" to be used to connect the WiMAX modems and perform the testing. A professional video crew was retained by Trendsmedia to record the tests and produce a summary video which would be shared by a wider audience during a session titled "WiMAX Live - Low Power CPE Chipset Shootout" the next day.
Lights, Camera, Action
Randall Schwartz of WiMAX 20/20 officially welcomed the participants and thanked them for accepting the challenge and agreeing to test their devices in a live public forum at WiMAX World 2008. He reminded that the goal of the shootout was to show the WiMAX industry whether these chipsets have met the "low power bar" necessary for wide adoption of WiMAX into mobile devices. Participants were reminded about the 6 hour battery life performance bar that was set.
All Eyes on the Amp Meter
GCT engineers interconnected their device under test, a miniature USB WiMAX modem, through a mesh of attenuators and splitters which mimicked a MIMO antenna configuration and simulated signal loss between a base station and a subscriber unit. The network was connected to the Wintegra base station. The four tests were performed one by one and the current meter readings were recorded.
Altair engineers were next to test their SDIO WiMAX modem. The tests were repeated and the results were recorded.
The Test Results
In order to convert the current readings into battery life, it was assumed that a typical mobile device would consume 150mW in addition to the power consumed by the WiMAX modems measured in the tests. This would represent the power consumed by an application processor, display and memory. In addition, it was assumed that a 900mAh battery would be used for voice applications and 1300mAh battery would be used for data applications.
With these assumptions in place, the test results showed that the GCT Semiconductor solution beat the power savings bar established for voice operation of 6 hours. The solution delivered a battery life of 6.1 hours. For data usage, the GCT solution delivered an impressive 7+ hours of internet use, averaged over uploads, downloads and video streaming.
Usage Mode Target Battery Life GCT
Voice (VoIP) 6 hours of Talk Time 6.1 hours
Data (Internet) 6 hours of Data Usage 7+ hours
The Altair solution took advantage of advanced power saving techniques to deliver even more impressive results.
Usage Mode Target Battery Life Altair
Voice (VoIP) 6 hours of Talk Time 9.5 hours
Data (Internet) 6 hours of Data Usage 14+ hours
The data showed how much progress WiMAX device technology has made, even in the last year. Twelve months ago it was difficult to find a WiMAX solution that consumed less than one Watt. Here in a live demonstration, two different manufacturers, in two different configurations, showed low power performance in an unusual public demonstration. Both of these products could be incorporated into effective computing and voice handheld products with battery life performance equivalent to and beyond that offered in 3G wide-band wireless devices that are on the market today, while delivering broadband speeds.
Haig Sarkissian of WiMAX20/20 congratulated the participants for the impressive results that they had achieved and reminded the audience to look for ultra low power handsets and battery powered WiMAX products coming to the market in the next year.
