A second wave for WiMAX boosts appeal
01 November 2007
The WiMAX Forum has announced Wave 2, which is the way forward for mobile wireless technology. CAROLINE HAYES looks at how a British semiconductor company and one of the biggest names in test are preparing for telecomms’ next wave
At this year’s WiMAX World Europe Conference and Expo, British company PicoChip announced an industry-standard WiMAX basestation reference design with a software upgrade to support Mobile WiMAX Wave 2, the latest WiMAX standard version, and MIMO (multiple input, multiple output) which increases data rates.
The combination increases data throughput over a wider area. WiMAX Wave 2 delivers a maximum download rate of 40Mbit/sec and 12Mbit/sec maximum upload rate. It supports increased mobility for WiMAX, while data rates and reliability are increased with MIMO, which simultaneously sends and receives data using multiple antennae.
The reference design
The PC8532 WiMAX platform supports WiMAX Wave 2 and IO-MIMO and scales from femtocells, or access points, up to multi-sector carrier macrocells. Airspan uses the design’s programmable PHY to support IOT between systems running WiMAX forum Certified 16d, 16e SISO and 16e Wave 2 MIMO from a common hardware platform. The wireless broadband specialist’s customers in turn can deploy WiMAX services and migrate to the latest WiMAX features and performance enhancements as the specification evolves.
PicoChip’s PC8532 is used for WiMAX certification and the company claims that it has already demonstrated a range of interoperability with third party terminals. It supports Wave 2 and IO-MIMO in uplink and downlink. The 2x2 MIMO system in WiMAX is claimed to significantly reduce capex (capital expenditure) and opex (operating expenditure) for carriers, as the coverage and data rate are increased compared to other wireless technologies or to WiMAX without MIMO.
Customers are offered Wave 2 and MIMO as seamless upgrade, which should mean products are brought to market sooner. The company’s WiMAX reference design is at the core of the AT4, protocol conformance tester, the WiMAX Forum’s approved testing authority, sometimes referred to as the ‘golden modem’.
WiMAX test
Without the ability to test Wave 2 system profile, engineers will not be able to successfully deploy Mobile WiMAX products around the world. Already Mobile WiMAX as a technology is relevant throughout the globe and access to it is time-critical.
In response to the Wave 2 system profiles, Agilent has added MIMO and Wave 2 test support to three of its WiMAX measurement instruments, the Vector Signal Analyser (VSA), the Signal Studio and the Mobile WiMAX Test Set.
Standardised profiles specify options, such as MIMO, to make sure that Mobile WiMAX supports IEEE 802.16e-2005 and provides engineers with the current tools for signal analysis, signal generation and end-to-end functional test of Mobile WiMAX.
Test set
The E6651A Mobile WiMAX Test Set is described as a significant breakthrough in Mobile WiMAX testing as it can configure a range of network parameters through the Windows XP user interface. The integrated unit extends WiMAX test offerings from the company for development, verification and manufacturing.
It has flexible basestation emulation and IP traffic support. A distinguishing feature, Agilent claims it is a unique one, is that the test set can make on-board RF parametric measurements in a single, integrated unit. RF signal generation and signal analysis can be up to 6GHz and the test set includes a suite of high-speed, precision, accuracy RF measurements for characterisation, calibration and verification. At the moment, certification profiles 1A and 3A are supported, with others added as the WiMAX standards are formalised.
Interoperability
Other test solutions require external equipment to measure UL signals. Wave 2 enhancements to the test set include DL, STC, SM and UL collaborative MIMO measurement support. Protocols to support DUT operation in MIMO modes is also included.
The test set can be extended to enable protocol interoperability and application testing. The basestation emulation provides a controlled environment with the ability to configure a range of network parameters to test, stress and debug the protocol and data handling capabilities of a design. Thus, subscriber station designers and manufacturers can progress quickly from development to volume production, improve product integrity and quality and reduce cost.
For Mobile WiMAX radio PHY measurements, the test set provides OFDM constellation and EVM (BPSK, QPSK, 16QAM and 64QAM). It can measure error vector spectrum and error vector versus time, and also the complimentary cumulative distribution function and channel power, occupied bandwidth.
Application test
Key elements of MAC operation can be configured for test. Response time for Mobile WiMAX MAC can be tested as can the MAC management request message. Other tests include that of the dynamic service flow for given conditions and the test set can undertake initial ranging procedure verification under exception RF conditions.
The E6655A lab application provides convergence service network emulation to test the increasing number of features, complexity and software of emerging mobile devices. These have to be tested in a realistic network environment with support for realtime, end-to-end functional test of the WiMAX design. The E6655A allows engineers to run tests on a controlled network environment and not a lie network. The ability to run multiple applications can verify correct operation and stress-test the given WiMAX device.
Signal test
The 89601A VSA and the N7615B Signal Studio measurement instruments address the new test capabilities needed for Wave 2 system profiles. The VSA is a PC-based software package that measures RF and modulation quality of most digitally-modulated signals. It includes demodulators, filter, displays and analysis tools.
Both support PHY layer signal generation and analysis with specific capabilities such as matrix A and matrix B signals for downlink, uplink collaborative MIMO and creation of HARQ burst and uplink sounding zones.
Additionally, the N7615B Signal Studio provides MIMO fading embedded in a waveform. This means that engineers can test MIMO receivers without having to invest in fading hardware or software. N7615B Signal Studio software creates 802.16e waveforms for PHY layer testing and supports the ESG, MXG and PSG signal generators.
Other MIMO support from the company includes adding MIMO support to its Mobile WiMAX Wireless Library for use with its Advanced Design System (ADS) EDA software. There is support for STC/MIMO with two antenna sources and receivers for downlink and uplink, uplink collaborative MIMO source with one antenna, and STC/MIMO decoding in the STC/MIMO receivers. The updates also feature convolutional coding and convolutional turbo coding and decoding of the two with soft decision. There is also flexible configuration of ranging, fast feedback and HARQ-ACK channels in uplink source. New source coding and decoding models support convolutional turbo coding, such as SUI and Mobile WiMAX MIMO channel models, while ITU channel models support 2x2 MIMO.
www.agilent.co.uk
www.picochip.com
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