UWBTracer

Wireless access in devices like cellular handsets and notebooks has helped generate wider interest in wireless capabilities for other consumer devices such as digital cameras, PDA's, portable digital media players and high-definition televisions (HDTVs).

Certified Wireless USB (WUSB) is a high-bandwidth wireless extension to the USB standard that is based on Ultra Wideband at the physical layer. It's designed to combine the speed and security of wired technology with the ease-of-use of wireless communications. WUSB provide 480 Mb/s throughput at distances up to 3 meters (10 feet) making it a compelling choice for adding wireless connectivity to today's digital media devices.

Protocol layer testing for wireless technologies generally involves a radio-based "sniffer" to eavesdrop on the exchange between devices. Analysis tools must perform this task with minimal impact on the real-world operating environment for the devices. LeCroy pioneered the early development of Bluetooth based analysis tools and leveraged this expertise to create a complete Wireless USB/UWB test system.

The developers of Wireless USB have strived to maintain a similar usage model and architecture as wired USB with a host-to-device connection. But unlike its wired predecessor, Wireless USB mandates more stringent attention to security to prevent snooping of wireless data traffic. These requirements are defined in the Certified Wireless USB Association Model Specification v1.0 and govern how devices will discover and establish secure connections. Part of this specification includes mandatory encryption of data packets transmitted over-the-air. This encryption can prevent analysis tools from eavesdropping on secure messages.

LeCroy's UWBTracer™ Protocol Analyzer provides an innovative solution to this security problem. For devices that use the cable association model, LeCroy offers an integrated plug-in for capturing the cable association sequence. Similar to a USB analyzer, this module transparently taps the wired link between host and device. It automatically records and passes the connection context to the radio-based analysis engine contained within the UWBTracer. The analyzer radio channel can then automatically follow the 4-way security handshake and derive the "session" key (or PTK). With this unique session key in the hardware recording engine, the analyzer can automatically decrypt the scrambled wireless traffic. For devices that use the Numeric Association model, LeCroy's UWBTracer provides a software interface for tracking the connection con-text manually between devices.

- In the cable association model, the UWBTracer Analyzer captures the connection context and then transfers this information to the radio module, where it is used to capture and decrypt radio traffic between host and device.

The association models in Certified Wireless USB are designed to deliver secure data transfers and ease-of-use to consumers. Efficient device-level validation requires that the analysis tool have a mechanism to capture and recall the connection context. LeCroy's UWBTracer system significantly improves test workflow by allowing over-the-air protocol monitoring to occur unencumbered by WUSB's security features.

Another key issue for early adopters in Ultra Wideband development is presented by the evolving state of the regulatory environment. Several regions including Europe and Japan have restricted UWB devices by requiring operation in specific channels and/or higher frequencies. Chipsets supporting higher band operation were not widely available in 2008 making investments in test equipment problematic for developers targeting world-wide deployments. Anticipating this issue, LeCroy designed the UWBTracer test system to allow users to quickly change the radio front end on the analyzer. This unique ability to evolve the test equipment to support future changes in the specifications allows test teams to protect their investment in UWB analysis tools and ultimately deliver highest quality products.

• WiMedia Alliance
• Wireless USB Promoter Group
• WiMedia Beaconing Protocol Test Considerations

The UWBTracer™ system is the industry's most advanced analysis tool for radio-based communications using WiMedia™ Alliance's Ultra Wideband (UWB) common radio platform and Certified Wireless USB protocol. Designed to verify functionality and interoperability between WiMedia devices, the UWBTracer non-intrusively records packets exchanged over-the-air and shows protocol events using the defacto standard CATC Trace display. It also provides capture of wire line MAC-PHY interface (MPI) traffic to assist early adopters integrating prototype UWB radio components.

Small, and portable, this flexible platform offers pluggable modules that allow users to upgrade the system in the field. This enables LeCroy to deliver the industry's first wireless analyzer that supports interchangeable RF modules from alternate PHY vendors. The ability to purchase additional radio modules allows users to upgrade the analyzer front end to support future changes in the UWB specifications or to optimize compatibility with their current test environment.

• Captures traffic between multiple Wireless USB endpoints within a WiMedia cluster
• Completely non-intrusive over-the-air recording
• Displays hierarchical views of WiMedia and Certified Wireless USB protocol using the CATC Trace™
• Interchangeable RF modules allow swapping of radio front ends to add support for future changes in the RF specifications
• Isolate specific areas of interest with real-time triggering on WiMedia frames and encrypted Wireless USB traffic
• Pre-capture filtering excludes non-essential and redundant packets from the trace to focus the analysis effort
• Disk spooling mode provides real-time time display of link and protocol activity
• Traffic Summaries automatically report error rates and protocol level metrics that are linked to trace level detail
• Solve MAC-PHY integration issues with simultaneous MPI tap and RF recording
• Full support for Certified Wireless USB security, including 4-way encryption handshake and USB cable association option
• Supports the latest WiMedia , Certified Wireless USB and WLP/WiNet Specifications

The UWBTracer features LeCroy's exclusive BusEngine technology which offers real-time triggering to pinpoint specific WiMedia events of interest. This hardware based recording engine is field upgradeable and provides an easy drag-and-drop interface for setting up multilevel triggering. There's full support for counters, timers and looping within the trigger logic. The analyzer can trigger on protocol errors like length mismatch, aborted frames or FCS errors.

UWBTracer allows on-the-fly pre-capture filtering to remove repetitive events like bus conditions or non-essential data frames. UWBTracer also makes it easy to filter in or out traffic transmitted on specific channels or sent from specific device addresses. Flexible post capture filtering can remove specific packets or individual fields from the display.

Comprehensive search is supported for all WiMedia and wireless USB layers. Additionally, the advanced search capabilities allow users to find specific combinations of protocol events using Boolean search functions.

The UWBTracer now supports spool-to-disk capture to allow extended recording sessions - for hours or even days. In spooled mode, captured traffic is shown in real-time. The ability to instantly view link status and beacon group occupancy in real-time makes debugging interoperability issues faster and more efficient. State changes can be observed - as they occur - without stopping and restarting the test. Signal strength (RSSI) and Link Quality (LQI) are displayed graphically and error events are also flagged in real-time.

The UWBTracer analyzer utilizes the CATC Trace™ display that is the industry's de facto standard for wired USB protocol analysis. The UWBTracer software shows packets time-synchronized in separate rows with every field labeled and color-coded. At the WiMedia Layer, it provides a chronological view of frames transmitted by devices. At the Wireless USB transfer layer, the software automatically groups the WiMedia frames that are part of a logical USB transaction and decodes the equivalents for USB Token, Data and Handshake packets.

The UWBTracer includes several graphical displays that show both timing and protocol information synchronized to trace level detail. These graphical views help users improve performance by making it easy to identify marginal timing conditions that may affect throughput.

The UWBTracer now offers full support for Certified Wireless USB Association Models. This includes the ability to derive the Pair-wise Temporal Keys (PTK) for each session by using the Connection Context to decode the 4-way handshake. This enables UWBTracer to record and trigger on decrypted secured traffic in real-time. Users can manually enter a Connection Context before or after recording the trace to decrypt scrambled data. For devices that utilize USB Cable Association, users can purchase an optional plug-in for capturing the Connection Context using a wired USB tap.

The CATC Trace software performs continuous error checking by automatically detecting potential violations at all layers of the protocol. The proper formation of each frame is checked for compliance to the specification, including validating FCS and HCS values. The actual USB channel time is compared to the CTA intervals to automatically verify channel efficiency and help ensure interoperability between wireless USB devices. For beacon frames, it provides full decoding of Distributed Reservation Protocol (DRP) and verifies that transmission timing adheres to DRP requests.

Only LeCroy's Protocol Solutions Group could anticipate and deliver the innovative features needed by early developers in this emerging wireless market. The UWBTracer's extensible design provides for future upgrades as the needs of early adopters change and this new communication standard matures. Beginning with the initial debug of the MAC-PHY communication path, to eventual interoperability testing between different WiMedia-based RF devices, the UWBTracer verification system is designed to reduce time-to-market for Certified WUSB chipsets, devices and software. LeCroy's leadership in designing innovative and reliable debug tools for the USB market make the UWBTracer the ideal choice both for migrating existing USB devices as well as developing new device categories using the WiMedia wireless interface.