List of UWB channels

Spectrum Definition

Many countries have allocated spectrum for UWB use, with various restrictions and power output limits. The standardized output level for UWB communications is –41.3dBm/MHz. The WiMedia Alliance has defined fourteen 500-MHz bands to divide up the 3.1-10.6 GHz spectrum allocated for Ultra-Wideband communications in the U.S. in 2002.

Many countries had already allocated some spectrum

Logical Channel Organization

Burst errors can occur in a single frequency due to RF noise. Therefore, interleaving symbols over three different UWB bands should minimize the total burst length in the message, improving the likelihood of error correction, thus improving the immunity of the signal. There is a slight time penalty for each frequency change because the PLL clocks have to settle at the new frequency.

Therefore, the WiMedia PHY Spec organizes the UWB Bands into Band Groups where a single logical channel can be defined that uses all three bands in the band group. Time Frequency Interleaving (TFI) channels spread their data across three frequency bands, while Fixed Frequency Interleaving (FFI) channels stay on a single frequency band during all time slots.

The two tables below are pulled directly from the WiMedia PHY Specification, v1.5. The Time Frequency Codes (TFC) define the frequency interleaving sequence for utilizing 1-3 of the bands within a band group. TFCs 1-4 are for TFI channels, TFCs 5-7 are for FFI channels, and TFCs 8-10 are for TFI2 channels, which simply interleave their data across two bands. Note that all TFCs will be in the same band at some time during their sequence.

TFC numbering of 1-10 repeats for each band group and these TFC numbers are primarily used by the MAC and PHY layers. However, a different numbering system is needed by higher layers to command the radio to switch to a unique logical channel across all of the UWB bands and band groups. This logical channel number is used by the application layers, such as the Wireless USB interface. As you can see from the table below, the FFI channels for BG1 and BG3 are 13-15 and 29-31, while the TFI channels for BG1 and BG3 are 9-12 and 25-28.

As an example, Japan allows usage of 7392-7920 MHz, which is Band9, the highest frequency band in Band Group 3. This corresponds to Channel 31, also known as BG3 TFC 7.

UWB Measurements and Calculations

In order to properly measure a UWB signal with a spectrum analyzer and compare it to the -41.3dBm/MHz, you should use the following settings. If you connect a UWB transmitter directly into a spectrum analyzer (conducted with a cable, no antenna over the air), you should get values in the -43dBm to -40dBm range.

• Detector: RMS (NOT Peak. Use Average if RMS is not available)
• Sweep: 1ms/point. (In the image, 601points on the screen, 601ms sweep, so 1ms/pt. This averages/integrates the power received over 1ms)
• RBW: 1 MHz
• VBW: 3 MHz

This SpecAn screenshot shows BG1 TFC5, channel 9. Note the three bands, with gaps in between.

If you are doing tests in an Anechoic or Semi-Anechoic chamber, you have to account for the conversion between dBm power in a 50ohm cable to dBuV/m electric field over the air, as well as the antenna and preamp gains and the long cable loss between the receiving chamber antenna and the spectrum analyzer. For an example calculation, see pages 13–15 of the TDK Test Report for FCC ID: YYJ-5390144, the "WUSB Host Radio Board".

Practical Considerations

Within a single band group, the maximum number of non-overlapping channels is actually three. Any time two devices are transmitting at the same frequency and within radio range (

References

References

1. [http://www.wimedia.org/en/specs.asp?id=specs WiMedia Alliance downloadable MAC and PHY specifications]
2. [http://www.miit.gov.cn/n11293472/n11293832/n12843926/13567589.html China official notice delaying DAA enforcement in BG1 to Dec 31st, 2013.] {{webarchive. link. (2012-11-27)
3. link. (2011-08-17)