Welcome
We are very excited to announce the third major release of the XRA-31 system!
The system can now capture upstream A-TDMA (full UCD type 29 and 35 support).
This means you can capture up to 1 OFDM channel, 1 OFDMA channel, 24 downstream SC-QAM and 8 A-TDMA channels simultaneously and synchronously with nanosecond resolution, as all packets are hardware timestamped using the same reference OFDM channel clock!
Furthermore this release has several new features, improvements and bug fixes.
Check out the details below.
Features
-
New since 3.0!
-
Upstream A-TDMA
-
Continuous upstream locking
- Added continuous synchronization of upstream channels with downstream channels.
- Added continuous automatic gain control adjustments for upstream channels.
-
WebAdmin (GUI) user experience improvements
- Better defaults and button locations to allow faster configuration editing.
- Where applicable, the status panel now also shows channel ID and frequency.
- Improved file system navigation.
-
OFDM
- Real-time demodulation and decoding
- Full line rate (up to approx. 2 Gbps per channel)
- Hardware timestamping of packets using channel clock (nanosecond resolution)
- All FFT sizes, cyclic prefixes and roll-off periods defined by [CM-SP-PHYv3.1]
- Data demodulation and decoding
- All interleaver settings defined by [CM-SP-PHYv3.1]
- All modulations from zero-bit-loading up to 4096-QAM defined by [CM-SP-PHYv3.1]
- All possible configurations of exclusion bands defined by [CM-SP-PHYv3.1]
- Multiple concurrent data profiles (from A up to P)
- Mixed-modulation profiles
- Dynamic data profile changes
- Timestamp precision of DOCSIS frames is equal to one OFDM symbol (between 21 and 45 microseconds depending on FFT size and cyclic prefix)
- PLC and NCP demodulation and decoding
- Including MER statistics
- Timestamp precision is on the order of a few nanoseconds
-
OFDMA
- Real-time demodulation and decoding
- Full line rate (up to approx. 1 Gbps per channel)
- Hardware timestamping of packets using reference OFDM channel clock (nanosecond resolution)
- All FFT sizes, cyclic prefixes and roll-off periods defined by [CM-SP-PHYv3.1]
- Dynamic UCD changes (including data profile IUC changes)
- Data demodulation and decoding
- All interleaver settings defined by [CM-SP-PHYv3.1]
- All modulations from zero-valued up to 4096-QAM defined by [CM-SP-PHYv3.1]
- All possible configurations of exclusion bands and unused sub-carriers defined by [CM-SP-PHYv3.1]
- All data profile IUCs defined by [CM-SP-MULPIv3.1] concurrently
- Supported pilot patterns: 1-4, 8-11
- Timestamp precision of DOCSIS frames is equal to one OFDMA frame (between 126 and 945 microseconds depending on OFDMA frame size)
- Real-time full line rate bandwidth request (REQ) message demodulation
- Timestamp precision is on the order of a few nanoseconds
- Initial Ranging and Fine Ranging demodulation and decoding
- Including MER statistics and time offset estimations
- Timestamp precision is on the order of a few nanoseconds
-
SC-QAM
- Real-time demodulation and decoding
- Full line rate (up to approx. 1.2 Gbps combined)
- 24 independent channels supported
- Hardware timestamping of packets using reference OFDM channel clock (nanosecond resolution)
- 64/256-QAM, independently configurable per channel
- Dynamically configurable annex
- Annex A (EuroDOCSIS)
- Annex B (US DOCSIS)
- All interleaving parameters (control words) defined in [ITU-T Rec. J.83] supported
- Viterbi decoding for increased reliability.
- Extended downstream frequency range support
- Channel frequencies can be any multiple of 62.5 kHz between 108 and 1006 MHz, complying with all CM requirements in [CM-SP-PHYv3.1].
- Two independent 248 MHz wide receive modules
- All channel frequency configurations that can be grouped into the two receive module bands are valid, e.g. a channel configuration consisting of three channels at 200 MHz, 440 MHz and 1000 MHz is valid, but a configuration with frequencies 200 MHz, 600 MHz and 1000 MHz is not.
- Data MER and Reed-Solomon decoder statistics
- Timestamp precision of DOCSIS frames is equal to one MPEG frame (between 29 and 56 microseconds depending on annex and modulation)
-
A-TDMA
- Real-time demodulation and decoding
- Full line rate (up to approx. 240 Mbps combined)
- 8 independent channels supported
- Hardware timestamping of packets using reference OFDM channel clock (nanosecond resolution)
- Full A-TDMA UCD type 29 and 35 support (with the sole exceptions of differential encoding, zero-length preambles and IUC 2 Request_2 demodulation).
- All channel bandwidths (from 200 kHz to 6.4 MHz) defined in [CM-SP-PHYv3.0]
- All upstream center frequencies allowed by [CM-SP-PHYv3.0]
- All modulation types (from QPSK to 64-QAM) defined in [CM-SP-PHYv3.0]
- All preamble patterns, types (QPSK0/QSPK1) and lengths from 2 to 1536 bits defined in [CM-SP-PHYv3.0] (Hence, the minimum allowed preamble length is one QPSK symbol)
- Scrambler on/off
- Fixed/shortened last codeword
- All interleaving parameters allowed by [CM-SP-PHYv3.0]
- All Reed-Solomon FEC parameters allowed by [CM-SP-PHYv3.0]
- Supported IUCs: 1 (Request), 3 (Initial Maintenance), 4 (Station Maintenance), 5 (Short Data Grant), 6 (Long Data Grant), 9 (Advanced PHY Short Data Grant), 10 (Long PHY Short Data Grant), 11 (Advanced PHY Unsollicited Grant)
- Dynamic UCD changes
- Detailed statistics per demodulated burst
- Data MER
- Time offset
- Reed-Solomon decoder statistics
- Start minislot ID
References
- [CM-SP-PHYv3.0] DOCSIS 3.0 Physical Layer Specification (version I13 or later; http://www.cablelabs.com/specs/)
- [CM-SP-PHYv3.1] DOCSIS 3.1 Physical Layer Specification (version I13 or later; http://www.cablelabs.com/specs/)
- [CM-SP-MULPIv3.1] DOCSIS 3.1 MAC and Upper Layer Protocols Interface Specification (version I14 or later; http://www.cablelabs.com/specs/)
- [ITU-T Rec J.83] ITU-T J.83: Digital multi-programme systems for television, sound and data services for cable distribution (December 2007, Telecommunication Standardization Sector of ITU)
Known limitations
Firmware
-
OFDM
- Limited to one supported channel receiver
- Possible temporary data loss during dynamic NCP updates
- Zero-bit-loading of NCP subcarriers not supported
- No data MER statistics
-
OFDMA
- Limited to one supported channel receiver
- Unsupported pilot patterns: 5-7, 12-14
- No probing sequences
- No data MER statistics
-
SC-QAM
- Limited to 24 supported channel receivers
-
A-TDMA
- Limited to 8 supported channel receivers
- UCD type 2 (DOCSIS 1.x PHY channel and mixed DOCSIS 1.x/2.0 TDMA PHY channel) channels not supported
- Differential encoding not supported
- Zero preamble length not supported
- IUC 2 (Request_2) not supported
Environment and system tools
xra31-admin: It is not possible to follow the system/service logs
Analysis
- Captured packets are not ordered by timestamp
Changelog 3.0.2-944 (2019-08-08)
Improvements
-
System and services
- Better thermal management.
- XRA-31 temperature sensor information is now available via standard Linux Hardware Monitoring interface; User-space application: sensors
- FPGA will be shut down when we cannot ensure correct behavior (especially regarding timing)
- Device Driver: Add FPGA firmware and state checks.
- FPGA firmware and driver version check, feature verification; using FPGA feature level.
- Device state verification: Do not allow to access the device when it has been shut down or restarted.
- General: Improved FPGA firmware and driver version and feature verification.
- Control Daemon: Improved exception handling to avoid improper exit due to FPGA thermal shutdown (or restart).
- Avoid or remove unnecessary mutex locks.
- Control Daemon: Improved logging.
- Decreased debug logging.
- Rate limit on error logging.
- Control Daemon: small speed-up when configuring downstream SC-QAM channels.
- Control Daemon: Avoid inconsistent processing state: No longer allow to configure more than one Upstream Channel Receiver with the same US Channel ID.
- Firmware tool: Better exception handling related to device driver / firmware control.
- XRA-31 self-test: Better exception handling related to device driver / firmware control.
Bugfixes
-
Firmware
-
General
- Fixed suboptimal placement of PCIe clock manager.
- Fixed several unsafe clock domain crossings.
- Fixed several place-and-route warnings.
-
OFDM
- Fixed bugs in MMM processor where packets were incorrectly dropped if a codeword contains 3 info bytes or if the MAC header is fragmented over multiple codewords.
- Fixed bug in codeword builder which led to packet loss in case a NULL NCP-MB is the only data NCP-MB in an OFDM symbol.
-
SC-QAM
- Fixed improper reset of hardware blocks after disabling downstream SC-QAM channel receiver. This reduces power consumption considerably.
- Fixed spurious output valid signal of deinterleaver after reset or FEC frame sync loss.
-
Systems and services
- Fix XRA TLV length of IUC for ranging packets in pcap output files (
xra.tlv.iuc field in Wireshark).
- Fixed possible multi-thread access issues with pcap file save.
- Fix reset of US Channel ID/SID mapping state for all upstreams when the configuration of a single upstream channel receiver changed.
- Device driver: Fixed possibly uninitialized DMA registers.
-
WebAdmin (GUI)
- Fixed incorrect display of OFDMA frequency range.
Known Issues
-
Firmware
-
General
- After a system (re)boot, e.g. as part of a system update, it's possible that the inter-FPGA serial links are stuck in a non-operational state. This is signaled in the GUI by error messages on connector US-1. We have taken several measures to improve resilience against this behavior, but are still working on a more pertinent solution. In the meantime, please reset the system via the GUI system page until the serial links are fully operational.
-
OFDM
- The first channel locking step after a system reset or a CMTS change can take considerably longer than subsequent locking steps. This is because internal frequency offset has to be reliably estimated (after which it is cached).
This effect is considerable on small-bandwidth OFDM channels. Depending on PLC frequency and FFT size, initial locking of a 24 MHz channel (the minimum allowed per [CM-SP-PHYv3.1]) can take up to 10 minutes. Subsequent re-locking steps, even on different channels, should be on the order of seconds. A workaround is to first 'pre-lock' the XRA-31 on a dummy 192 MHz channel (which should take no longer than 1 minute), remove this channel and re-add the 24 MHz channel.
-
System and services
- The system accepts file names longer than 255 characters and starts capturing, but storing the file fails in this case.
- The reported upstream channel MER is the average over all fine ranging requests (for OFDMA) or all data bursts excluding initial ranging requests and bandwidth requests (for A-TDMA) over an elapsed interval of at most 30s. As such, it is possible that N/A (not available) is shown on low-load channels with T4 timeout multiplier higher than 1.
- Captured Wireshark traces might contain invalid (malformed) packets corresponding to collisions (or possible RF interference) on A-TDMA IUC 1 (bandwidth request) grants. In a future release we plan to filter out these spurious bursts.
- Inverse upstream Concatenation and Fragmentation (ICCF) of "segment header on" service flows is now performed for each channel independently. Hence, for CMs in MTCM (multi transmit channel mode), MAC frames that are fragmented over multiple upstream channels are not detected and consequently absent in the Wireshark trace. A future release will support ICCF over multiple channels.
-
WebAdmin (GUI)
- Once a support archive is created, the UI framework sometimes start creating multiple archives in a loop. Other system tasks (for example system reset) might take a long time until they are performed.
As a workaround the user can use the power button on the system to restart the system. Press once shortly to start shutting down the system properly. Once shut down, press the power button again to start the system again.
- Layout on small displays can be improved.
Changelog 3.0-795 (2019-06-11)
Improvements
-
Firmware
-
OFDM
- Channel receivers are now disabled on FPGA after removal of the corresponding OFDM(A) channels, which reduces power consumption considerably. This has no considerable impact on subsequent locking time.
- Dynamic NCP updates are now supported but might still lead to temporary data loss.
-
OFDMA
- Channel receivers are now disabled on FPGA after removal of the corresponding OFDM(A) channels, which reduces power consumption considerably. This has no considerable impact on subsequent locking time.
-
SC-QAM
- Improved channel equalization of EuroDOCSIS (annex A) SC-QAM channels.
-
A-TDMA
- Added upstream A-TDMA support
-
System and services
- Time and power offset of all locked upstream channels (including OFDMA) is now continuously tracked and updated. This ensures that the XRA-31 dynamically adapts to RF network changes or drift over long time periods. Note that the internal time offset corrections are rather conservative, allowing reliable troubleshooting of time offset CM/CMTS issues via the Wireshark XRA header of upstream data bursts.
- More efficient processing of highly-loaded OFDM profiles with high fraction of uncorrectables.
- Better handling of upstream segments which only contain stuff bytes.
- The XRA-31 Control Daemon no longer exits when the FPGA firmware is not supported.
- The Control Daemon no longer allows to change the configuration (enter full access mode) if hardware errors have been detected.
- IUC is now also included in the XRA header of OFDMA initial and fine ranging packets. This allows easier filtering.
-
WebAdmin (GUI)
- Reviewed Channel configuration
- US/EURO slider (for changing downstream SC-QAM annex) is moved to edit mode of the downstream channels.
- Downstream SC-QAM channels now use 256-QAM by default instead of 64-QAM.
- You can now sort on the channel name.
- The upstream (OFDMA/A-TDMA) add-button is also disabled when there are no more detected upstream channels available.
- Status information
- XRA-31 self-test errors are now shown as system errors on the Connectors.
- The GUI properly reports invalid firmware state to the user via the Connector state. This can happen for example when an update of the firmware has failed.
- Rounding start/stop frequencies for OFDM(A) channels to MHz boundary if possible.
- Where applicable, channel ID and frequency are also shown in channel name.
- Capture stop reason is now also shown in the Capture status information.
- Replaced confusing '-' separator in expanded view. Now using a dot-symbol to avoid incorrectly interpreting the values as negative values.
- System page
- Added confirmation window before resetting the system.
- Do not allow to create multiple support archives at once.
- All system administration related tasks show a notice and/or are disabled when a support archive is being created. The latter can take a long time and since the system administration tasks are run sequentially, the user might be waiting for a long time without any notification otherwise.
- File system navigation
- Added missing leading '/' when showing absolute file system paths on the server.
- Added "select all" / "select none" button.
- Add "directory up" links where file system navigation is possible.
- Files are ordered by date by default.
-
Wireshark
Bugfixes
-
Firmware
- Declare OFDMA channel as unlocked after lock on downstream reference clock is lost.
-
System and services
- Fixed several bugs related to incorrect timestamps of captured downstream SC-QAM packets in case no OFDM channel is present.
- Fixed invalid creation of non-existing upstream Channel ID 0 and/or 255 in certain situations.
- Fixed segmentation fault occurring in rare circumstances.
- Fixed recovery when MAC stream loses lock.
- Fixed race condition in OCD processing.
- Fixed incorrect reporting of "Reed-Solomon Decoding Successful" (
xra.tlv.cw_info.rs_decoding_successful) in XRA header in capture file.
-
WebAdmin (GUI)
- Fixed issue where WebAdmin tries to add multiple filters and/or file outputs to a Capture.
- Fixed issues with multi-user access.
- Fixed some graphical issues when scaling the UI.
- Fixed issue deleting files with ',' in their name.
Known Issues
-
Firmware
-
General
- After a system (re)boot, e.g. as part of a system update, it's possible that the inter-FPGA serial links are stuck in a non-operational state. This is signaled in the GUI by error messages on connector US-1. We have taken several measures to improve resilience against this behavior, but are still working on a more pertinent solution.
In the meantime, please reset the system via the GUI system page until the serial links are fully operational.
-
OFDM
- The first channel locking step after a system reset or a CMTS change can take considerably longer than subsequent locking steps. This is because internal frequency offset has to be reliably estimated (after which it is cached).
This effect is considerable on small-bandwidth OFDM channels. Depending on PLC frequency and FFT size, initial locking of a 24 MHz channel (the minimum allowed per [CM-SP-PHYv3.1]) can take up to 10 minutes. Subsequent re-locking steps, even on different channels, should be on the order of seconds. A workaround is to first 'pre-lock' the XRA-31 on a dummy 192 MHz channel (which should take no longer than 1 minute), remove this channel and re-add the 24 MHz channel.
-
System and services
- The system accepts file names longer than 255 characters and starts capturing, but storing the file fails in this case.
- The reported upstream channel MER is the average over all fine ranging requests (for OFDMA) or all data bursts excluding initial ranging requests and bandwidth requests (for A-TDMA) over an elapsed interval of at most 30s. As such, it is possible that N/A (not available) is shown on low-load channels with T4 timeout multiplier higher than 1.
- Captured Wireshark traces might contain invalid (malformed) packets corresponding to collisions (or possible RF interference) on A-TDMA IUC 1 (bandwidth request) grants. In a future release we plan to filter out these spurious bursts.
- Inverse upstream Concatenation and Fragmentation (ICCF) of "segment header on" service flows is now performed for each channel independently. Hence, for CMs in MTCM (multi transmit channel mode), MAC frames that are fragmented over multiple upstream channels are not detected and consequently absent in the Wireshark trace. A future release will support ICCF over multiple channels.
-
WebAdmin (GUI)
- Once a support archive is created, the UI framework sometimes start creating multiple archives in a loop. Other system tasks (for example system reset) might take a long time until they are performed.
As a workaround the user can use the power button on the system to restart the system. Press once shortly to start shutting down the system properly. Once shut down, press the power button again to start the system again.
- Layout on small displays can be improved.
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