Welcome
We are very excited to announce this release of the XRA-31 system!
This version adds support for inverse upstream Concatenation and Fragmentation (ICCF) of 'Segment Header ON' service flows over multiple channels in real time. By this enhancement, users will not only see all the upstream DOCSIS bursts (segments), but also all the DOCSIS MAC frames will be directly available in the pcap output file, even if the packet was transmitted using multiple upstream channels (in which case the MAC frames were missing in earlier XRA-31 versions).
Furthermore this release has several stability and bug fixes.
Changelog 5.3-1671 (2022-06-20)
Enhancements
- [System] Inverse upstream Concatenation and Fragmentation (ICCF) of 'Segment Header ON' service flows over multiple channels in real time is now fully supported.
- [Wireshark] Upgraded on-system Wireshark version to v3.6.5.
Fixes
- [Firmware] Fixed data corruption issue on low-load upstream channels.
- [System] Fixed bug where 'null packets' are missing in the capture file.
- [System] Fixed bug where OFDMA data bursts are sometimes incorrectly timestamped.
- [API] Fixed issue where
xra31-capture
with additional output options is not functioning. - [GUI] Corrected interpretation of
docsIf31Cm(ts)DsOfdmChanPlcFreq
SNMP OIDs in help page.
Features
OFDM
- Real-time demodulation and decoding
- Full line rate
- 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
- PLC and NCP demodulation and decoding
- Including MER statistics
OFDMA
- Real-time demodulation and decoding
- Full line rate
- 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
- Real-time full line rate bandwidth request (REQ) message demodulation and decoding
- Initial Ranging and Fine Ranging demodulation and decoding
- Including MER statistics and time offset estimations
Downstream SC-QAM
- Real-time demodulation and decoding
- Full line rate
- Hardware timestamping of packets using reference 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 evenly 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
A-TDMA
- Real-time demodulation and decoding
- Full line rate
- 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
Known limitations
Firmware
-
OFDM
- Possible temporary data loss during dynamic NCP updates
- Zero-bit-loading of NCP subcarriers not supported
- No data MER statistics
-
OFDMA
- Unsupported pilot patterns: 5-7, 12-14
- No probing sequences
- No data MER statistics
-
A-TDMA
- 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
Known Issues
Firmware
- The first channel locking attempt of an OFDM or downstream SC-QAM channel after a system reset or a CMTS change can take considerably longer than subsequent locking attempts. This is because internal frequency offset has to be reliably estimated (after which it is cached).
System and services
- 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.
References
- [CM-SP-PHYv3.0] DOCSIS® 3.0 Physical Layer Specification (CableLabs®)
- [CM-SP-PHYv3.1] DOCSIS® 3.1 Physical Layer Specification (CableLabs®)
- [CM-SP-MULPIv3.1] DOCSIS® 3.1 MAC and Upper Layer Protocols Interface Specification (CableLabs®)
- [ITU-T Rec J.83] ITU-T J.83: Digital multi-programme systems for television, sound and data services for cable distribution (Telecommunication Standardization Sector of ITU)