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fixeria gerrit-no-reply at lists.osmocom.orgfixeria has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-gsm-manuals/+/22867 ) Change subject: TRXD: add initial proposal for TRXDv2 ...................................................................... TRXD: add initial proposal for TRXDv2 Change-Id: I03b2beeb535848b31fd629ba3cd330b43072c08b Related: SYS#4895, OS#4941, OS#4006 --- M common/chapters/trx_if.adoc 1 file changed, 217 insertions(+), 2 deletions(-) git pull ssh://gerrit.osmocom.org:29418/osmo-gsm-manuals refs/changes/67/22867/1 diff --git a/common/chapters/trx_if.adoc b/common/chapters/trx_if.adoc index d1aa566..c9d502e 100644 --- a/common/chapters/trx_if.adoc +++ b/common/chapters/trx_if.adoc @@ -18,6 +18,9 @@ The corresponding interface for every socket is at `P+100` on the BTS side. +NOTE: Starting from TRXDv2, it's possible to use only one socket for all +channels. See <<trx_if_pdu_batching>> for more details. + [[trx_if_clock_ind]] === Indications on the Master Clock Interface @@ -354,7 +357,7 @@ === TRXD protocol -PDUs on the data interface carry one radio burst per one UDP packet. +PDUs on the data interface carry one or multiple radio bursts per one UDP packet. Two kinds of TRXD PDU exist: * `TRX -> L1` (from transceiver to the L1): Uplink messages received from the MS, @@ -386,6 +389,11 @@ ** New field: MTS (Modulation and Training Sequence); ** New field: C/I (Carrier-to-interface) ratio; ** Downlink messages mostly unchanged. +* TRXDv2 (proposed in January 2021): +** Introduced the concept of burst batching (many bursts in one message); +** Changed the field ordering (facilitating aligned access); +** New field: batching indicator; +** New field: SCPIR for VAMOS. ==== Uplink Data Burst @@ -448,6 +456,47 @@ } ---- +.TRXDv2 Uplink message structure +[packetdiag] +---- +{ + colwidth = 32 + node_height = 40 + + 0-3: VER(2) + 4: RES + 5-7: TN + 8-15: MTS + 16: BATCH + 17-23: SPARE (0) + 24-31: RSSI + 32-47: TOA256 + 48-63: C/I + 64-95: FN + 96-127: Soft-bits +} +---- + +.TRXDv2 NOPE / IDLE indication message structure +[packetdiag] +---- +{ + colwidth = 32 + node_height = 40 + + 0-3: VER(2) + 4: RES + 5-7: TN + 8-15: MTS + 16: BATCH + 17-23: SPARE (0) + 24-31: RSSI + 32-47: TOA256 + 48-63: C/I + 64-95: FN +} +---- + VER: 4 bits:: TRXD header version, common for both `TRX -> L1` and `L1 -> TRX` directions. @@ -557,7 +606,7 @@ ==== Downlink Data Burst -.TRXD Downlink data burst message structure +.TRXDv0 and TRXDv1 Downlink data burst message structure [packetdiag] ---- { @@ -573,6 +622,45 @@ } ---- +.TRXDv2 Downlink data burst message structure +[packetdiag] +---- +{ + colwidth = 32 + node_height = 40 + + 0-3: VER + 4: RES + 5-7: TN + 8-15: MTS + 16: BATCH + 17-23: SPARE (0) + 24-31: PWR + 32-63: FN + 64-95: Hard-bits +} +---- + +.TRXDv2 Downlink data burst message structure for AQPSK +[packetdiag] +---- +{ + colwidth = 32 + node_height = 40 + + 0-3: VER + 4: RES + 5-7: TN + 8-15: MTS + 16: BATCH + 17-19: SPARE (0) + 20-23: SCPIR + 24-31: PWR + 32-63: FN + 64-95: Hard-bits for V0/V1 +} +---- + VER: 4 bits:: TRXD header version, common for both `TRX -> L1` and `L1 -> TRX` directions. @@ -583,6 +671,10 @@ Reserved, shall be 0. It can be used in the future to extend the TDMA TN range to (0..15), in case anybody would need to transfer UMTS bursts. +MTS: 8 bits (1 byte):: +Contains the Modulation and Training Sequence information. See <<coding-mts>> +for more information on the encoding. + FN: 32 bits (4 bytes):: GSM frame number, big endian. @@ -591,6 +683,129 @@ in dB. The absolute value is set on the control interface, so the resulting power is calculated as follows: `full_scale - (absolute_red + relative_red)`. +SCPIR: 4 bits:: +SCPIR (Subchannel Power Imbalance Ratio) - the ratio of power between Q and I +channels for a VAMOS pair. Value range: 0 .. 10. This field shall be present +when `MTC` field indicates the use of _AQPSK_ modulation. Otherwise all bits +shall be set to 0. + Hard-bits: 148 bytes for GSM, 444 bytes for EDGE:: Contains the downlink burst. Each hard-bit (1 or 0) of the burst is represented using one byte (0x01 or 0x00 respectively). + +Hard-bits for V0/V1: 148 bytes each, 296 bytes total:: +This field contains two sequences of hard-bits (148 bytes each) for an _AQPSK_ +moduleted burst (VAMOS mode). The two sequences are *not* interleaved: one +complete sequence for subscriber `V0` takes the first 148 bytes, then another +complete sequence for subscriber `V1` takes the subsequent 148 bytes. + +[[trx_if_pdu_batching]] +==== Burst batching + +Starting from TRXDv2, it's possible to combine several bursts into a single +PDU - this is called _burst batching_. The purpose of _burst batching_ is +to reduce socket load and eliminate possible PDU reordering, especially in +a multi-TRX setup. + +.TRXDv2 Uplink PDU structure (batched part) +[packetdiag] +---- +{ + colwidth = 32 + node_height = 40 + + 0-3: TRXNR + 4: RES + 5-7: TN + 8-15: MTS + 16: BATCH + 17-23: SPARE (0) + 24-31: RSSI + 32-47: TOA256 + 48-63: C/I + 64-95: Soft-bits +} +---- + +.TRXDv2 Downlink PDU structure (batched part) +[packetdiag] +---- +{ + colwidth = 32 + node_height = 40 + + 0-3: TRXNR + 4: RES + 5-7: TN + 8-15: MTS + 16: BATCH + 17-23: SPARE (0) + 24-31: PWR + 32-63: Hard-bits +} +---- + +TRXNR: 4 bits:: +Transceiver number (FIXME). + +BATCH: 1 bit:: +This bit indicates whether a batched burst follows. + +The ordering of bursts may be different with the only requirement that all +_batched_ bursts must belong to the same TDMA frame number indicated in the +first part. Thus the following combinations are possible: + +* a) one PDU contains bursts with the same TDMA timeslot number for all +transceivers (8 PDUs per a TDMA frame); +* one PDU contains complete TDMA frame with bursts for all 8 timeslots: +** b) either for a single transceiver (N PDUs per a TDMA frame), +** c) or for all transceivers (one PDU per a TDMA frame). + +.Example: batched PDU structure for a) +---- ++-------+----------------+----------------------------------+ +| TRX=0 | TDMA FN=F TN=T | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +| TRX=1 | TDMA FN=F TN=T | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +| TRX=2 | TDMA FN=F TN=T | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ++-------+----------------+----------------------------------+ +| TRX=N | TDMA FN=F TN=T | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +---- + +.Example: batched PDU structure for b) +---- ++-------+----------------+----------------------------------+ +| TRX=N | TDMA FN=F TN=0 | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +| TRX=N | TDMA FN=F TN=1 | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +| TRX=N | TDMA FN=F TN=2 | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ++-------+----------------+----------------------------------+ +| TRX=N | TDMA FN=F TN=7 | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +---- + +.Example: batched PDU structure for c) +---- ++-------+----------------+----------------------------------+ +| TRX=0 | TDMA FN=F TN=0 | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +| TRX=0 | TDMA FN=F TN=1 | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +| TRX=0 | TDMA FN=F TN=2 | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ++-------+----------------+----------------------------------+ +| TRX=N | TDMA FN=F TN=5 | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +| TRX=N | TDMA FN=F TN=6 | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +| TRX=N | TDMA FN=F TN=7 | Hard-/Soft-bits | ++-------+----------------+----------------------------------+ +---- -- To view, visit https://gerrit.osmocom.org/c/osmo-gsm-manuals/+/22867 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: osmo-gsm-manuals Gerrit-Branch: master Gerrit-Change-Id: I03b2beeb535848b31fd629ba3cd330b43072c08b Gerrit-Change-Number: 22867 Gerrit-PatchSet: 1 Gerrit-Owner: fixeria <vyanitskiy at sysmocom.de> Gerrit-MessageType: newchange -------------- next part -------------- An HTML attachment was scrubbed... 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