Transfer Syntax Notation One (TSN.1)
A formal notation for describing messages in binary protocols
Features & Benefits
- Support flexible and custom message encoding.
- Handle messages that cannot be described by ASN.1.
- Handle all CSN.1 messages yet is more intuitive and more compiler friendly.
- Suitable for both standards based and proprietary messages.
- Enable software development tools to auto-generate message parsers.
- Independent of machine architecture and implementation language.
- Validated against many wireless standards including GSM/UMTS/LTE, CDMA2000, and WiMAX.
Introduction
Messages in binary protocols are often defined using ad hoc encodings. They are especially prevalent in bandwidth constrained systems such as wireless protocols where bit efficiency is important. These messages cannot be easily described using existing message description languages such as ASN.1, or in the case of CSN.1, the notation does not support message parser generation well.
Without a formal notation to capture this type of messages, they are often described informally using tables, illustrations, and plain English. This forces software engineers to implement the message parsing code by hand. Some standards define a large number of messages, many of which have complicated structures. Hand coding these parsers leads to long development cycles and error-prone code.
All that has changed with the introduction of the Transfer Syntax Notation One (TSN.1). The notation is designed specifically for messages that require flexible and custom encoding. TSN.1 enables system designers to define a message directly in terms of the actual bit sequence transmitted. In various literatures, this is often referred as the concrete or transfer syntax of a message. As demonstrated by our flagship product, TSN.1 Compiler (Pat. 7,818,732), software development tools can be used to automatically generate message parsers.
TSN.1 Examples
As illustrated in the following examples, message in many existing network communication standards can be naturally expressed in TSN.1. For a complete specification of TSN.1, please refer to the TSN.1 Specification document.
TCP/IP Header Formats
TCPHeader() ::=
{
SourcePort 16;
DestinationPort 16;
SequenceNumber 32;
AcknowledgementNumber 32;
HLen 4;
reserve 6;
// Code Bits
URG 1;
ACK 1;
PSH 1;
RST 1;
SYN 1;
FIN 1;
Window 16;
CheckSum 16;
UrgentPointer 16;
Options (HLen - 5) * 32;
}
IPHeader() ::=
{
Version 4;
HLen 4;
ServiceType 8;
TotalLength 16;
Identifcation 16;
Flags 3;
FragmentOffset 13;
TimeToLive 8;
Protocol 8;
HeaderCheckSum 16;
SourceIPAddress 32;
DestinationIPAddress 32;
Options (HLen - 5) * 32;
}
CDMA2000 1X
is2000_fdsch_HDM() ::=
{
USE_TIME 1;
ACTION_TIME 6;
HDM_SEQ 2;
SRCH_WIN_A 4;
T_ADD 6;
T_DROP 6;
T_COMP 4;
T_TDROP 4;
FRAME_OFFSET 4;
PRIVATE_LCM 1;
RESET_L2 1;
ENCRYPT_MODE 2;
FREQ_INCL 1;
if(FREQ_INCL == 1)
{
CDMA_FREQ 11;
}
PILOTS[] :
{
PILOT_PN 9;
PWR_COMB_IND 1;
CODE_CHAN 8;
}
}
CDMA2000 1xEV-DO
is856_rup_TrafficChannelAssignment() ::=
{
var N 4;
MessageSequence 8;
ChannelIncluded 1;
if(ChannelIncluded == 1)
{
Channel :
{
SystemType 8;
BandClass 5;
ChannelNumber 11;
}
}
FrameOffset 4;
DRCLength 2;
DRCChannelGain 6;
AckChannelGain 6;
NumPilots 4;
Pilots[NumPilots] :
{
PilotPN 9;
SofterHandoff 1;
MACIndex 6;
DRCCover 3;
RABLength 2;
RABOffset 3;
if(SofterHandoff == 0)
{
N = N + 1;
}
}
optional RELEASE_A :
{
MACIndexMSBsIncluded 1;
if(MACIndexMSBsIncluded == 1)
{
MACIndexMSBs[NumPilots] :
{
MACIndexMSB 1;
RAChannelGain 2;
}
DSCChannelGain 5;
DSC[N] 3;
}
}
}
GSM/UMTS/LTE
ts24008_AttachRequest() ::=
{
SkipIndicator 4 = 0x0; // 0000
ProtocolDiscriminator 4 = 0x8; // 1000
MessageType 8 = 0x1; // 00000001
MSNetworkCapability : ts24008_MSNetworkCapabilityIE;
CipheringKeySequence : ts24008_CipheringKeySequenceIE;
AttachType : ts24008_AttachTypeIE;
DRXParameter : ts24008_DRXParameterIE;
PTMSIorIMSI : ts24008_MobileIdentityIE;
OldRoutingAreaId : ts24008_RoutingAreaIdIE;
MSRadioAccessCapability : ts24008_MSRadioAccessCapabilityIE;
OptionalIES[] : // variable number of optional IEs
{
IEI_MSN 4; // IEI most significant nible
if(IEI_MSN == 9) // TMSI Status
{
reserve 3;
TMSIFlag 1;
}
else
{
IEI_LSN 4; // IEI least significant nible
IE : case (IEI_MSN 4 << | IEI_LSN) of
{
0x19 => OldPTMSISignature : ts24008_PTMSISignatureIE;
0x17 => RequestedReadyTimer : ts24008_GPRSTimerIE;
0x33 => PSLCSCapability : ts24008_PSLCSCapabilityIE;
_ => UnknownIE : ts24008_UnknownIE;
}
}
}
}
IEEE 802.11/WiFi
wifi_mac_CapabilityInformation() ::=
{
ESS 1;
IBSS 1;
CFPollable 1;
CFPollRequest 1;
Privacy 1;
ShortPreamble 1;
PBCC 1;
ChannelAgility 1;
reserve 2;
ShortSlotTime 1;
reserve 2;
DSSS_OFDM 1;
reserve 2;
}
IEEE 802.16/WiMAX
wimax_mac_ARQFeedbackIE() ::=
{
CID 16;
LAST 1;
ACKType 2;
BSN 11;
NumACKMaps 2;
if(ACKType != 1)
{
ACKMaps [ NumACKMaps + 1 ] : // Array of ACKMaps
{
if(ACKType != 3)
{
SelectiveACKMap 16;
}
else
{
SequenceFormat 1;
if(SequenceFormat == 0)
{
SequenceACKMap 2;
Sequence1Length 6;
Sequence2Length 6;
reserve 1;
}
else
{
SequenceACKMap 3;
Sequence1Length 4;
Sequence2Length 4;
Sequenc32Length 4;
}
}
}
}
if(LAST != 1)
{
Next : wimax_mac_ARQFeedbackIE; // Recursion
}
}