eCPRI Specification V2.0 (2019-05-10)
Interface Specification
Common Public Radio Interface:
eCPRI Interface Specification
The eCPRI specification has been developed by Ericsson AB, Huawei Technologies Co. Ltd, NEC Corporation and Nokia (the “Parties”) and may
be updated from time to time. Further information about eCPRI, and the latest specification, may be found at http://www.cpri.info
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© 2019 Ericsson AB, Huawei Technologies Co. Ltd, NEC Corporation and Nokia.
CPRI
eCPRI Specification V2.0 (2019-05-10)
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Table of Contents
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1. Introduction ................................................................................................................. 4
2
2. System Description .................................................................................................... 6
3
2.1. Definitions/Nomenclature ............................................................................. 6
4
2.2. System Architecture ..................................................................................... 8
5
2.3. Functional Description ................................................................................. 9
6
2.3.1. Functional Decomposition ............................................................... 10
7
3. Interface Specification .............................................................................................. 11
8
3.1. Protocol Overview ....................................................................................... 11
9
3.1.1. Physical Layer ................................................................................. 13
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3.2. User Plane ................................................................................................... 13
11
3.2.1. User Plane over Ethernet ................................................................ 13
12
3.2.2. User Plane over IP .......................................................................... 14
13
3.2.3. eCPRI Message Format .................................................................. 14
14
3.2.3.1. eCPRI Transmission Byte Order ............................... 15
15
3.2.3.2. Common Header ...................................................... 15
16
3.2.3.3. eCPRI Payload ......................................................... 16
17
3.2.3.4. Mapping Examples ................................................... 16
18
3.2.4. Message Types ............................................................................... 17
19
3.2.4.1. Message Type #0: IQ Data ....................................... 17
20
3.2.4.2. Message Type #1: Bit Sequence .............................. 19
21
3.2.4.3. Message Type #2: Real-Time Control Data .............. 21
22
3.2.4.4. Message Type #3: Generic Data Transfer ................ 22
23
3.2.4.5. Message Type #4: Remote Memory Access ............. 24
24
3.2.4.6. Message Type #5: One-Way Delay Measurement .... 28
25
3.2.4.7. Message Type #6: Remote Reset ............................. 34
26
3.2.4.8. Message Type #7: Event Indication .......................... 36
27
3.2.4.9. Message Type #8: IWF Start-Up ............................... 41
28
3.2.4.10. Message Type #9: IWF Operation ............................ 43
29
3.2.4.11. Message Type #10: IWF Mapping ............................ 51
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3.2.4.12. Message Type #11: IWF Delay Control .................... 56
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3.2.4.13. Message Type #12 - #63: Reserved ......................... 57
32
3.2.4.14. Message Type #64 - #255: Vendor Specific .............. 57
33
3.3. C&M Plane ................................................................................................... 57
34
3.4. Synchronization Plane ................................................................................ 58
35
3.5. QoS .............................................................................................................. 58
36
3.5.1. VLAN Tagging for Ethernet-switched fronthaul networks ................. 58
37
3.5.2. QoS for IP-routed fronthaul networks .............................................. 58
38
4. Forward and Backward Compatibility ..................................................................... 59
39
4.1. Fixing eCPRI Protocol Revision Position .................................................. 59
40
4.2. Reserved Bits and Value Ranges within eCPRI ........................................ 59
41
4.3. eCPRI specification release version .......................................................... 59
42
4.4. Specification release version mapping to eCPRI protocol revision ........ 59
43
5. Compliance ............................................................................................................... 61
44
6. Annex A - Supplementary Specification Details (Informative) .............................. 62
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6.1. Functional Decomposition ......................................................................... 62
46
6.1.1. eCPRI Functional Decomposition .................................................... 62
47
6.1.2. Bit Rate Calculations / Estimations .................................................. 64
48
6.1.2.1. Bit Rate Calculation Example.................................... 64
49
6.2. Synchronization and Timing ...................................................................... 65
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eCPRI Specification V2.0 (2019-05-10)
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6.2.1. Synchronization of eRE ................................................................... 65
1
6.2.2. Synchronization of eREC................................................................. 65
2
6.2.3. Synchronization of IWFs .................................................................. 65
3
6.3. Link Delay Management ............................................................................. 65
4
6.3.1. Reference Points for Delay Measurement ....................................... 66
5
6.3.2. Delay Management example ........................................................... 70
6
6.4. Network Connection Maintenance ............................................................. 72
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6.5. Networking .................................................................................................. 73
8
6.5.1. Difference between eCPRI and CPRI .............................................. 73
9
6.5.2. eCPRI/CPRI networking with eCPRI/CPRI IWF type 0 .................... 74
10
6.5.3. eCPRI/CPRI networking with eCPRI/CPRI IWF type 1 and type 2 ... 75
11
6.6. Priority considerations ............................................................................... 76
12
6.7. Message Ordering Considerations ............................................................ 76
13
6.8. Security ........................................................................................................ 77
14
6.8.1. eCPRI Network Security Protocol .................................................... 77
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6.8.2. eCPRI Network Security Specification ............................................. 77
16
6.8.2.1. User plane ................................................................ 77
17
6.8.2.2. C&M plane ................................................................ 77
18
6.8.2.3. Synchronization plane............................................... 77
19
7. Annex B – eCPRI/CPRI Interworking with IWF type 0 (Informative) ...................... 78
20
7.1. Concept ....................................................................................................... 80
21
7.2. Bridging of User Plane ................................................................................ 81
22
7.3. Bridging/Routing of C&M Plane ................................................................. 82
23
7.4. Bridging of Synchronization Plane ............................................................ 83
24
7.5. Bridging of L1 inband protocol .................................................................. 83
25
7.6. Start-up Sequence ...................................................................................... 84
26
8. Annex C – eCPRI/CPRI Interworking with IWF type 1 and type 2 .......................... 85
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8.1. Concept ....................................................................................................... 85
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8.2. Definition of IWF type 1 and IWF type 2 CPRI ports ................................. 85
29
8.3. Bridging of User Plane ................................................................................ 86
30
8.4. Bridging/Routing of CPRI Control Words .................................................. 86
31
8.5. Bridging of Synchronization Plane ............................................................ 86
32
8.6. Bridging/handling of CPRI sub-channels 0 and 2 ..................................... 87
33
8.7. Start-up Sequence ...................................................................................... 87
34
8.7.1. eCPRI/CPRI IWF Start-up sequence overview ................................ 87
35
8.7.2. Start-up Delay Management ............................................................ 88
36
8.7.3. IWF CPRI port start-up sequence .................................................... 90
37
8.7.3.1. General ..................................................................... 90
38
8.7.3.2. Layer 1 Start-up Timer .............................................. 90
39
8.7.3.3. State Description ...................................................... 91
40
8.7.3.4. Transition Description ............................................... 95
41
8.8. Synchronization .......................................................................................... 97
42
8.9. Delay Management ...................................................................................... 97
43
8.10. Handling of eCPRI Remote Reset and CPRI Reset ................................. 100
44
8.11. Link and Fault Management ..................................................................... 100
45
8.11.1. IWF CPRI transmitter fault recovery/actions for CPRI detected
46
faults ............................................................................................. 102
47
8.11.2. IWF CPRI transmitter fault recovery/actions for Ethernet detected
48
faults ............................................................................................. 102
49
9. List of Abbreviations .............................................................................................. 104
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10. References .............................................................................................................. 107
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11. History ..................................................................................................................... 108
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eCPRI Specification V2.0 (2019-05-10)
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1. Introduction
1
The Common Public Radio Interface (CPRI) is an industry cooperation aimed at defining publicly available
2
specifications for the key internal interface of radio base stations, such as eCPRI connecting the eCPRI
3
Radio Equipment Control (eREC) and the eCPRI Radio Equipment (eRE) via a so-called fronthaul transport
4
network. The parties cooperating to define the specification are Ericsson AB, Huawei Technologies Co. Ltd,
5
NEC Corporation and Nokia.
6
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Motivation for eCPRI:
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Compared to CPRI [1], eCPRI makes it possible to decrease the data rate demands between eREC and
9
eRE via a flexible functional decomposition while limiting the complexity of the eRE.
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Scope of Specification:
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The necessary items for transport, connectivity and control are included in the specification. This includes
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User Plane data, Control and Management Plane transport mechanisms, and means for synchronization.
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The eCPRI specification supports 5G and enables increased efficiency in order to meet the needs foreseen
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for 5G Mobile Networks. In contrast to CPRI, the eCPRI specification supports more flexibility in the
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positioning of the functional split inside the Physical Layer of the cellular base station.
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The scope of the eCPRI specification is to enable efficient and flexible radio data transmission via a packet
18
based fronthaul transport network like IP or Ethernet. eCPRI defines a protocol layer which provides various
19
- mainly User Plane data specific - services to the upper layers of the protocol stack.
20
The specification has the following scope (see Figure 1, Figure 1A and Figure 1B):
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1. The internal radio base station interface establishing a connection between “eCPRI Radio Equipment
22
Control” (eREC) and “eCPRI Radio Equipment” (eRE) via a packet based transport network is
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specified.
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2. Three different information flows (eCPRI User Plane data, C&M Plane data, and Synchronization
25
Plane data) are transported over the interface.
26
3. The specification defines a new eCPRI Layer above the Transport Network Layer. Existing standards
27
are used for the transport network layer, C&M and Synchronization.
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eCPRI Radio Equipment Control (eREC)
eCPRI
specific
User Plane
Sync C&M
eCPRI Radio Equipment (eRE)
Transport Network Layer
Standard
Protocols
SAP
U
SAP
S
SAP
CM
eCPRI
specific
User Plane Sync C&M
Transport Network Layer
Standard
Protocols
SAP
U
SAP
S
SAP
CM
Transport Network
30
Figure 1: System and Interface Definition
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The eCPRI interface can also be used between two eRECs or between two eREs as well as with
32
Interworking Function(s) (IWF) located between the eCPRI transport network and one/several CPRI node(s).
33
In Figure 1A the Interworking Function is located between the eCPRI transport network and one/several
34
CPRI RE node(s). The SAPs shall be terminated at both eCPRI and CPRI ends and bridged to each other
35
via vendor specific functionality. For this configuration IWF type 0 is used.
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eCPRI Specification V2.0 (2019-05-10)
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In Figure 1B the Interworking Functions are located between the respective CPRI nodes and the transport
1
network. The Interworking Functions bridge the CPRI link over the Fronthaul Transport Network. For this
2
configuration IWF type 1 and type 2 are used.
3
4
CPRI Radio Equipment Control (eREC)
User
Plane
Sync C&M
eCPRI
specific
SAP
U
SAP
S
SAP
CM
User
Plane
Sync
C&M
CPRI Radio Equipment (RE)
Layer 2
SAP
IQ
SAP
S
SAP
CM
Standard
Protocols
Transport Network Layer
User Plane
Sync C&M
eCPRI/CPRI Interworking Function type 0
Layer 2
SAP
IQ
SAP
S
SAP
CM
eCPRI
specific
User Plane
Sync
C&M
Standard
Protocols
SAP
U
SAP
S
SAP
CM
IWF
Layer 1
Layer 1
Transport Network Layer
Transport
Network
5
6
Figure 1A: System and Interface Definition with eCPRI/CPRI IWF type 0
7
8
CPRI Radio Equipment Control (REC)
User Plane Sync C&M
Layer 1
Layer 2
SAP
IQ
SAP
S
SAP
CM
Transport Network
User Plane
Sync C&M
CPRI Radio Equipment (RE)
Layer 1
Layer 2
SAP
IQ
SAP
S
SAP
CM
IWF
type 2
IWF
type 1
9
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Figure 1B: System and Interface Definition with eCPRI/CPRI IWF type 1 and type 2
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