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8.3.3.5 subframeId (subframe identifier)
See clause (7.4.4.5) subframeId in U-plane message shall be set to the subframeId value signaled in the corresponding C-plane message.
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8.3.3.6 slotId (slot identifier)
See clause (7.4.4.6) slotId in U-plane message shall be set to the slotId value signaled in the corresponding C-plane message.
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8.3.3.7 symbolId (symbol identifier)
Description: This parameter identifies a symbol number within a slot. When a C-plane message describes a single symbol (or in case of PRACH, a single PRACH repetition), symbolId in the U-plane message for that symbol (or PRACH repetition) shall be set to the startSymbolId value signaled in the C-plane message. When a C...
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8.3.3.8 sectionId (section identifier)
See clause (7.4.5.1)
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8.3.3.9 rb (resource block indicator)
See clause (7.4.5.2)
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8.3.3.10 symInc (symbol number increment command)
See clause (7.4.5.3)
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8.3.3.11 startPrbu (startingPRB of user plane section)
Description: This parameter is the starting PRB (lowest frequency) of a user plane data section. Values of rb, startPrbu and numPrbu shall ensure that data sections shall never overlap: a single PRB (a block of 12 resource elements consecutive in frequency) may only exist within one data section for a given eAxC. For o...
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8.3.3.12 numPrbu (number of PRBs per user plane section)
Description: This parameter defines the number of PRBs (blocks of 12 resource elements consecutive in frequency) in the user plane data section. If the parameter rb (see 6.3.3.9) is zero, then the PRBs in the user plane data section shall be consecutive in the frequency. Otherwise the set of PRBs includes only every ot...
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8.3.3.13 udCompHdr (user data compression header)
Description: This parameter defines the compression method and IQ bit width for the user data in a data section. This means that, in the DL at least, each data section can in principle have a different udCompHdr value. In the UL, the O- RU shall copy the received udCompHdr value in the C-plane message to the udCompHdr ...
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8.3.3.14 reserved (reserved for future use)
Description: This parameter provides 1 byte for future definition, should be set to all zeros by the sender and ignored by the receiver. This field is only present when udCompHdr is present, and is absent when the static IQ format and compression method is configured via the M-Plane. Value range: {0000 0000b-1111 1111b...
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8.3.3.15 udCompParam (user data compression parameter)
Description: This parameter applies to whatever compression method is used for the PRB (configured statically via M- Plane or specified in udCompHdr of the data section containing the PRB). Value range: {0000 0000b-1111 1111b}. Bit allocations udCompMeth 0 (msb) 1 2 3 4 5 6 7 (lsb) compParam size 0000b = no compression...
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8.3.3.16 iSample (in-phase sample)
Description: This parameter is the In-phase sample value. When the optional “little endian byte order” is chosen via M- plane, refer to Annex D.2 for detail byte order, otherwise see Annex D.1 for example sample formatting. Value range: {all zeros – all ones}. Type: signed integer. Field length: 1-16 bits.
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8.3.3.17 qSample (quadrature sample)
Description: This parameter is the Quadrature sample value. When the optional “little endian byte order” is chosen via M-plane, refer to Annex D.2 for detail byte order, otherwise see Annex D.1 for example sample formatting. Value range: {all zeros – all ones}. Type: signed integer. Field length: 1-16 bits.
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8.3.3.18 sReSMask (Selective RE Sending Mask)
Description: This parameter defines the IQ usage mask when using the compression methods block floating point + Selective RE sending or modulation compression + Selective RE sending. IQ-samples in corresponding PRB that are included in the U-plane message are indicated with bit-value 1b in the mask. IQ-samples that are...
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8.3.3.19 udCompLen (PRB field length)
Description: This parameter specifies the total number of octets including padding in the PRB fields up to the end of current section. The maximum supported PRB field length is 216-1, but the actual size may be further limited by the maximum payload size of the underlying transport network. This field is only present f...
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8.3.4 DL Data Precoding
• Section Extension ‘3’ is used for C-plane and associated sectionID for U-plane • O-RU shall understand that for this Section Extension, O-RU should read 12 REs which have CRS reference signals in that PRB. • O-RU shall understand the crsShift and crsReMask field to map appropriately the CRS REs to each antenna port T...
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8.3.5 Data Transfer for Special Cases
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8.3.5.1 Data Message Mapping and Packetization
See clause 8.3.2.
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8.3.5.2 Uplink Data Transfer
Uplink IQ data transfer is covered in clause 8.3.2. In particular, PRACH and other common channels as well as SRS and other reference signal channels use the same frequency domain IQ data packetization as with user data channels (PDSCH, PUSCH) following the transfer procedure described in clause 8.2.1. Alternatively, P...
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8.3.5.3 PRACH Data Transfer Without C-Plane
In addition to general uplink data transfer (see 6.3.5.2), PRACH related IQ data may be transferred using the IQ data transfer procedure without C-plane (see clause 8.2.2). In this case parameters controlling signal reception and sending ETSI ETSI TS 103 859 V7.0.2 (2022-09) 175 U-plane messages are provided via M-plan...
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8.3.5.4 SRS Data Transfer Without C-Plane
In addition to the general uplink data transfer (see 6.3.5.2), SRS related IQ data may be transferred with IQ data transfer procedure without C-plane (see clause 8.2.2). In this case parameters controlling signal reception and sending U-plane messages are provided via M-plane. Refer to “Static SRS” in M-Plane specifica...
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8.4 U-Plane Optimizations
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8.4.1 Coupling via Frequency and Time
Coupling between C-Plane section descriptions and U-Plane data sections via frequency and time (for more details see clause 7.4.1.2.2) is mode of operation enabled by eAxC via M-plane. It allows to optimize U-Plane message size by combining data sections that are continuous in frequency and are within the same symbol. ...
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9 Counters and KPIs
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9.1 Counters
This clause defines recommended ORAN CU-Plane specific performance counters for the fronthaul interface. Table 9-1 defines the set of mandatory and optional ORAN performance counters to be implemented within an O-RU or O- DU. These counters are defined from the perspective of the O-RU’s or O-DU’s Ethernet interfaces. T...
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10 Specification Mandatory and Optional Capabilities
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10.1 General
This clause provides details regarding which capabilities within the specification are mandatory and which are optional. The list will in general be different for the O-DU versus the O-RU because in many cases, the O-DU will need to implement multiple options as mandatory to ensure interoperability with O-RUs that have...
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11 S-Plane Protocol
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11.1 General
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11.1.1 Overview
Time and frequency synchronization can be distributed to the O-DU and O-RU in different manner. However, synchronization accuracy is mostly impacted by implementation (e.g., timestamping near the interfaces, number of hops) than by the technology itself. The following synchronization options are available over an Ether...
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11.2 Synchronization Baseline
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11.2.1 List of Reference Documents
See clause 2.
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11.2.2 Clock Model and Synchronization Topology
Different O-RAN synchronization topologies are necessary to address different deployment market need. The following 4 topology configurations are considered by O-RAN as compliant topologies for supporting the O-RU synchronization needs. A configuration label is used for easier reference through this specification: • Co...
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11.2.2.1 Topology configuration LLS-C1 and LLS-C2 Synchronization
Configuration LLS-C1 is based on point-to-point connection between O-DU and O-RU using network timing option. As shown in Figure 11-1 below, it is basically the simplest topology for network timing option, where O-DU directly synchronizes O-RU. Configuration LLS-C2 is similar to LLS-C1 with O-DU acting as master to dis...
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11.2.2.2 Topology configuration LLS-C3 Synchronization
Configuration LLS-C3 is similar to LLS-C2 except frequency and time distribution is made by the fronthaul network itself (not by the O-DU). That means that one or more PRTC/T-GM are implemented in the fronthaul network to distribute network timing toward O-DU and O-RU. One or more Ethernet switches are allowed between ...
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11.2.2.3 Topology configuration LLS-C4 Synchronization
O-RAN maintains network timing distribution as the preferred approach within the fronthaul network, however, there could be some deployment use cases that prevent the fronthaul network (or only a section of the network) from being upgraded to G.8271.1 compliance and meeting the target performance at the O-RU. To cover ...
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11.2.3 Clock Synchronization
The following requirements are provided for clock synchronization: • For Full Timing Support networks (either upstream O-DU or fronthaul between O-DU and O-RU), PLFS (typically SyncE) shall be used within the fronthaul network distribution per ITU-T G.8271.1, G.8275.1 and G.8273.2. In an LLS-C1 configuration, the O-DU ...
bedca00b77bd2bcaa5a1804601b66e93
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11.2.4 Profiles
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11.2.4.1 Physical Layer Frequency Signals (PLFS)
An implementation providing SyncE shall: • Support ITU-T G.781 Option 1 Quality Level (per clause 5.4 Quality Code of ITU-T G.781) o Support ITU-T G.781 other options, is for further study. ITU-T G.8271.1 analysis has only been done with a synchronous Ethernet network based on option 1 EECs or eEECs. • Support ITU-T G....
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11.2.4.2 PTP
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11.2.4.2.1 Full Timing Support
Use of IEEE 1588 or PTP for time/phase synchronization shall be according to its clauses referred by ITU-T G.8275.1 (Full Timing Support). Notes: • The T-TSC inside the O-RU and O-DU are considered as T-TSC inside 3GPP end application modules. Such T-TSC may not provide a 1PPS measurement interface, and ITU-T G.8273.2 ...
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11.2.4.2.2 Partial Timing Support
Support of Partial Timing Support using ITU-T G.8275.2 Telecom Profile is currently considered as permissible but requires additional considerations: • Partial Timing Support allows switches with no T-BC or T-TC, hence there is no guarantee of synchronization performance based on ITU-T standard specification such as G....
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11.2.5 Synchronization Accuracy
The parameters Time Error and other derived metrics are used in the subsequent clauses of this document. The definition of Time Error function, TE(t) is given in clause 3.1. For a synchronized clock or timing signal, the Time Error function is composed of several different error components which contribute to the total...
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11.2.5.1 Jitter
Within the O-RAN fronthaul network, all network equipment (NE) supporting SyncE transport across the network shall comply with input and output jitter requirements specified in ITU-T G.8262 (for EEC) or ITU-T G.8262.1 (for eEEC). Alternate PLFS implementations are for further study.
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11.2.5.2 Wander
Within the O-RAN fronthaul network, all network equipment (NE) supporting SyncE transport across the network shall comply with input and output wander requirements specified in ITU-T G.8262 (for EEC) or ITU-T G.8262.1 (for eEEC). Alternate PLFS implementations are for further study.
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11.2.5.3 Air interface frequency error
The O-RAN fronthaul network shall ensure O-RU meeting a +/-50ppb air interface frequency error requirement. 3GPP TS 36.104 (for LTE macro cells) and TS 38.104 (for 5G macro ceO) specify +/-50ppb as the short-term average error in 1ms duration applicable to both LTE and 5G technologies. Refer to clause 11.3.2 for more d...
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11.2.5.4 Air interface maximum time error
The O-RAN fronthaul network shall ensure O-RU meeting the following air interface time alignment error (|TAE| absolute or relative) requirements based on different features in LTE and 5G technologies. For features covered by 3GPP, they are specified in TS 36.104 (for LTE) and TS38.104 (for 5G). The following figure sho...
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11.3 Time and Frequency Synchronization Requirements
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11.3.1 Allowed PTP and PLFS clock types and clock classes
A network element (NE) may use the following clock types and classes to support PTP and PLFS, and can be used among other such NEs to build an O-RAN-compliant fronthaul network meeting end-to-end frequency synchronization requirements as well as time synchronization requirements at the air interface. • EEC (per ITU-T G...
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11.3.2.3 Configuration LLS-C4
The following table summarizes the frequency and time error budgets across different elements. • O-DU output measurement signal (1PPS): there is no such allocated frequency error budget as for LLS-C1/C2. Only time error shall be within ±1500ns limits as specified in clause 4.3. In case the O-DU is synchronized using a ...
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11.4 Node Behavior Guidelines
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11.4.1 Configurations LLS-C1 and LLS-C2
This clause covers O-RAN topology configurations LLS-C1 and LLS-C2 where the O-DU acts as PLFS and PTP master. The operation of O-DU and O-RU during holdover and other related states is described in Table 11-6. O-RU holdover and O-DU holdover are independent events. Likewise, O-RU holdover behavior is optional (not man...
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11.4.1.1 M-Plane disconnected
O-RAN allows hybrid M-plane model with M-plane communication between • O-RU and O-DU • O-RU and Service Management and Orchestration (SMO) function As a result, the following M-plane disconnected events shall be considered: • O-DU detects loss communication to O-RU • SMO detects loss communication to O-RU • O-RU detect...
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11.4.1.2 O-RU in the FREERUN State
O-DU If synchronization state on a connected O-RU transits to the FREERUN state, the O-DU shall stop sending C-Plane and U-Plane related data to the O-RU unless otherwise specified. When O-RU transits to LOCKED state, O-DU shall request carriers to be switched to ACTIVE to reenable transmission. Rationale: The O-DU rec...
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11.4.1.3 O-DU in the FREERUN state
O-DU If an O-DU transits to the FREERUN state, the O-DU shall disable RF transmission on all connected O-RUs, and keep it turned off until synchronization is reacquired. NOTE: The O-DU shall support configuration option that allows O-DU to operate outside of the required synchronization limits, or without any synchroni...
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11.4.1.4 Operation in LOCKED/HOLDOVER state
Whether in “LOCKED” or “Holdover” state, it is expected that O-DU monitors the “LOCKED/HOLDOVER” status of the O-RUs under its management. O-DU ETSI ETSI TS 103 859 V7.0.2 (2022-09) 206 • In configuration LLS-C1 and LLS-C2: by collecting the O-RUs’ “LOCKED” or “HOLDOVER” state, as well as the received PLFS and PTP qual...
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11.4.2 Configurations LLS-C3
This clause covers O-RAN topology configuration LLS-C3 based on IEEE 802.1CM bridging network. PRTC/GM is provided by the fronthaul network. The operation of the Fronthaul network elements, O-DU and O-RU during holdover and other related states is described in Table 11-7. O-RU holdover and O-DU holdover are independent...
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11.4.2.1 M-Plane disconnected
This clause is same as 11.4.1.1
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11.4.2.2 O-RU in the FREERUN State
This clause is same as 11.4.1.2
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11.4.2.3 O-DU in the FREERUN state
NOTES: - if O-DU and O-RU are synchronized from the same fronthaul network and are connected to neighbor nodes in this network, it is most probable that the event leading to O-RU transiting to the FREERUN state will also lead to the same transition at the O-DU. - if O-DU has backup frequency and time source, such as lo...
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11.4.2.4 Operation in SYNCED/HOLDOVER state
Whether in “LOCKED” or “HOLDOVER” state, it is expected that O-DU monitors the “LOCKED” or “HOLDOVER” state, as well as the received PLFS and PTP quality status. This is same as configurations LLS-C1 and LLS-C2 described in earlier clause.
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11.4.3 Configurations LLS-C4
This clause covers O-RAN topology configurations LLS-C4 where the O-RU is synchronized by local PRTC (typically a GNSS receiver). The operation of O-DU and O-RU during holdover and other related states is described in Table 11-8. O-RU holdover and O-DU holdover are independent events. Likewise, O-RU holdover behavior i...
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11.4.3.1 M-Plane disconnected
This clause is same as 11.4.1.1
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11.4.3.2 O-RU in the FREERUN State
This clause is same as 11.4.1.2
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11.4.3.3 O-DU in the FREERUN state
O-DU If an O-DU transits to the FREERUN state, the O-DU shall disable RF transmission on all connected O-RUs and keep it turned off until synchronization is reacquired again. NOTE: The O-DU may support a configuration option that allows O-DU to operate outside of the required synchronization limits, or without any sync...
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11.4.3.4 Operation in SYNCED/HOLDOVER state
Whether in “LOCKED” or “HOLDOVER” state, it is expected that O-DU monitors the “LOCKED” or “HOLDOVER” state. This is same as configurations LLS-C1 and LLS-C2 described in earlier clause.
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11.5 S-Plane Handling in Multiple Link Scenarios
Behavior of S-Plane in scenarios with multiple links shall be based on the following principles: O-DU - Grand Master (configurations LLS-C1 & LLS-C2) There shall be an input sync reference signal on at least one link to an O-RU. Likewise, it is not prohibited to have input reference signal on multiple or all links to a...
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11.6 Announce Messages
O-RU shall check the following advertised parameters against a list of acceptable values based on its own design (assumed to be M-Plane configurable): • Domain Number: Default: 24 (for Full Timing Support per ITU-T G.8275.1) or 44 (for Partial Timing Support per ITU-T G.8275.2) • PTP Acceptable Clock Classes: o Default...
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11.7 Elementary Procedures
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11.7.1 PTP Time Synchronization procedure
All procedures used to exchange time related information between a time synchronization master and subordinate shall be compliant to the ITU-T G.8275.1 or G.8275.2 telecom profile, which provides necessary details on utilization of the IEEE 1588 protocol in telecom applications.
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11.7.2 System Frame Number Calculation from GPS Time
The general framework for System Frame Number (SFN) calculation from GPS (or GNSS) time is based on the following premises: • PTP time on the fronthaul interface shall use PTP timescale • The PTP epoch is 1 January 1970 00:00:00 TAI, which is 31 December 1969 23:59:51.999918 UTC. • PTP time on the fronthaul interface s...
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12 Beamforming Functionality
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12.1 General
The following clauses describe terminologies, rules, properties and uses cases related to beamforming and its functionalities. It is the baseline to follow by the O-DU, O-RU and modeling in M-plane.
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12.2 Hierarchy of Radiation Structure in O-RU
The hierarchy of radiation structure in O-RU is depicted in Figure 12-1 and described below: Figure 12-1. Hierarchy of Radiation Structure • O-RU: each O-RU can have 1 or several Panels • Panel: each panel can have 1 or several TX-antenna-arrays/RX-antenna-arrays • TX-antenna-array/RX-antenna-array: o TX-antenna-array/...
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12.3 Calibration
Calibration is the functionality of eliminating/minimizing relative amplitude and phase differences over frequency domain or time delay over the time domain between the array elements belonging to same TX-antenna-array/RX- antenna-array (including effect of front-end analog filters). Calibration can also be applied bet...
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12.4 beamId Use for Various Beamforming Methods
There are two main domains in which beamforming is executed, frequency-domain and time-domain; it is also possible to combine both (called “hybrid beamforming”). Frequency-domain beamforming is done between the RE mapping and FFT/iFFT processing stages (in UL and DL respectively) so is inherently a digital operation. T...
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12.4.1 Predefined-beam Beamforming
When implementing index-based beamforming, it is necessary for the O-RU to convey to the O-DU whether the beamforming type is frequency-domain, time-domain, or a mixture of the two (“hybrid beamforming”). In the case of frequency-domain-only or time-domain-only, the beamId is simply an index to the desired beamforming ...
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12.4.1.1 Beam Characteristics
In order to use predefined-beam beamforming in a standardized way, O-RAN considers beamforming to be defined such that energy (in the DL) or sensitivity (in the UL) is focused into either a “coarse” or “fine” granularity with possible overlaps. In this way “broadcast” beams may be used to cover a wider area with less p...
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12.4.2 Weight-based dynamic beamforming
Real-time-updated-weight-based beamforming operates the same as index-based beamforming, except that the need for the O-DU to convey actual beam weights to the O-RU introduces additional complexity. 12.4.2.1 Weight-based dynamic frequency-domain or time-domain beamforming (not hybrid) In the case of either frequency-do...
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12.4.2.2 Weight-based dynamic hybrid beamforming
Here two sub-cases are considered, wherein for one sub-case both the frequency-domain and time-domain weights may be updated in real-time, and for the second sub-case the frequency-domain weights may be updated in real-time but the time-domain beams are fixed.
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12.4.2.2.1 Hybrid beamforming with updatable frequency-domain and time-domain weights
For this sub-case the beamforming weight vector is a composite of the frequency-domain weights and the time-domain weights so can be considered as simply a longer weight vector. Where a block-based beam weight compression is employed (block floating point, block scaling or μ-law compression), the block size is a single...
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12.4.3 Attribute-based dynamic beamforming
Attribute-based dynamic beamforming operates similarly to weight-based dynamic beamforming except that it is inherently a time-domain beamforming operation (both are “dynamic” meaning the definition of a beam as indicated by a beamID value may be changed via a C-Plane message). Also, instead of beamforming weights asso...
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12.4.4 Channel-information-based beamforming
As stated earlier, beamId is irrelevant and unused in the case of channel-information-based beamforming.
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12.5 O-RU Antenna Model supported by O-RAN
Knowledge of O-RU antenna model is critical for certain types of beamforming. The following model is applicable for O-RU with one or more antennas, where each antenna has array of elements that are • uniform (all elements have same properties) and • organized into rectangular array (with rows and columns) that is plana...
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12.5.1 Coordinate Systems
Some of parameters describing model of antenna related to coordinate system that defines three axes and three angles. There are two coordinate systems defined: • array coordinate system • O-RU coordinate system ETSI ETSI TS 103 859 V7.0.2 (2022-09) 222 The array coordinate system is presented below: Figure 12-6 : Array...
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12.5.2 O-RU Antenna Model Parameters
The O-RU antenna model can be described with following parameters: • K – number of array elements in array (note that K = M*N*P*Q) • M – number of rows of array elements in array. M>0; value 0 is reserved for future use. • N – number of columns of array elements in array. N>0; value 0 is reserved for future use. • P – ...
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12.5.3 Identification and Ordering of Array Elements
describes how numbers are assigned to array elements. The model assumes the number of array elements corresponding to frequency domain beamforming weight φk’ is the same for every k’ (0<k’<K’) and the elements corresponding to beamforming weights form a rectangular shape without overlapping i.e. every array element is ...
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12.5.4 Relations Between Array Elements
Beamforming methods that use dynamic beamforming with beamforming weights conveyed in C-plane messages (in contrast to predefined beams) require the O-DU to know that specific elements of one array is co-located with elements of another array e.g. RX array and TX array that use same set of radiators. In addition, one o...
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12.5.5 Model Usage
The O-RU antenna model reported by the O-RU consists of RX arrays and TX arrays. RX arrays and TX arrays represent a capability for transmitting/receiving RF signal related to an eAxC and - if beamforming is supported by O- RU on given array - beamforming capability. In this clause examples are presented: red and green...
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13 Support of Shared Cell
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13.1 General
This clause specifies support for “Shared Cell”. “Shared cell” is defined as the operation for the same cell (the cell can have one or multiple component carrier(s)) by several O-RUs. There are 2 cases for realizing shared cell shown in Figure 13-1. • FHM mode: Shared cell is realized by FHM and several O-RUs. In this ...
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13.2 Copy and Combine function
DL Copy function (shown in Figure 13-2): In downlink case, FHM retrieves eCPRI messages coming from O-DU as payload of Ethernet frames, copies them (the entire eCPRI message including eCPRI header and eCPRI payload) without any modifications as payload into Ethernet frames and sends them towards the O-RUs realizing the...
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13.2.1 Selective transmission and reception using beamId
In order to avoid unnecessary interference and noise enhancement, selective transmission and reception function can be useful and it can be realized with minimum implementation impact on both O-DU/O-RU by using beamId. The followings are noted for the selective transmission and reception function using beamId: • Predef...
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13.3 Delay management for Shared cell
Total fronthaul distance between O-DU and O-RU shall be reduced compared to the case when there are no FHM/Cascade O-RU. This is required in order to keep the same total fronthaul delay between O-DU and O-RU even in the presence of processing time at FHM/Cascade O-RU, and to ensure UL messages arrive at O-DU within O-D...
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13.3.1 DL delay management for Shared cell
Figure 13-6 : Delay model parameters for FHM mode (2 O-RUs case, i.e. Nm = 2, is illustrated as an example) Figure 13-7 : Delay model parameters for Cascade mode (3 O-RUs case, i.e. N=3, is shown as an example) It is assumed that additional delay due to combining in UL case is larger than copying in DL case. Therefore ...
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13.3.2 UL delay management for Shared cell
Figure 13-8 : Delay model parameters for FHM mode (2 O-RUs case, i.e. Nm =2, is illustrated as an example) UL delay model parameters for FHM mode are shown in Figure 13-8. Since FHM processing delay for combining UL U-Plane messages effectively adds to the total fronthaul delay between O-DU and O-RU, total fronthaul di...
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13.4 S-plane for Shared cell
The same synchronization framework and requirements specified in clause 11 also apply to the FHM, O-DU and O-RU for Shared cell, where the FHM (in the FHM mode), and the cascaded O-RU(s) (in the Cascade mode), are typically regarded as Ethernet switches on the synchronization chain, meeting the requirements specified f...
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13.4.1 Node behavior at O-RU in FREERUN state
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13.4.1.1 O-DU
If synchronization states on all O-RUs in a shared cell used for operating the same cell transit to the FREERUN or HOLDOVER state, the O-DU shall stop sending C-Plane and U-Plane related data to these O-RUs. In other words, the O-DU shall continue sending unless all O-RUs in the shared cell used for operating the same ...
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13.4.1.2 O-RU
If synchronization state on a cascade O-RU transits to the FREERUN state, the cascade O-RU shall autonomously stop RF transmission, switch all carriers to INACTIVE state and send a notification to the O-DU about synchronization and carriers state change. The Cascade O-RU shall enable to continue the function for copy a...