05_ra41125en05gla0_flexi multiradio lte bts transport

8/10/2019 05_RA41125EN05GLA0_Flexi Multiradio LTE BTS Transport

1/32RA41125EN05GLA0

LTE Radio Access System - Transport

1


2/32RA41125EN05GLA0


2


3/32RA41125EN05GLA0


3


4/32RA41125EN05GLA0


4


5/32RA41125EN05GLA0


5


6/32RA41125EN05GLA0


6


7/32RA41125EN05GLA0


7


8/32RA41125EN05GLA0


8


9/32RA41125EN05GLA0


9


10/32RA41125EN05GLA0


10

Extra capacity for X2 is negligible compared to S1 (


11/32RA41125EN05GLA0


11


12/32RA41125EN05GLA0


12


13/32RA41125EN05GLA0


13


14/32RA41125EN05GLA0


14

Feature limitations

Transport Admission Control is limited by five major factors which are inherent to the approachand need to be clearly understood:

TAC has no information about the traffic situation for any other eNB, routers in the transportbackhaul network, nor about core network elements (SAE gateway, MME). It cannot work on aper-route basis, but only use the information it has available at the eNB where it is located.

TAC makes a decision to accept or reject a connection only at the moment it is requested. ForGBR traffic, information about the expected bit rate is available at this moment, but for non-GBR traffic, there is no knowledge and no control about the future user behavior. There is nopolicing functionality that enforces user behavior as announced at connection set-up time.

TAC expects that GBR traffic will be handled with higher priority than non-GBR traffic in thetransport scheduler and in the transport network. Non-GBR should be always suppressed there.However, mapping of traffic types to priorities (DSCP or PCP values) is configured by theoperator. Inappropriate assignments may lead to unexpected behavior.

TAC is applied to the user traffic only. Other traffic which is not necessarily visible on the airinterface, but provides additional load on the transport network, like for example: Timing overPacket data, must be considered in the dimensioning of TAC.


15/32RA41125EN05GLA0


15

NOTE 1:

A delay of 20 ms for the delay between a PCEF and a radio base station should be subtracted from a

given PDB to derive the packet delay budget that applies to the radio interface. This delay is the averagebetween the case where the PCEF is located "close" to the radio base station (roughly 10 ms) and thecase where the PCEF is located "far" from the radio base station, e.g. in case of roaming with homerouted traffic (the one-way packet delay between Europe and the US west coast is roughly 50 ms). Theaverage takes into account that roaming is a less typical scenario. It is expected that subtracting thisaverage delay of 20 ms from a given PDB will lead to desired end-to-end performance in most typicalcases. Also, note that the PDB defines an upper bound. Actual packet delays - in particular for GBR traffic- should typically be lower than the PDB specified for a QCI as long as the UE has sufficient radio channelquality.

NOTE 2:

The rate of non congestion related packet losses that may occur between a radio base station and aPCEF should be regarded as negligible. A PELR value is specified for a standardized QCI thereforeapplies completely to the radio interface between a UE and radio base station.

NOTE 3:This QCI is typically associated with an operator controlled service, i.e., a service where the SDFaggregate's uplink / downlink packet filters are known at the point in time when the SDF aggregate isauthorized. In case of E-UTRAN this is the point in time when a corresponding dedicated EPS bearer isestablished / modified.

NOTE 4:

This QCI could be used for prioritization of specific services according to operator configuration.

NOTE 5:

This QCI could be used for a dedicated "premium bearer" (e.g. associated with premium content) for anysubscriber / subscriber group. Also in this case, the SDF aggregate's uplink / downlink packet filters areknown at the point in time when the SDF aggregate is authorized. Alternatively, this QCI could be used forthe default bearer of a UE/PDN for "premium subscribers".

NOTE 6:

This QCI is typically used for the default bearer of a UE/PDN for non privileged subscribers. Note thatAMBR can be used as a "tool" to provide subscriber differentiation between subscriber groups connectedto the same PDN with the same QCI on the default bearer.


16/32RA41125EN05GLA0


16


17/32RA41125EN05GLA0


17


18/32RA41125EN05GLA0


18


19/32RA41125EN05GLA0


19


20/32RA41125EN05GLA0


20

Synchronization accuracy

In practice the number of chained eNBs depends on the input signal quality at the first eNB. Ifthe jitter/wander level is within the ITU-T limits in the whole chain, a maximum of 20 FlexiSystem Modules can be used. In SyncE networks, SyncE-filtered Ethernet Equipment Clock(EEC) is more reliable than ToP and fulfills Maximum Time Interval Error (MTIE) limit for E1(G.823) and T1 (G.824). Therefore SyncE networks use EEC to synchronize PDH and2.048MHz interfaces.

The ToP clock is additionally filtered by collocated system clock to fulfill G.823 requirements(packet delay variation, delay jumps) under all possible network conditions.

Synchronizing PDH and 2.048MHz outputs with eNB OCXO guarantees that potential

disturbances caused for example by ToP (like extensive wander) are filtered appropriately.However, output clock is no longer traceable to Primary Reference Clock (PRC) in such case.

Hold-over mode

If eNB loses all sync sources, it switches to hold-over mode. Then the eNB OXCO keepsrunning with the last known control value and the sync output becomes squelchable.

The 2.048MHz output signal can be squelched when the ext2M048ClkOutOn flag is set to false.

Note that the parameter controls can be switched ON/OFF in hold-over mode.


21/32RA41125EN05GLA0


21


22/32RA41125EN05GLA0


22


23/32RA41125EN05GLA0


23


24/32RA41125EN05GLA0


24


25/32RA41125EN05GLA0


25


26/32RA41125EN05GLA0


26

E-Line

The mobile backhaul network can be purely based on L2 (Ethernet) transport. Point-to-pointEthernet Virtual Connections (EVC) between a User Network Interface (UNI) at the eNBs andanother UNI at the (redundant) edge router are the straightforward solution. EVC attributes canbe well controlled (see [MEF10.1]) and commercial services are commercially available inmany markets, known as E-Line services (Ethernet leased lines). In this scenario each VLANwould identify a individual eNB.

E-Tree

Point-to-multipoint Ethernet Virtual Connections (EVC) between UNI at the edge router and UNIat the eNB. Similar to E-Line in that eNBs will not be able to communicate directly to eachother (traffic separation similar to point-to-point), but simpler to provision due to common pointat the edge router.

E-LAN

As an alternative, the Mobile Backhaul Network could be built based on multipoint-to-multipointEVCs (E-LAN service). Most appropriately, eNBs belonging to one group should be assigned toone E-LAN (Figure 18). At the UNI between Mobile Backhaul and Core Network, the VLAN IDidentifies an eNB group.


27/32RA41125EN05GLA0


27


28/32RA41125EN05GLA0


28

E-Line

The mobile backhaul network can be purely based on L2 (Ethernet) transport. Point-to-pointEthernet Virtual Connections (EVC) between a User Network Interface (UNI) at the eNBs andanother UNI at the (redundant) edge router are the straightforward solution. EVC attributes canbe well controlled (see [MEF10.1]) and commercial services are commercially available inmany markets, known as E-Line services (Ethernet leased lines). In this scenario each VLANwould identify a individual eNB.

E-Tree

Point-to-multipoint Ethernet Virtual Connections (EVC) between UNI at the edge router and UNIat the eNB. Similar to E-Line in that eNBs will not be able to communicate directly to eachother (traffic separation similar to point-to-point), but simpler to provision due to common pointat the edge router.

E-LAN

As an alternative, the Mobile Backhaul Network could be built based on multipoint-to-multipointEVCs (E-LAN service). Most appropriately, eNBs belonging to one group should be assigned toone E-LAN (Figure 18). At the UNI between Mobile Backhaul and Core Network, the VLAN IDidentifies an eNB group.


29/32RA41125EN05GLA0


29


30/32RA41125EN05GLA0


30


31/32RA41125EN05GLA0


31


32/32


Note:

FSMF includes:

One optical interface which can be used as OBSAI RP3-01 interface with up to 6 Gbit/s or as1000Base-X as network interface

One electrical interface 1000Base-T as network interface

05_ra41125en05gla0_flexi multiradio lte bts transport

Documents