Optional Transmission Interfaces

2.2.1 ZWF22-03-051 IP over E1

Benefits

This feature supports IP over E1, conveniently fulfilling all-IP networking of UTRAN with existing low rate E1 link.

Description

The E1 physical interface complies with ITU-T G.703 standard. The allowed jitter of the physical interface complies with ITU-T G.823 standard. The structure of the frame which is transferred over the E1 interface complies with the ITU-T G.704 standard. The E1 has 32 timeslots numbered 0 to 31. Where, timeslot 0 is used to carry the synchronization information of the clock, and timeslot 16 for carrying the control signals (also transferring information signals if necessary). If out-of-band common channel signaling (CCS) is adopted, the timeslot 16 don^"t need to transfer signaling, it can also carry data. Other timeslots can carry data. ZTE uses the 31 timeslots to transfer data. An E1 supports the physical bandwidth of 1984 kbps.

Figure 2-4 PPP/MLPPP Protocol Stack

IP

E1 HDLC

PPP

HDLC PPP MLPPP/MCPPP

HDLC PPP

ZTE RAN equipment supports IP over E1 by PPP and ML/MC-PPP protocol, the protocol stacks are described in Figure 3-11. PPP protocol processing complies with RFC1661 and RFC1332 criterion, MLPPP processing complies with the RFC1990 criterion, and the MCPPP processing complies with the RFC 2686 criterion.

MLPPP can integrate multiple PPP low rate links into one high rate link. MCPPP supports up to 4 classes of priority (0~3, class 0 is the highest priority and class 3 is the

lowest one). MCPPP can guarantee the preferential processing for high priority service in narrowband link.

When there are many low rate links, no matter PPP or MLPPP, the protocol can be set at the OMC. In MLPPP mode, which links to group an MLPPP can be set at the OMC as well. If some links fail when many low rate links grouped with MLPPP, the transmission bandwidth of whole MLPPP group is influenced, but other links still guarantee that the MLPPP group can serve the upper layer.

Introduced Version

U9.1&Before

Enhancement

No

2.2.2 ZWF22-03-055 IP over Optical GE

Benefits

This feature supports IP over optical GE, providing higher transmission bandwidth and farther transmission distance by optical fiber.

Description

Optical GE transmission supported by ZTE RAN equipment complies with IEEE 802.3z standards. The transmission media include long-wave single-mode or multi-mode fiber (meets 1000Base-LX criterion), short-wave multi-mode fiber (meets 1000Base-SX criterion), the data rate can reach 1000Mbps.

ZTE RAN equipment supports GE mode, IEEE 802.3 standard Ethernet frame structure and VLAN frame structure which meets IEEE802.1Q and 802.1P criterions.

Introduced Version

U9.1&Before

Enhancement

No

2.2.3 ZWF22-03-056 IP over Optical FE

Benefits

This feature supports IP over optical FE in Node B, providing higher transmission bandwidth and farther transmission distance by optical fiber.

Description

Optical FE transmission supported by ZTE Node B complies with IEEE 802.3 standards.

The transmission media includes single-mode or multi-mode fiber (meets 100Base-FX criterion), the data rate can reach 100Mbps.

ZTE Node B equipment supports FE fiber mode, IEEE 802.3 standard Ethernet frame structure and VLAN frame structure which meets IEEE802.1Q and 802.1P criterions.

Introduce Version

U9.1&Before

Enhancement

No

2.2.4 ZWF22-03-010 IEEE 1588

Benefits

This feature supports synchronizing Node B from IP transmission network via IEEE 1588 V2 protocol. It solves the problem that the Node B cannot synchronize to BITS clock source or transmission line as well as avoiding the high investment on GPS.

Description

 As an asynchronous netw ork, the clock synchronization between RNC and Node B isn^"t needed in UMTS. But the frequency deviation may be out of scope after long time running because the high-precision clock can^"t be provided in the Node B, and the UE

handover between different Node Bs may be influenced. So the Node B should be synchronized to the high-precision clock to guarantee network KPI. The accuracy of frequency synchronized is 0.05ppm.

ZTE supports IEEE1588 network time synchronization protocol (also called Precision Time Protocol), which synchronizes clock to a distributed system consisting of one or more nodes by network communication. This protocol adopts the master-slave synchronization mode. The slave port can obtain synchronization information from the master port to implement high-precision clock synchronization.

IEEE 1588 clocks can be used for clock synchronization when FE or GE transmission is used on the Iub interface. The IEEE 1588 clock synchronization function is completed by RNC and Node B together. The RNC serves as Master that provides exact clock source.

The Node B serves as Slave that extracts the clock information and performs the clock synchronization. The clock precision may be influenced by the delay and the jitter of the network if the IP network between RNC and Node B is complex and the number of middle nodes is numerous. The clock source can also be set at a certain transmission node from which Node B can obtain the clock synchronization by IEEE 1588.

To fulfill clock precision defined by 3GPP specification, there are some requirements on the transmission link between the IEEE 1588 clock source and the Node B:

− One trip transport delay <= 20ms

− Transport delay variation <=7ms

− Frame loss rate <=0.05%

ZTE also supports clock synchronization from the switch via IEEE 1588 protocol. The switch serves as Master that provides high ^#precision clock; the Node B serves as Slave that extracts the clock information and performs the clock synchronization to avoid the delay and the jitter generated by the complex transport network. The typical network architecture is shown below.

Figure 2-5 Application of IEEE 1588 Clock Synchronization

Introduced Version

U11.2

Enhancement