Page | 1 RoE demonstration May 2017

Radio over Ethernet demonstration Aleksandra Checko, PhD, Gert Schiellerup, PhD1

Abstract 5G mobile fronthaul is envisioned to be packet-based, utilizing main stream transport technologies

like Ethernet. Radio over Ethernet (RoE) is a Standard for Radio over Ethernet Encapsulations and

Mappings developed under IEEE 1914.3 working group. It enables transport of native IQ data over

Ethernet (Native RoE packet mapper), as well as supports structure-aware mappers and structure-

agnostic mapper for CPRI/OBSAI and other data formats. In this way legacy, e.g. Long Term Evolution (LTE)

equipment can be flexibly included in Ethernet-based fronthaul.

In this whitepaper we present a demonstration of RoE using a native time domain mapper. It can

be flexibly used in 5G and 4G deployments, for Cloud (or Centralized) Radio Access Network (C-RAN)

architecture, as well as for base stations architecture with Remote Radio Head (RRH) and non-centralized

Baseband Unit (BBU).

Introduction 5G mobile fronthaul is envisioned to be packet-based, utilizing main stream transport technologies

like Ethernet [1].

Traditionally, in a distributed base station architecture, functionalities were divided between

Remote Radio Head (RRH) (RF part) and Baseband Unit (BBU) (baseband part). This functional split can be

used in Cloud (or Centralized) Radio Access Network (C-RAN), where BBUs are centralized and virtualized

(Cloud-RAN). In order to reach a tradeoff between benefits of centralization and fronthaul requirements

on throughput and latency, several other functional splits are considered is various standardization

bodies, including 3GPP [2], as shown in Figure 2, and Small Cells Forum [3]. 3GPP adopts a nomenclature

of a Centralized and Distributed Unit (CU/DU) discussing functional splits. Traditional functional split used

for distributed base station architecture is called split 8 and splits with lower indices leave more

functionality on the cell site, in a DU.

1 Email: sales@mti-mobile.com, http://www.mti-mobile.com/

Page | 2 RoE demonstration May 2017

Mobile core networkInternet

Standalone base station

Centralized Unit

DU

RFDU

Radio Access Network

1)

2.1)

2.2)

RF

Figure 1 Mobile network adopting three RAN architectures: 1) standalone base station, with RRH collocated with BBU, 2)

C-RAN with base stations functions spitted into: 2.1) CU and DU or 2.2) CU, DU and RF

PDCPLow-RLC

High-MAC

Low-MAC

Resource mapping, precoding

iFFT, CP

PDCPLow-RLC

High-MAC

Low-MAC

Resource de-mapping

FFT, CP

Option 5Option 4 Option 6 Option 7-1Option 2Option 1

RRC

RRC

RF

RF

Option 8

Data

Data

High-RLC

High-RLC

Option 3

High-PHY

High-PHY

Option 7-2

Encoding

Option 7-3

Figure 2 Functional splits discussed in 3GPP. Figure based on one from [2]

Radio over Ethernet (RoE) is a Standard for Radio over Ethernet Encapsulations and Mappings

developed under IEEE 1914.3 working group, previously IEEE 1904.3. RoE enables transport of IQ data

over Ethernet (Native RoE packet mapper), as well as supports structure-aware mappers and structure-

agnostic mapper for CPRI/OBSAI and other data formats. As an example, the following architectures can

be supported, presented in Figure 3:

a) 5G Cloud Radio Access Network (C-RAN) using e.g. native RoE mapper. Currently IEEE

1914.3 addresses splits 8 and 7.1

b) 4G C-RAN or distributed base station architecture, with legacy RRHs with CPRI interface and

BBU running native Ethernet or CPRI

c) 4G/5G deployments with CPRI or another protocol enabled on RRH and BBU side.

MTI presents a RoE solution, here transmitting RoE Native time domain data. Usage of other types

of mappers, like RoE native frequency domain data sub type, RoE structure-agnostic data sub type and

RoE structure-aware data sub type are alternatives.

Page | 3 RoE demonstration May 2017

CU

DURoE

RoE

DURoE

CU

DURoECPRI or other

DURoECPRI or other

CU

DURoE CPRI

DURoE CPRI

RoECPRI

RoE

or

a) application of native RoE for 5G C-RAN b) application of structure-aware RoE for 4G C-RAN utilizing legacy RRHs

c) application of structure-agnostic RoE for 4G/5G C-RAN utilizing CPRI or other protocols

RoECPRI or other

Figure 3 Possible applications of various RoE mappers for 4G/5G deployments

RoE-enabled Remote Radio Head Traditional Remote Radio Head (RRH) contains: protocol implementations, like CPRI/OBSAI on the

interface with baseband unit (BBU) and signal processing blocks preparing the signal to be transmitted in

right bandwidth, on right frequency and desired quality. Looking towards 5G deployment we prepared a

RRH with RoE module. Synchronization solution needed to be added, as clocking information is no longer

provided via synchronous protocols, like CPRI. For the purpose of this demo GPS was used. In commercial

deployments, network-based solutions, like IEEE 1588v2, are alternative options.

Figure 4 4G RRH used in mass deployments

CFR/

DPD

DAC

ADC

Frequency filter

SRC

DUC

SRC

DDC

CPR

I/O

BSA

I

4G Remote Radio Head

Page | 4 RoE demonstration May 2017

Figure 5 RoE compliant RRH towards 5G

RoE demostration and performance evaluation

Figure 6 presents the lab setup. It is build around RoE compliant RRH (bottom right corner). RRH is

connected via a commericially available Ethernet switch to an in-house developed Base Station Emulator

acting as a baseband unit (BBU). The signal is demodulated via a vector signal analyzer and for the purpose

of uplink demo, a vector signal generator is used. Management of the RoE is done via a Command Line

Interface (CLI) presented on the PC (upper left corner).

Figure 7 presents a laboratory setup used for downlink demonstration. The IQ signal generated by

the BBU is encapsulated into RoE packets, passes through a commercially available Ethernet switch to

reach the RoE-enabled RRH. The signal is demodulated and an analysis is presented in Figure 8. Measured

Error Vector Magnitude (EVM) is 3.3%, which is below 3GPP requirements for 16QAM signals (36.104

requirement is 12.5% [4]). Frequency error is 7.5Hz which for the carrier frequency of 2.14GHz equals to

3.5 ppb (parts per billion). 3GPP 36.104 requirement is ±50ppb [4].

Figure 6 Lab setup

CFR/

DPD

DAC

ADC

SRC

DUC

SRC

DDC

RoE

5G prototype Remote Radio Head

Sync

Frequency filter

Page | 5 RoE demonstration May 2017

BB

RFRoE

Ethernet switch

RoE

Signal analyzerRemote Radio

HeadBaseband Unit

Downlink

GPS GPS

Xilinx ZC706

Figure 7 Downlink demo setup

Figure 8 DL demo signal analysis

Figure 9 presents the laboratory setup used for uplink demonstration. The IQ signal is generated by

a signal generator connected to an RRH. The Signal is encapsulated within RoE and passed through a

switch to reach the BBU. In order to analyze the signal, it is looped back, send from BBU encapsulated into

RoE packets, passed through Ethernet switch to reach the RoE-enabled RRH. Signal is here demodulated

in the attached signal analyzer and an analysis is presented in Figure 10. Measured EVM is 3.23%, which

is below 3GPP requirements for 64QAM signals (36.104 requirement is 8% [4]). Frequency error is 1.02Hz

Page | 6 RoE demonstration May 2017

which for the carrier frequency of 2.14GHz equals to 0.5 ppb (parts per billion). Again, 3GPP 36.104

requirement is ±50ppb [4].

BB

RFRoE

Ethernet switch

RoE

Signal analyzerRemote Radio

HeadBaseband Unit

Signal generator

Uplink

Loopedback uplink

GPS GPS

Xilinx ZC706

Figure 9 Uplink demo setup

Figure 10 UL demo signal analysis

Page | 7 RoE demonstration May 2017

Ethernet frames captured using Wireshark are presented in Figure 11.

Figure 11 Wireshark capture

Addressing delay and jitter performance Variable delay (jitter) is expected in packet-based networks. MTI’s RoE includes 312.5us buffer that

assures that data can be transmitted over air interface at configured presentation time with full data

integrity. Therefore delay becomes a choice, it is configurable. In case shorter/longer delay is experienced

over the link, buffer fill level will reach different values, as presented in Figure 12 and Figure 13.

Figure 12 Buffer allows variable fronthaul delay

BB

RFRoERoE

Remote Radio Head

Baseband Unit

GPS GPS

t

312.5us

BB

RFRoERoE

GPS GPS

t

312.5us

Buffer fill level

Buffer fill level

Page | 8 RoE demonstration May 2017

BB

RFRoERoE

Remote Radio Head

Baseband Unit

GPS GPS

t

312.5us

Buffer fill level

Figure 13 Buffer fill level when fronthaul network delay is variable

Conclusion MTI’s RoE IP core enables Ethernet-based fronthaul for 4G and beyond mobile networks.

Demonstrated transmission meets 3GPP EVM and frequency error requirements and allows for variable

delays on fronthaul network. Here, a prototype of RoE Native time domain data mapping was presented.

Usage of other types of RoE subtypes, like RoE native frequency domain data sub type, RoE structure-

agnostic data sub type and RoE structure-aware data sub type, are alternatives.

References

[1] China Mobile Research Institute, Alcatel-Lucent, Nokia Networks, ZTE Corporation,

Broadcom Corporation, Intel China Research Center, "White parer of Next Generation

Fronthaul Interface v1.0," 2015. [Online]. Available: http://labs.chinamobile.com/cran/.

[2] 3GPP, "Study on new radio access technology: Radio access architecture and interfaces

( TR 38.801 v14.0.0, Release 14)," March, 2017.

[3] Small Cell Forum, "Small Cell Virtualization Functional Splits and use cases, 159.05.1.01,"

June 2015.

[4] 3GPP, "Evolved Universal Terrestrial Radio Access (E-UTRA); Base Station (BS) radio

transmission and reception ( TS 36.104 v12.6.0, Release 12)," December, 2014.

Page | 9 RoE demonstration May 2017

About MTI Mobile Microelectronics Technology Inc. (MTI)—headquartered in Taiwan—is a leading global provider of

products and solutions for the wireless telecommunications industry. MTI’s Mobile division focus is on

design and manufacturing of state-of-the-art radio and interfacing technology components for use in 4G

and 5G mobile networks. MTI develops its technology in Taiwan, the USA and in Denmark while owning

and operating manufacturing facilities in Taiwan and China.

For requesting further details and availability of our Intellectual Property Cores solutions, contact

our sales department at sales@mti-mobile.com

For more information about MTI, visit the website http://www.mti-mobile.com/