Full-Duplex Revolution

4/17/2014 1 Proprietary and Confidential

Kumu Networks Challenging the basic assumptions of wireless networking

2

Executive Team and Investors • Two Stanford EE & CS faculty and four Stanford EE PhDs

• Augmented with industry veterans

• Top-tier investors:

Invented In-Band Full Duplex Radios • Full Duplex Breaks a Fundamental Assumption in Wireless

• Best Paper & Demo Awards at SIGCOMM 2012 and MOBICOM 2010

• Rich Patent Portfolio

• Candidate for Next Generation Wireless Standards

Proprietary and Confidential

Radios today cannot transmit and receive at the

same time on the same channel

Why Are Radios Today Half Duplex?

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TX

RX

RX

TX

Radio 1 Radio 2

Self-Interference is billions of times stronger

than the received signal

Proprietary and Confidential

Kumu Radios can transmit and receive on the

same channel!

Kumu In-Band Full Duplex Radios

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Kumu has developed a patented self-interference cancellation

technology which isolates the receiver from the transmitter

TX

RX

RX

TX

Radio 1 Radio 2

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isolator

Σ

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PA LNA

Cancellation Front-End

ANT

Modem

Transceiver

Simple addition to any radio

Existing Radio

Full Duplex Boosts Spectral Efficiency in face of slowing gains due to coding technology limits

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0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

HSPA Rel-61x2

HSPA Rel-71x2

HSPA Rel-72x2

LTE 1x2 LTE 2x2

Bit

s/Se

c/H

ert

z

Spectral Efficency Gains

1.42 1.36

1.29

1.08

0.72

Source: NGMN

The next major jump in spectral efficiency

Before getting to the handset, Full-Duplex can and

should be introduced on the infrastructure side only

• Full-Duplex is key to CoMP

interference coordination and

management

• Self-Interference Cancellation

allow LTE and WiFi to coexist

in unlicensed spectrum

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Kumu technology on infrastructure-side

Kumu’s Self Interference Cancellation is

fundamental, applies broadly beyond full duplex

Tunable RF Front End – Cure for Global Roaming

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Transmitted Self-Interference

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Channel 1 Channel 2

In-Band Full

Duplex

Double capacity

Received Signal

Adaptive

Frequency Division

Full Duplex (FDD)

Flexibly decide which

channels to transmit &

receive on

Transmitted Self-Interference

Received Signal

Channel 1 Channel 2

WiFi AP leaks significant adjacent channel noise into its

receiver, thus unable to simultaneously receive, even

on a different channel

9 Proprietary and Confidential

WiFi channels interfere with each other

Adjacent Channel Noise Buries Received Signal 60dB increase

in noise

Self-Interference Cancellation allows WiFi AP to

leverage all channels simultaneously

10 Proprietary and Confidential

Kumu cancells self-interference noise, in and out of band

Cancellation Enables the AP to Utilize All Channels

Simultaneously

LTE in unlicensed spectrum (LTE-u) would occupy one

or more channels in same frequency as WiFi

4/17/2014 11 Proprietary and Confidential

LTE and WiFi coexistance

e.g., 1800MHz e.g., 5GHz

Kumu allows LTE-u and WiFi to be collocated in

the same access point

• Likely to be very attractive

indoors, particularly in the

enterprise where RF

environment is better

controlled

• Collocated deployment with

WiFi would be desirable to

reduce equipment cost,

installation, and wiring

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Self-Intereference Cancellation betwen WiFi and LTE-u

LTE-u

Use side-band Self-Interference Cancellation in

unlicensed spectrum as a step toward Universal Radio

• Build Access Points that simultaneously use

multiple channels in the same frequency band

– WiFi and LTE-u

– Dynamic selection of ‘quiet’ channel

• Define standards to remotely configure RF front-

end of such flexible APs, ensuring interoperability

• Direct industry toward Universal RF Front-End

vision, maximizing flexibility and utilization

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Spectrum Policy Evolution

Densification is inevitable. The issue is managing

RF resources and interference.

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Organizing the airwaves

Macrocell

Picocell

Microcell

Femtocell

Interference is local. Macro coverage area natural

locality to manage interference.

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Think globally. Act locally.

Macrocell

Picocell

Microcell

Femtocell

Internet

• Tools to handle

interference have been

defined by 3GPP

– ICIC

– eICIC

– CoMP CB/CS

– CoMP JT

Macrocell

Picocell

Microcell

Femtocell

Core

Distributed MIMO (CoMP-JT) is critical for

network densification

• Coordinated Multipoint –

Joint Transmission (CoMP-

JT) tries to exploit the

interfering links to provide

capacity gains

• ICIC, eICIC, and

Coordinated Scheduling/

Beamforming (CS/CB) try

to avoid interference

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3GPP Coordinated Multipoint

Macrocell

Picocell

Microcell

Femtocell

Latency significantly reduces CoMP performance.

CoMP ideally requires 1 millisecond latency.

4/17/2014 17 Proprietary and Confidential

3GPP Coordinated Multipoint

Thro

ugh

pu

t Lo

ss

(re

lati

ve t

o la

ten

cy =

0m

s)

Source: Qualcomm

Achieving 1 millisecond latency is difficult due to

buffers in the data path, even in a fiber network

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3GPP Coordinated Multipoint

Average Latency vs. Advertised Speed - 2012

Source: FCC

Lack of uniform approach to backhauling makes it

impossible to ensure end-to-end latency

• Haphazard technology

selection

• “Direct” logical connectivity

may include switches and

routers in the physical path

• Buffers contribute to latency

– not the physical medium

• Too expense to engineer

the network for small cells

4/17/2014 19 Proprietary and Confidential

Access is standardized. Backhaul is not.

Interference management calls for new approach

to RAN control plane

• Truly DIRECT exchange between

small cells and macro cell of

Channel State Information (CSI)

from each cell to each UE

• Uniform approach to control plane

infrastructure to ensure 1ms latency

and sufficient bandwidth for CSI

• Separate high-bandwidth data plane

that continue to use any and all

available backhaul technologies

• Not another “small cell backhaul”

4/17/2014 20 Proprietary and Confidential

Separate Control and Data Plane for the RAN

Wireless link is ideal for control plane due to low latency

and direct communication between relevant entities

• Lowest possible LTE latency (1ms)

• Lowest possible UE modem cost

• Sufficient bandwidth for control (~Mbps)

• Addition to existing data plane

• Scheduler to scheduler communication

4/17/2014 21 Proprietary and Confidential

RAN Control Plan should be... WIRELESS

Self-Interference prevents devices from simultaneously

operating both as eNB and UE on same frequencies

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Why hasn’t it been implemented before?

Macrocell

Picocell

Microcell

Femtocell

eNB

eNB UE

eNB UE

UE eNB

Self-Interference

Self-Interference Cancellation key to cost-

effective low-latency RAN control plane

4/17/2014 23 Proprietary and Confidential

Small Cell

LTE Modem

DL

UL

Self - Interference

UL DL

Data Backhaul

Kumu Networks Self-Interference Cancellation

Cost-effective

Low cost UE

modem,

straightforward

networking

Low-latency

Direct connectivity

between radios

operating on same

frequency (~1ms)

Full-Duplex Relay / Self-Backhauled Small Cell

for situations where wired backhaul is unavailable

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Full-Duplex Relay

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Full Duplex Self-Backhauled

Small Cell

FDD Macro

Free Backhaul

In-Band NLOS LTE

Same channel for access and

backhaul at the same time Capacity

On-Par with a Small

Cell with Fiber

Simple to Deploy

Only Requires

Power

FDD UE No Changes

DL

UL

Self - Interference

Leverage Full-Duplex Technology on Network

side while Planning for Handset Introduction

• Decouple backhaul infrastructure of control and data planes, optimizing each for its unique purpose

• Allow backhaul of the control plane (X2) to be transported directly over low-latency LTE link

• Use full-duplex relay functionality for control channel and optionally for data channel

• Design MAC and Link layers to operate over full-duplex channel

4/17/2014 25 Proprietary and Confidential

Network Architecture Recommendations

Summary

• Full-duplex technology is the future of wireless

– Eliminate duplexing, double spectral efficiency

• Cancellation enables tunable RF front-end

– Realizing the vision of Universal Radio

• Plenty of immediate network-side applications

– Handset penetration not initially required

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Full-Duplex Revolution

4/17/2014 27 Proprietary and Confidential