SoftRAN : Software Defined RAN

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12 Δεκ 2013 (πριν από 3 χρόνια και 4 μήνες)

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SoftRAN

: Software Defined RAN

Aditya

Gudipati

, Daniel Perry

,

Li
Erran

Li
*
,
Sachin

Katti



Stanford University

, Bell Labs
*


LTE
-

Radio Access Network

High
C
apacity
,
Uniform
C
overage
W
ide
-
Area
W
ireless Network

Client1

Client2

Client3

Client4

BS1

BS2

BS3

S
-
Gateway 1

S
-
Gateway 2

P
-
Gateway

Radio Access Network

Core Network

I

N

T

E

R

N

E

T

2

RAN Actions: Radio Resource
Management

3

1. Assign each client to a base station

time

frequency

2
. Assign resource blocks (time
-
frequency slots) to each flow

Flow 1

Flow 2

3. Assign transmit powers to be


used for each resource block

time

frequency

dB

dB

dB

dB

dB

RAN Challenges


Increasing demand on wireless resources


Dense deployments of small cells

4


Radio Resource Management
gets coupled across base stations

Coupled Radio Resource Management:
Interference


Power used by BS1
affects

interference at Client 2


Interference at Client 2
affects

power reqd. at BS2

Client1

Client2

BS1

BS2

5

Coupled Radio Resource Management:
Mobility


Dense deployments


Higher frequency of handovers


More candidate base
stations


Coordinating handovers critical

Client1

Client1

BS1

BS2

6

In dense deployments,

Radio Resource Management

needs to be
tightly coordinated

7

LTE
-
RAN: Current Architecture


Distributed control
plane


Tight coordination becomes infeasible with density


Huge demands on the backhaul network


Inefficient radio resource management


Hard to manage in a dense network

8

SoftRAN
: Big Base Station Abstraction

9

time

frequency

time

frequency

time

frequency

time

controller

Radio Element 1

Radio Element 2

Radio Element 3

Big Base Station

SoftRAN

Architecture

10

RADIO ELEMENTS

CONTROLLER

Radio

Element
API

Controller

API

Interference

Map

Flow

Records


Bytes


Rate


Queue



Size

Network

Operator

Inputs

QoS

Constraints

RAN Information Base

Radio Resource

Management

Algorithm

POWER

FLOW

Frequency

Radio Element

3D Resource Grid

Periodic Updates

SoftRAN
: SDN Approach to RAN

BS1

BS2

BS3

BS4

BS5

Packet
Tx
/Rx

OS

Control
Algo

Packet
Tx
/Rx

OS

Control
Algo

Packet
Tx
/Rx

OS

Control
Algo

Packet
Tx
/Rx

OS

Control
Algo

Packet
Tx
/Rx

OS

Control
Algo

Coordination :

X2 Interface

11

SoftRAN
:
SDN Approach to RAN

BS1

BS2

BS3

BS4

BS5

Network OS

Control Algorithm

Operator Inputs

Packet
Tx
/Rx

Packet
Tx
/Rx

Packet
Tx
/Rx

Packet
Tx
/Rx

Packet
Tx
/Rx

12

SoftRAN
: SDN Approach to RAN

13


Efficient use of wireless resources


Global
view on interference and
load



Simplified network management


Plug
-
and
-
play control algorithms

Challenges: Backhaul Latency

14

time

controller

Challenges: Backhaul Latency

15


Refactor
control plane based on
latency

-
Low
latency (
< 1
ms
)
=> No
refactoring



Principles for refactoring:

-
Controller manages
global network
state

-
Radio Elements leverage frequently
varying local
network
state

Implementation


Incrementally deployable on current
infrastructure


No modification to Base Station


client interface


New API definitions for Base Station


Femto

API: Standardized interface between scheduler
and L1 *




*
http
://
www.smallcellforum.org/resources
-
technical
-
papers

16

Future Vision


Expand
SoftRAN

to include 3G and
Wifi

networks



Coordinated management of all available
radio resources


THANKS !

17