arq proxy (for wifi networks) ischia island, italy sept. 11, 2007 dzmitry kliazovich nadhir ben...

ARQ Proxy(for WiFi networks)

Ischia island, ItalySept. 11, 2007

Dzmitry KliazovichNadhir Ben Halima

Fabrizio Granelli

University of Trento, Italy

Dzmitry Kliazovich ([email protected])Sept. 11, 2007

TCP over Infrastructure WiFi

LL-ACK

TCP Data

Mobile Node(MN)

Base Station(BS)

Channel Contention

Channel Contention

LL-ACKTCP ACK

WiFi (IEEE 802.11)IP Network

TCP DataPHY

HeadersLL

Headers

TCP ACKPHY

HeadersLL

Headers

Legend:

Transmitted at Basic rateTransmitted at Data rate

ApplicatioApplication Datan Data

AcknowledgementAcknowledgements at different s at different

layerslayers


ARQ Proxy - Approach

Idea: Substitute the transmission of TCP ACK packets with a short MAC layer request on the radio link for multilayer ARQ overhead reduction


ARQ Proxy - Approach

TCPData

PHY /LLHeaders

LL-ACK

Fixed Host(FH)

IP Network

ARQ Proxy MAC ARQ ClientMAC TCP

TCP Data

Mobile Node(MN)

Base Station(BS)

TCP

o Access TCP header

o Get IP addr, port, etc.

o Generate TCP ACK & store

o Compute TCP ACK identification index

GenerateTCP ACK

TCP ACKIndex

TCP Data

TCP ACK

TCP ACKIndex


ARQ Proxy – Packet Identification Hash values Frame Sequence Numbers

Mobile Node(MN)

Base Station(BS)

LL-ACK

Hashfunction

PHYHeader

LLHeader

TCP data

Input Hash Value

DCF53473

Octets:

FrameControl

Duration RA FCS

2 2 6 4

Bit 15 Bit 14 Bit 13-0 Usage

0 0 - 32767 Duration

1 0 0 Fixed value during CFP

1 0 1-4096 TCP ACK index

1 0 4097-16383 Reserved

1 1 0 Reserved

1 1 1-2007 AID in PS-Poll frames

1 1 2008 - 16383 Reserved

PHYHeader

LLHeader

TCP data

SequenceControl

Address 3 Address 4

FragmentNumber

B3 B4

Bits: 4 12

B15B0

Sequence Number

Link layer ACK (LL-ACK)

oror


ARQ Proxy - Benefits

Performance and System Capacity Increase

LL-ACK

TCP Data

Mobile Node(MN)

Base Station(BS)

Channel Contention

Channel Contention

LL-ACKTCP ACK

WiFi (IEEE 802.11)IP Network

TCP DataPHYHeaders

LLHeaders

TCP ACKPHYHeaders

LLHeaders

Overhead Overhead reductionreduction



Reduced RTT (Round Trip Time)

Fixed Host(FH)

IP Network

Mobile Node(MN)

Base Station(BS)

TCP Data

TCP ACK

Medium Access + TCP ACK Medium Access + TCP ACK Transmission over wireless Transmission over wireless

channelchannel



End-to-end TCP semantics are maintained

Fixed Host(FH)

IP Network

Mobile Node(MN)

Base Station(BS)

TCP Data

TCP ACK LL-ACK



Higher channel error rates tolerance

Fixed Host(FH)

IP Network

Mobile Node(MN)

Base Station(BS)

TCP ACK

No TCP ACK over wireless No TCP ACK over wireless channelchannel

Wired channel(BER = 10-6 to 10-

8)

Wireless channel(BER = 10-3 to 10-

1)



Mobility & Incremental deployment

Fixed Host(FH)

IP Network

Mobile Node(MN)

Base Station(BS)

No TCP state related

information is maintained

ARQ Proxy ARQ Client



Performance and system capacity increase Reduced RTT (Round Trip Time) End-to-end TCP semantics are maintained Higher channel error rates tolerance Full mobility support Incremental deployment & Co-existence


ARQ Proxy - Limitations

TCP ACKs are not substituted: During connection establishment and

connection termination packets (identified by SIN and FIN flags)

For TCP ACK encapsulated into TCP data packet in case of bidirectional data transfer

For Duplicate TCP ACKs TCP ACK advertising exhausted receive buffer

resources (rwnd field)


Evaluation Results

Simulation Setup Ns2 simulator with ARQ proxy extensions IEEE 802.11b physical layer, no RTS/CTS Bottleneck buffer: 700 packets TCP NewReno flows Results averaged over 10 runs

Fixed Host Mobile NodeBase Station

100 Mb/s, 15 ms

IEEE 802.11b @ 11 Mb/s

ARQ Proxy ARQ Client


Evaluation Results

Throughput performance

0 300 600 900 1200 15000

1

2

3

4

5

6

TCP/IP datagram size (Bytes)

Th

rou

gh

pu

t (M

b/s

)

ARQ proxy ONARQ proxy OFF

Improvement: 20%

Improvement:up to 100%

VoIP and MultimediaApplications

TCP file transfer, Ethernet MTU


Evaluation Results

Round Trip Time (RTT) improvement

0 10 20 30 40 500

10

20

30

40

50

60

Simulation time (seconds)

Sm

oo

th R

TT

(m

sec)

ARQ proxy OFF

ARQ proxy ON

Order of millisecond

s


Evaluation Results

High error rate tolerance

0 0.05 0.1 0.15 0.2 0.25 0.3 0.350

1

2

3

4

5

6

7

Packet Error Rate (PER)

Th

rou

gh

pu

t (M

b/s

)

ARQ proxy ONARQ proxy OFF


Motivation for Scenario Choice Why link layer ARQ as a feedback

channel?

Why TCP? Accounts for more than 85% of Internet traffic*

Why Infrastructure network scenario? Over 95% of wireless links are on the last mile

[*] C. Fraleigh at el. “Packet-level traffic measurements from the Sprint IP backbone,” IEEE Network, vol. 17, no. 6, pp. 6 – 16, Nov.-Dec. 2003.


Other Operation Scenarios

Single-hop Ad hoc network

Fixed NetworkInfrastructure

Fixed Source

. . .

Multi-hop network

Infrastructure network with relays

ARQ ProxyARQ ProxyARQ ProxyARQ Proxy

ARQ ProxyARQ Proxy


ARQ Proxy for 3G LTE

Key features Evolved radio access: OFDM,

multiple antenna techniques Evolved architecture: fewer

nodes, reduced latency, low cost

Evolved networking: All-IP architecture, shared resources

BTS

SGSN

NodeB

eNodeB

HSS

BSC

RNC

GERAN

UTRAN

Evolved RAN

GPRS Core

MMEUPE

non 3GPPIP Access

WLAN 3GPPIP Access

Evolved Packet Core

IMS, PSS, etc.

PCRF

SAEAnchor

3GPPAnchor

3G Long-Term Evolution (LTE)


ARQ Proxy for 3G LTE ARQ Proxy: Use Hybrid ARQ (HARQ) feedback to

substitute TCP ACK packets on the radio channel Hash values for packet identification

TCP

MAC

TCP Data

TCP ACK

ARQClient

HARQACK+

ACKGeneration

Outputqueue

Sniff

TCPACKHash value

HARQ

Protocol stack at the receiver


Evaluation: 3G LTE scenario Setup

Ns2 with Enhanced UMTS Radio Access Extensions (EURAE)

eNB and RNC are combined into a single node Rayleigh fading with 300 meters between UE and eNB Encapsulation overhead: TCP (20 bytes), IP (20 bytes),

PDCP (1 byte), RLC (2 bytes), and PHY CRC (2 bytes) Hash value size: 32 bits TCP NewReno sources

Metrics Throughput and Round Trip Time (RTT) performance with

different error rates


Evaluation: 3G LTE scenario Round Trip Time

(RTT)

0 20 40 60 80 1000

10

20

30

40

50

60

70

80

90

Simulation time (s)

RT

T (

ms)

TCPTCP + ARQ Proxy

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Hash error rate

Ave

rag

e T

CP

Th

rou

gh

pu

t (M

b/s

)

Hash value errors


Current Activities and Future Work ARQ proxy material (Available)

ARQ proxy for WiFi (IEEE 802.11)

ARQ proxy for 3G LTE (Super-3G)

EU patent-pending• D. Kliazovich, F. Granelli, S. Redana, and N. Riato, “Cross-Layer Error Recovery Optimization for 3G LTE Systems,” EP 07425087.9

• D. Kliazovich, F. Granelli, S. Redana and N. Riato, “Cross-Layer Error Control Optimization in 3G LTE,” IEEE Global Communications Conference (GLOBECOM), Washington, DC, U.S.A, December 2007.


Current Activities and Future Work ARQ proxy material (Coming soon…)

ARQ proxy for WiMAX (IEEE 802.16) Adaptation and system level simulations

Proposal to 3GPP standardization group

Under consideration for next generation equipment produced by Nokia Siemens Network (NSN)


Thank you!

arq proxy (for wifi networks) ischia island, italy sept. 11, 2007 dzmitry kliazovich nadhir ben...

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