Broadband Radio Access Networks Challenges Prof. Hamid Aghvami - - PowerPoint PPT Presentation

Broadband Radio Access Networks Challenges

• Prof. Hamid Aghvami

Centre for Telecommunications Research- King’s College London

Emerging candidates for next generation broadband radio networks (4G?)

• 3GPP LTE
• 3GPP2 Ultra Mobile Broadband (UMB)
• Mobile WiMAX

Common features among them:

• OFDM-based air interface
• Adaptive modulation and coding
• Hybrid ARQ
• Fast scheduling
• MIMO and beam forming antennas.
• IP-based access network

NAP: Network Access Provider ASN: Access Service Network CSN: Connectivity Service Network ASP: Application Service Provider NSP: Network Service Provider Source: WiMAX Forum

WiMAX Network Reference Model (NRM)

IP Based WiMAX Network Architecture

An open issue is:

How to split the radio resource and mobility management functionalities between the BS and ASN GW.

Wireless Access Network Design (In the context of end-to-end networking)

In the context of end-to-end networking ?

• End-to-end QoS
• End-to-end security
• End-to-end seamless mobility

Three main functionality groups of a wireless access network are:

• Mobility management
• QoS
• Security

Mobility Management

• The mobility management of a wireless access network includes how to solve

the problems of local seamless handover, idle mode and paging, and of course the routing capabilities within the access network that allow these to take place without constant address reassignment.

• All of these, especially the last, have major impacts on the internal architecture
• f the access network, in terms of location of functionality in different network

elements.

QoS

• The problems are:
• How to identify the specific problems of mobility and radio access impacts
• n the provision of end-to-end QoS.
• What requirements on external networks might be needed to enable QoS

mechanisms within the access network to operate.

• How to adapt QoS concepts for the fixed Internet to the mobile wireless

environment.

Security

Problems are: Within one access network

• Security interaction with mobility and QoS?
• What requirements on external networks might be needed to enable security

mechanisms within the access network to operate. Between Networks

• Networks have different identity management systems and security

requirements including confidentiality, integrity and authentication. An E2E security framework is required.

• Users are required to sign in, multiple times with different operators/accounts.

A single-sign-on is required

Combined mechanisms?

• Mobility, QoS and Security

mechanisms have traditionally been designed, each in isolation using different approaches

• When put together in one

network, the overall performance has not been as expected.

• To minimise the negative

interactions among these mechanisms, they should be designed simultaneously using the same approach and with a common signalling protocol.

Mobility Management Quality of Service Security

Challenges

• Within an access network, different design approaches have been

considered for QoS, mobility and security mechanisms in isolation without considering their inherent interactions

• Access Networks are expected to use different QoS, mobility and security
• mechanisms. To achieve end-to-end networking across them is a

challenging task.

Mobile VCE Ubiquitous Services Project

How?

• This will be done by selectively placing a number of enhanced nodes within

the network, capable of communicating with each other.

• New mechanisms will be provided to counteract the negative interactions

between QoS , mobility and security.

Mobile VCE Ubiquitous Services Project

Future Internet Access Network 1 Access Network 2 Intra access network signaling Inter access network signaling Enhanced nodes

Network layer Link Layer

Mobility QoS Security RRM

Architecture for Enhanced Nodes

S I G N A L L I N G Mobility Management Quality of Service Security

Interactions between different Modules Common signalling where possible Taking optimal decisions in a combined manner Minimising delays and signalling overhead Mobility, QoS and RRM Modules

Architecture Components

Initial study

• Major Micro Mobility solutions such as Hierarchical Mobile IPv6 propose having

Mobility Agent(s) within access networks to minimise handover signalling

• Having a node through which all packets flow through will have an effect on the

resources of the network. (i.e. increase congestion which will reduce the network throughput and the number of users the network can support)

• No work has been done to study how the presence of MAPs affect the resources

within an access network.

Introduction to the problem

Internet

Mobile Anchor Point (MAP)

Generalised View

NEXT GENERATION INTERNET

Laptop

Different mobility patterns creating different traffic demands and flows

High congestion

Network Throughput with 18 nodes

Network Throughput with 35 nodes

More challenges

• Even within a radio access network, supporting network edge-to-terminal

QoS and Security are challenging.

• QoS and security mechanisms used in the air interface and the wired part
• f access networks are different.
• To support end-to-end QoS and security, the parameters of the network

QoS and security should be mapped properly to the parameters of QoS and security mechanisms used in the MAC layer of the BS (air interface).

End-to-End QoS and Security

End-to End QoS Support in an Interworking Environment An Example DiffServ-aware priority Queuing for IP QoS Support On HSDPA

IP QoS for evolved UMTS

• IP for evolved UMTS CN/RAN.

– Low infrastructure cost. – Mitigated network administration and maintenance. – End-to-end QoS routing.

• DiffServ for IP QoS

– Packets are classified and marked to receive a particular per-hop forwarding behaviour on nodes along their path. – Sophisticated classification, marking, policing, and shaping operations need

• nly be implemented at network boundaries or hosts.

DiffServ border Data flow

IP QoS for evolved UMTS

SGSN IP-Based RAN HLR GGSN RNC BS IP-Based CN HSDPA HSUPA

• All Previously reported scheduling algorithms for HSDPA consider only
• ne queue per user.
• The scheduling is handled in the MAC layer of the Node B.
• The MAC header has 3 bits dedicated to indicate the queue ID. Thus, each

user can have up to 8 simultaneous queues in parallel.

• Each queue may be assigned a priority level. Each DSCP is mapped onto

the corresponding priority level. The packets with the same DSCP are forwarded to the correct queue.

Priority Queuing

Priority queuing (Node B architecture)

Packet distributor

HARQ signaling CQI HARQ retransmissions

HARQ #1 HARQ #2 HARQ #6

...

Tx ant. Queue #1 Queue #2 Queue #8

...

Scheduler

(MCS & MUX)

Priority queues Queues of the same priority level are treated equally.

# users

Priority queuing (UE architecture)

Reordering queue distributor

HARQ #1 HARQ #2 HARQ #6

...

MUX

Recovered data ACK / NACK CQI

SIR estimator

Feedback

MUX

Rx ant.

HARQ soft combining Reordering queues

Queue #1 Queue #2 Queue #8

...

Killer Applications and Services?

Services and Revenues

Revenue per User ( Revenue per User (£ £) )

0.10 0.10 0.20 0.20 0.30 0.30 0.40 0.40 0.50 0.50 0.60 0.60 0.70 0.70 0.80 0.80 0.90 0.90 1 1 2000 2000 1000 1000 500 500 1500 1500 750 750 250 250 1250 1250 1750 1750

Throughput/Performance Requirement (Kbps) Throughput/Performance Requirement (Kbps)

On-line gaming Game downloads Video/TV streaming MMS Text Messages Music Web browsing Email Video phone Paid applications Paid services

Source: BT Technology Journal

Trends in media creation/consumption

Source: COMSCOR, JUNIPER RESREACH

Thank You

Any Question?