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

WiMAX Network Reference Model (NRM) NAP: Network Access Provider ASN: Access Service Network CSN: Connectivity Service Network ASP: Application Service Provider NSP: Network Service Provider Source: WiMAX Forum

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 of 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 on 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 Mobility Management 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 Security common signalling protocol. Quality of Service

Mobile VCE Ubiquitous Services Project 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.

Architecture for Enhanced Nodes Mobility QoS Security RRM Network layer Future Internet Link Layer Access Network 2 Access Network 1 Inter access network Enhanced nodes Intra access network signaling signaling

Architecture Components Mobility Management S I G Mobility, N QoS and Interactions A Quality of Service RRM L between L Modules different Common I Modules N signalling G where possible Security Taking optimal decisions in a combined manner Minimising delays and signalling overhead

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 High congestion Laptop Different mobility patterns creating different traffic demands and flows

Network Throughput with 18 nodes

Network Throughput with 35 nodes

End-to-End QoS and Security 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 of 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 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 only be implemented at network boundaries or hosts. DiffServ Data flow border

IP QoS for evolved UMTS HLR HSDPA IP-Based CN HSUPA IP-Based RAN RNC SGSN BS GGSN

Priority Queuing • All Previously reported scheduling algorithms for HSDPA consider only one 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 (Node B architecture) CQI Priority Tx ant. # users queues HARQ Queue #1 signaling Packet distributor Queue #2 Scheduler (MCS & MUX) HARQ #1 ... Queue #8 HARQ #2 ... HARQ #6 Queues of the same priority level are HARQ treated equally. retransmissions

Priority queuing (UE architecture) Feedback MUX ACK / NACK CQI Rx ant. SIR HARQ #1 Queue #1 Reordering queue estimator distributor HARQ #2 Queue #2 MUX Recovered ... ... data HARQ #6 Queue #8 Reordering HARQ queues soft combining

Killer Applications and Services?

Services and Revenues 1 1 Text Messages 0.90 0.90 Paid applications 0.80 0.80 Web browsing ) £) Revenue per User (£ 0.70 0.70 Revenue per User ( Email 0.60 0.60 Game downloads 0.50 0.50 Video/TV 0.40 0.40 streaming MMS Paid services 0.30 0.30 Video phone Music 0.20 0.20 On-line gaming 0.10 0.10 0 0 250 250 500 500 750 750 1000 1000 1250 1250 1500 1500 1750 1750 2000 2000 Throughput/Performance Requirement (Kbps) Throughput/Performance Requirement (Kbps) Source: BT Technology Journal

Trends in media creation/consumption Source: COMSCOR, JUNIPER RESREACH

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