As computing and communications converge, network BW must follow CPU & memory size….
Radio Technology: Moore’s Law applies to wireless! 1990 1995 2000 Year 1 10 100 1000 Mhz 1 10 100 1000 Kbps 1 10 100 1000 Mbps 1 10 100 1000 MB LAN/WAN Switching Local Access CPU Speed Memory Size CPU LAN/WAN Local Access Memory Kbps 1 10 100 1000 Wireless Access Wireless CDPD 3G Mobile 802.11bWLAN, Cable Modem DSL Gbps Router ATM 56K modem Sw Ethernet 802.11a, UWB,.., short-range radio speeds outpacing Moore’s law over last ~5 yrs!
Radio Technology: Modem Evolution QPSK/GMSK Equalized QPSK/QAM/ GMSK,.. Multicarrier Modulation (OFDM, etc.) Spread Spectrum (CDMA) Multiple antenna spatial processing (MIMO, etc.) Wideband CDMA (w/ interference canc. & multiuser det) IS-136, etc. DVB, 802.11a, etc.. US HDTV, WLL, 802.11b IS-95 4G and next-gen WLL ~10-100 Mbps depending on cell size & mobility ~5-10 bps/Hz achievable with QAM UMTS/IMT-2000 ~2 Mbps depending on cell size ~0.5 bps/Hz typical for proposed systems (works at vehicular mobility speeds) Time/Frequency processing Time/Frequency + spatial processing UWB WPAN and WLAN ~100-500 Mbps no allocated spectrum no RF carrier short-range, high-data rate Pulsed communication
Example opportunistic transmission scenario: : vehicular user passes by an “Infostation” Short-range radio channels W z d trajectory Offset w
Initial results show that channel is well-behaved for distance ~5m 100’s of Mbps readily achieved with various modem techniques Data from Domazetovic & Greenstein  Short-range radio channel
Radio Technology: UWB Source: J. Foerster, Intel Research, 2001 Pragmatic bit-rate comparison between UWB and 802.11x options “ sweet spot” for use as nx100 Mbps WPAN UWB appropriate for energy-efficient radio links, typically short-range Also has potential hardware complexity advantages...
Radio Technology: Hardware Innovations
As wireless modems become faster and more ubiquitous, key hardware innovations urgently needed:
compact RF components, including MEMS
mixed signal design & testing
silicon integration and packaging
UWB radio architecture
software-defined radio @ 10-100 Mbps
integrated wireless sensors (low-power)
Wireless Systems: Research Topics
Designing and optimizing wireless systems via radio resource management (power control, interference avoidance, scheduling, etc.)
Selected research topics in the wireless systems area include:
scaling cellular system capacity
scaling ad-hoc network capacity & throughput per user
radio resource management for 3G and ad-hoc nets
spectrum sharing in unlicensed bands
Rapidly increasing use of untethered data devices implies that wireless access network capacity (bps/sq-Km) will soon have to scale to “gigabit” levels...
Wireless Systems: Increasing the scale of networks Internet Wireless Access Networks Mobile Comm Devices Fixed PC/WS Mobile PDA/PIA Semi-mobile Laptop, etc. Growing proportion of all computing devices --> 50% +? Telecom Network Sensors/ low-tier data Example : ~10,000 devices/sq-Km @1 Mbps peak and 0.1 Mbps avg implies system capacity ~Gbps/sq-Km
Consider first the scaling limits of existing and emerging wireless network standards...
max capacity ~ 100 Mbps avg, 1 Gbps peak per sq-Km
correct order-of-magnitude, but too many access points & limited mobility
Wireless Systems: Increasing the scale of networks
Wireless Systems: Architecture Evolution Mobile/Wired Network GW Cellular Macrocell (~5-10 Km radius) Custom wireless protocol Standard IP, ATM, etc. 2G/2.5G/3G radio access (single standard) Gigabit Metro Area Network (w/ integrated mobility support) BTS AP/ mini-BTS WLAN+ or “4G” or new radio access (multiple standards) Standard IP + M interface Regulated spectrum, static freq co-ord Unregulated spectrum, dynamic freq coordination Faster radio PHY’s with high interference rejection & bps/Hz efficiency IP end-users 2G/3G end-users Mbps/Km2 Gbps/Km2 Current Wireless Network Scalable Heterogeneous Pico/Micro/Macrocellular Wireless Network Model Static provisioning Dynamic provisioning/ QoS Radio Microcell (~0.5-1 Km radius) Location-aware information services, mcast, cache, etc. WAP services. etc. High-speed radio hot spot Radio macrocell WPAN WLAN Microcell (~100m radius) IP end-users
Wireless Systems: RRM Model for Cellular systems
Multiple cell scenario with desired and interfering signals
Algorithms for allocation of bit-rate, base station, channel, tx schedule, power
Common theme: reduce interference, transmit when the channel is “good”
Source: Prof. R. Yates, Rutgers U BS k BS 1
Wireless Systems: RRM in 3G – adaptive incremental redundancy example Source: Dr. L. Razoumov, Rutgers U
Scaling of wireless services will need new spectrum (~Ghz) particularly for new high-speed data services
Need to rethink traditional approach to spectrum regulation
More unlicensed spectrum (e.g. 5 Ghz U-NII)
Market mechanisms other than one-time spectrum auctions?
Spectrum etiquette procedures for coexistence of QoS-based wireless services (beyond “LBT”)
Incentives for efficient utilization of spectrum resources?
Relationship to property rights?
Wireless Systems: Efficient Spectrum Use
Spectrum etiquette procedure a key issue for U-NII scenario
“ CSCC” approach proposed as possible solution...
Coordination channel using simple standard protocol at edge of band
Semantics of higher layer coordination protocol TBD...
Support arbitrary spectrum policies based on user priority, cost bids, etc.
Wireless Systems: Efficient Spectrum Use Common Spectrum Coord Channel (CSCC) Channel: #1 #2 #3 #4 #5 #6 #N ..... .... .... Packet service Streaming service A Streaming service B Periodic announcements incl..: Service type, User #, Channel #, service params, Priority, Cost/Price Bids, etc.
Wireless Systems: Efficient Spectrum Use Example of CSCC etiquette used for “dynamic pricing” based spectrum allocation: channel CSCC channel Price Bid $.07/hr f n f n f n f n Price Bid $.09/hr A B B contends for f n A raises bid on f n … e-cash exchange ? A A B User ID Service Type Price Bid $.05/hr A wins contention ( B records & reports transaction!)
Mobile Networks: Some Research Topics
Selected research topics in the mobile networks area include:
new MAC protocols: 802.11x, 803.15.x, sensor nets
“ 4G” network architectures
mobility protocols: beyond mobile IP
new architectures (WLAN hot-spots, Infostations, ..)
self-organizing wireless networks (sensors, etc.)
ad-hoc network routing
multicasting and mobile content delivery
wireless network security
Mobile Networks: “4G” Protocol Evolution WPAN radio Today’s Wireless Systems The Future Low-tier services IP 802.11 Radio Ethernet Mobile Service Middleware IP WLAN Services 3G/4G Radio WLAN radio WPAN/low- tier radio 2.5G/3G Radio GSM/ GPRS 2.5G/3G Services 3G Access Network PSTN IP WPAN network layer (e.g. Bluetooth) Generic Radio Access Network Radio-specific vertically integrated systems with complex intetworking gateways Security QoS VPN Content Delivery 4G Services Radio Independent modular system architecture for heterogeneous networks uniform radio API’s generic network API uniform service API (Internet+) Unified IP-based mobile network incl support for multihop, mcast, etc, service feature modules
Mobile Networks: Protocols beyond mobile IP Radio Access Network 1 Global Internet Mobile IP overlay network radio bridge/ router (forwarding node) access point
Mobile IP provides a permanent IP address
for users moving between wireless AP’s
Desired RAN features for ad-hoc WLAN,
sensor nets, 4G:
handoff support (micro-mobility)
discovery and self-organization
ad-hoc routing, integrated with MAC
multicast, QoS, security, etc.
closer layer 2/3 coupling needed
IP extensions or generalized L2 MAC??
Mobile Networks: 3G/WLAN interworking Techniques for seamless service: - Authentication, global roaming - Security issues - Dynamic handoff - End-to-end QoS control - Network management - Service level agreements Bluetooth<-> 3G IWF WLAN<->3G IWF Bluetooth UWB, Bluetooth<->WLAN IWF WLAN, HiperLAN, UWB, Cellular/2.5G,3G 3G/WLAN interworking Unified Mgmt Layer Protocol stacks PHY link net IWF1 IWF2 BT WLAN 3G Multiple devices with various radio interfaces
Mobile user passes through hot-spot (Infostation) in sec during which ~MB files are downloaded/uploaded
Requires modifications to conventional WLAN MAC, incl fast synch, pre-authentication, etc.
Motivates 2-tier arch with ~10m service zone (for high-speed data transfer) and ~50m access control zone
Transit time ~sec Infostations access point Data cache ~100 MB/s Fast transfer Low-speed control channel (for synch & service setup) Service Zone Access Control Zone Total transit time ~10sec Mobile Networks: Hot-Spot MAC
802.11a MAC can be used for opportunistic service
Pre-authenticate user in low-bit rate mode (~50m range)
Mobile terminal waits for modem to reach max 54 Mbps (~10m range)
High priority access mode used for Infostations access
Mobile Networks: Hot-Spot MAC AP Beacon IS Control packet Terminal enters WLAN coverage area Mobile requests advance authentication ........ Authentication message exchange PIFS normal channel activity .. IS transfer request* PIFS Infostations file transfer* Terminal enters max PHY speed zone ACK A1 A2 A3 Priority Access initiated *RTS/CTS msgs not shown time
New real-time, context- and location-aware information delivery paradigms under consideration ...
Content multicasting based on XML investigated as possible option for delivering relevant info to mobiles.
Mobile Networks: Content Multicast SX SX Content Provider Semantic Router A Semantic Router B Interest profile Mobile interest profile contains: (user, location, terminal capability,..) content multicast User XML Descriptor
A flexible, open-architecture mobile/ad-hoc sensor network testbed recently established at WINLAB
open-source Linux routers and AP’s (commercial hardware)
Linux and embedded OS forwarding and sensor nodes (custom)
radio link and global network monitoring/visualization tools
Mobile Networks: Experimental Research PC-based Linux router Router network with arbirtrary topology AP Compute & storage servers Management stations Radio Monitor Forwarding Node/AP (custom) Sensor Node (custom) 802.11b PDA 802.11b Linux PC Commercial 802.11
Wireless Research: Multidisciplinary Research Topics
In conclusion, we mention some wireless-related multidisciplinary research topics: