Broadband Fixed Wireless Access: Status Review

1
Broadband Fixed Wireless AccessStatus Review
Research Issues

• Nikos B. Pronios, PhD
• Manager
• Development Programmes Dept.
• npro_at_intracom.gr

2
Presentation outline

• Wireless Mobile systems
• Spectrum availability
• BFWA System evolution Standardization
• ADAMAS
• STINGRAY
• Research Issues

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Mobility and Bit Rates
New Broadband Wireless Access Application
Broadband Fixed Wireless Access
????802.11a
User Bit Rates
Source ETSI/BRAN
4
Next Generation Network Structure
Clients Applications
5
A Systems B3G Scenario
Application server
Mobility Agents
SIP servers
Application server
HLR/VLR
HLR-AAA Gateway
Operators Servers


3G IP backbone
AAA Server
Firewall

Router
Other Broadband Wireless Access
GGSN
UTRAN
Hotspot WLAN
6
Global spectrum status
Source ADAMAS, http//adamas.intranet.gr
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Broadband FWA roadmap technologies
Max Data Rate (log scale)
45 Mbps
LMDS
30 Mbps
New Broadband Wireless Access Application
25 Mbps
20 Mbps
Wireless IP
10 Mbps
One-way Digital MMDS
Two-way Digital MMDS
2 Mbps
One-way Analogue MMDS
256 Kbps
WLL
Year
2003
2000
1995
1998
2005
Source INTRACOM 2001
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Broadband FWA Evolution
Max. Data Rate
25 Mbps
10 Mbps
256 Kbps
2002 ...
1999 - 2001
1995 - 1999
FP5
FP6
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BFWA Environments of Operation Current
Standards

• BFWA Systems lt 11 GHz
• IEEE 802.16a
• ETSI/BRAN HIPERMAN
• Near LOS and NLOS conditions
• Path Loss
• Multipath effects
• Partial blockage by foliage
• Reflections
• Fading characteristics
• Ricean or Rayleigh distribution
• Excess delay spread few µsecs

• BFWA Systems gt 11 GHz
• IEEE 802.16
• ETSI/BRAN HIPERACCESS
• LOS conditions
• Path Loss
• Attenuation
• Atmospheric
• Rain, Snow
• Fading characteristics
• Ricean distribution
• Excess delay spread several hundreds nsecs

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BFWA Standardization System Characteristics
MIMO/ MISO Space, Time frequency opt.
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ADAMAS Standardization timeline
Frequency (GHz)
40
ETSI/BRAN HIPERACCESS
IEEE 802.16
26-28
IEEE 802.16.2
5.8
3.5
04/02
Time
03/99
09/01
9/99
3/00
12/02
11/02
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ADAMAS Objectives

• ADAptive Multicarrier Access System
• Adaptive OFDM P-MP outdoor fixed broadband
  wireless system for
• Unlicensed scenario (5.8 GHz)
• Licensed scenario (10.5 GHz)
• Variable service symmetry from full asymmetric to
  symmetric services
• DTDMA
• Cost reduction and efficient utilization of
  frequencies
• TDD

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ADAMAS System Requirements

• Operation in LOS, PLOS and NLOS conditions
• Operation in licensed and unlicensed environments
• Support for many users within a geographical area
  and for a given BW
• Adaptivity in both PHY and DLC layer
• Radio channel variations
• Traffic variations
• Support for different services

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Definitions on PHY adaptivity

• Coarse Adaptivity (Mandatory)
• Corresponds to per user adaptivity with different
  modulation/coding combinations for DL and UL
  periods (bursts)
• Fine Adaptivity (Optional)
• Corresponds to per subcarrier adaptivity within a
  burst
• Evaluated schemes reasonable for NLOS scenarios
• Adaptive bit-loading per subcarrier group (SBLA)
• Adaptive power loading
• Weak subcarrier excision
• Nulling (erasure decoding)
• The final choice of Nulling was a trade-off
  between improvement vs. system complexity

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Coarse adaptivity thresholds

• SNR is reported to DLC with 0.5 dB granularity
• Software adjustable SNR margin in steps of 1 dB
  is supported

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Fine PHY adaptivity comparison
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ADAMAS DLCTime Frame Structure Motivation

• Limited number of time slots in the TF
• Minimize FCP/BCCH overhead
• High bandwidth utilization
• Dynamic TDD/TDM-TDMA scheme
• In the DL (TDM), TSs are grouped to domains
  according to their radio link quality
  characteristics (i.e. modulation and coding
  scheme)
• The UL (TDMA) data region is organised on a per
  connection basis.

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Demonstrator Implementation
Antenna
RF Indoor Unit
PRI
RS-232
SDRAM
Outdoor Unit
RJ-45
D Connector
USB
E1/T1 Ports
E1/T1 Module
DLC Board
Pentium III
H.110
Baseband Board
IF and data cables
cPCI
cPCI Backplane bus
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Demonstration scenario
E1 Analyzer
LoopBack
Voice Traffic Generator
monitor PC
Tx Rx
ADAMAS
E1
E1
IP
IP
RF
Network Analyzer (optional)
RF
Client
Web Server
Web Server
Client
monitor PC
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Baseband Board

• FPGA
• Xilinx Virtex II
• DSP
• TMS320C6416
• PCB
• 6 layers signals
• 4 layers power lane

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Daughter board top view
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RF Indoor Unit Layout
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Space Time Frequency Coding Example
Multiple Transmit-Receive Antennas OFDM Systems
OFDM
Space-Time-Frequency Encoder
Information Source
Receiver
OFDM
Space
Time
Frequency
Source STINGRAY, http//stingray.intranet.gr
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STINGRAY Technology timeline
Space Time codING for Reconfigurable wireless
Access sYstems
STC introduction By Tarokh
Transmitter Diversity OFDM by Li
Capacity limits Using MEA tech. By Foschini
Contribution STCOFDM In IEEE802.16.3 By Hughes
STC OFDM By Tarokh
Foschini Layered Architecture
03/98
07/99
10/98
07/00
09/96
01/02
01/01
MEA Multi Element Array Technology
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STINGRAY Objectives

• To develop STC for OFDM Broadband Fixed Wireless
  Access System
• To design establish the adaptivity and
  reconfigurability criteria for the targeted
  STC-OFDM system
• To design and implement reconfigurable OFDM-STC
  modules
• To develop a MIMO channel model based on
  conducted measurement campaign
• To upgrade the existing OFDM SISO platform to
  MIMO
• To integrate the reconfigurable modules into the
  existing platform
• To develop channel emulator

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Rationale Novelties

• Generalization of an option (Alamouti) that has
  recently appeared in the standardisation
  activities.
• HIPERMAN includes MISO ONLY
• STC OFDM schemes
• Currently, SC schemes were studied, no frequency
  selective channels are explored accompanied by
  multicarrier
• Reconfigurability
• New techniques will be explored
• DPR
• Adaptivity
• Adaptive coding schemes (coding rates,
  interleaver sizes)
• Adaptive modulation (Per user, Per subcarrier,
  tradeoffs with various FECs)

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Adaptive vs Reconfigurable

• Reconfigurable
• Is a system with the capability of rearranging
  the blocks and the interactions among them for
  supporting different functionalities.
• Adaptive
• Is a system with the capability to vary its own
  parameters, by for example close-loop actions,
  and to improve its performance (usually it
  monitors its own performance)

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Reconfigurability

• Static
• The FPGA will be placed off-line, a new
  configuration file. Any data inside the device
  are lost after the reconfiguration.
• Dynamic
• The device can be re-configured on-line.
  Potentially the device can keep doing part of its
  assigned task, and retain some of its internal
  data.
• Dynamic Partial
• Only parts of the device is re-configured
  on-line. The other parts operate unhindered, and,
  potentially, the device can keep doing part of
  its assigned task, and retain some of its
  internal data.

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Reconfigurability in STINGRAY

• Benefits of FEC reconfigurability in STINGRAY
• Best required performance (BER and throughput)
  for minimum processing
• Benefits of STC reconfigurability in STINGRAY
• Depending on the existence and quality of CSI we
  may want to switch between channel blind STC
  (e.g. Alamouti) and channel aware STC (e.g. TSD
  or SVD)

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Alamouti vs TSD
.
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Current view of STINGRAY demonstrator
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STINGRAY Demonstration Transmitter
Input Logic
FEC
Constellation Encoder
CRC
Scrambler
Multiplexer
Preamble Generator
Baseband Control
Space-Time Encoder
Multiplexer
IFFT
Adaptivity Control
To RX
Pilot Generator
Multiplexer
IFFT
Background
STINGRAY modules
Cyclic Prefix Insertion
Output Logic
Mapper
Adaptive
Reconfigurable
Cyclic Prefix Insertion
Output Logic
Mapper
Adaptive and/or Recoonfigurable
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BFWA System requirements currently under
Development

• High Bit rates
• High Capacity/Spectrum Efficiency
• High Coverage, Service Availability and
  Scalability
• Integration with 3G
• Cost

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Research Topics in BWA

• Portability within service area of BWA providers
• Interoperability / convergence of broadband FWA
  systems and broadband mobile systems (3G, B3G)
• Co-existence, spectrum coordination
• Automatic and dynamic frequency planning
• Sharing of frequencies among different systems
• Antennas
• Diversity (space and polarization)
• Adaptive antennas
• Space,Time Frequency Coding
• Self/re-configurable and Adaptive systems
• Network deployment architectures
• Mesh networks vs P-MP, ad-hoc networking
• Macrocell / Supercell

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A Layered Architecture for Minimum Delay
Wide-Area Ad-Hoc Networking
IP related protocols (Ad-Hoc, routing, mobility)
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Conclusions

• BWA systems is an attractive solution
• For areas without much existing infrastructure
• If cost is reduced and ease of deployment is
  increased
• Research issues are open, in particular for
• Spectrum re-use with mobile systems
• New architectures
• Mesh networks vs P-MP, ad-hoc networking
• New air interfaces, including antennas
• Single-universal vs use best available for the
  application
• Re/self-configuration