Transcript Challenges on Customer Role on Distributed Agile

DYNAMIC BANDWIDTH
ALLOCATION OF OFDMA LTE
SYSTEM WITH GAME THEORY
DPS 861A
Josua Purba
Jill O'Sullivan
Raul Zevallos
Sergio Boniche
China Pankey
OUTLINE
What is Resource Management on Cellular
System ?
 Current Research on LTE Resource Management
 Research Questions
 So What?
 LTE Technology Overview
 Why use Game Theory?
 Research Methodology
 Future Research
 Conclusion

WHAT IS RESOURCE MANAGEMENT
ON CELLULAR SYSTEM ?
 What are the resources?

Bandwidth (Spectrum Frequency)
• The RF Spectrum frequency where the signal information are
sent.
• Limited in size.
• Could be 5 MHz (WCDMA), 1.4, …,5,10,20 MHz (LTE)
• Affect the rate and application run on the system
• Control the capacity of the system to handle the users

Power
• Transmit Power of Radio signal
• Can cause interference to other user/sector/cell if to big
• Different system different requirements
WHAT IS RESOURCE MANAGEMENT
ON CELLULAR SYSTEM ?

Code
• On Code Division Multiplex technique (CDMA
family, WCDMA, HSPA)
• Limited number of code
• Could not use too many code – would cause
interference, thus reduce performance.
This could make receiver more complex.
WHAT IS RESOURCE MANAGEMENT
ON LTE SYSTEM ?
Resource Management on LTE System [17]
The role of RRM is essentially to :
• Ensure that radio resources are efficiently
utilized
• Taking advantage of the available adaptation
techniques
• Serve users according to their quality of service
(QoS) attributes.
• Usually RRM handles Mobility Management

(Handover) from 1 BS to another.
WHAT IS RESOURCE MANAGEMENT
ON CELLULAR SYSTEM ?
 The mechanisms include [17]







Bearer admission control
multi-user time and frequency domain packet
scheduling
QoS-aware
Hybrid automatic repeat request (ARQ) management
link adaptation with dynamic switching between
different transmission modes.
The available transmission modes include single- and
dual-codeword transmissions for multi-antenna
configurations
Localized and distributed subcarrier transmission.
WHAT IS RESOURCE MANAGEMENT
ON LTE SYSTEM ?
BS User Plane and Control Plane Architecture
[17]
CURRENT RESEARCH ON RESOURCE
MANAGEMENT
 Spectrum pooling [10],[11]






Licensed Users (LU) share spectrum with Rental Users
(RU)
RU get the same Bandwidth size like LU
RU needs to detect LU before use the spectrum
Interference issue from RU to LU and vice versa
Works on FDMA/TDMA and OFDM system
Study the packet delay, throughput and the blocking
probability for a spectrum pooling system by using
Markov chain. [11]
CURRENT RESEARCH ON RESOURCE
MANAGEMENT?
Spectrum pooling [10]
CURRENT RESEARCH ON LTE RESOURCE
MANAGEMENT?
 Spectrum Pooling + Random Access [13]



Spectrum Pooling use Round Robin – not efficient
Combine it with Random Access to improve utilization
radio resources and improve throughput
Use Wifi for the experiment
 Heterogeneous system (TV and Wireless) [14]




Share (Sell) TV spectrum to service providers
Use double auction game theory
One between TV station and service providers
One between service providers and users
CURRENT RESEARCH ON LTE RESOURCE
MANAGEMENT?
Scheduling [21]




Classical scheduling goals in a communication
system are to maximize utilization (throughput) and
to allow communication for all users (fairness).
Study the fairness vs. efficiency on OFDMA
scheduling.
Compare various kind of game theory criteria for
cooperative bargaining.
Found Kalai-Smorodinsky solutions as alternative to
proportional fairness (Nash solution), both offer
compromise between efficiency and fairness.
CURRENT RESEARCH ON LTE RESOURCE
MANAGEMENT?
Adaptive [15]
Exploits the time diversity, frequency diversity as
well as multiuser diversity in the time, frequency
and user domain, respectively.
 Adopt a two-step allocation method to reduce the
scheduling complexity and meanwhile improve
the scheduling performance.
 Allocate users into 2 dimension frequency and
time domain like grids.

CURRENT RESEARCH ON LTE RESOURCE
MANAGEMENT?
Adaptive [15]
CURRENT RESEARCH ON LTE RESOURCE
MANAGEMENT?
Optimal Solution [9]





Investigate the issue of power control and subcarrier
assignment in a sectorized two-cell downlink OFDMA
(WIMAX) system impaired by multicell interference.
Usually with practical problem, this would not have simple
closed form solution.
Some of available bandwidth would be reused by different
base station, subject to multi cell interference.
The rest of the available bandwidth would be shared in an
orthogonal way between the different base stations, no multi
cell interference
The paper provide simpler form of general solution.
CURRENT RESEARCH ON LTE RESOURCE
MANAGEMENT?
Cognitive Radio [8]





Propose and validate a Cognitive RRM scheme in the context
of LTE network segments.
Use cognitive features that provide the system with knowledge
which observed from past interactions with the environment.
The system will be able to apply already known solutions in
timely manner when identifying a problem that has been
already addressed in the past.
Assume: all sub carrier use the same modulation type and
power level (comment: not practical)
Proposed scheme can result in significant efficiency
improvement in terms of performance and network adaptation.
CURRENT RESEARCH ON LTE RESOURCE
MANAGEMENT?
Game Theory – Auction Theory [20]




Develop theory on allocate wireless channel with
auction theorem.
Consider fair competition over independent wireless
fading channel.
each user submits a bid according to the channel
condition (assume known in the beginning time slot)
Use centralized scheduler that assign time slots
according to the Nash equilibrium strategy based on
users’ average money amount.
RESEARCH QUESTIONS
What is the optimum way to allocate bandwidth
dynamically on OFDMA LTE system with
auction theory, scheduling and cognitive radio? Is
it possible to find general optimum solution?
What is the complexity of the dynamic bandwidth
allocation with auction theorem compare to
results without game theory?
 How to apply time notion as multiple step
decision of auction theory on allocation the
bandwidth dynamically?
SO WHAT ?
 RIM CEO mention the need to conserve bandwidth
(http://www.mobilecrunch.com/2010/02/16/rim-ceo-pulls-an-att-we-need-to-conservebandwidth/)
 At the end 2009, AT&T ask its customer to reduce to
use their smart phone by giving incentive.
http://news.cnet.com/8301-30686_3-10412804-266.html
 Operator can increase the capacity and efficiency of
the network. Thus increase the revenue … bottom
line … make money and customer satisfaction
 Why LTE ?


People/customer use the technology not only research but
also commercial (real implementation)
Majority market use LTE compare to Wimax and Ultra
Mobile Broadband (UMB)
LTE OVERVIEW – KEY FEATURES
Support for, and mobility between, Multiple
heterogeneous systems:


legacy system (GSM, GPRS, EDGE, WCDMA,
HSPA)
Non-3GPP system (Wifi, Wimax, EV-DO,
satellite)
All IP Network
 Enhanced Air Interface allow increased data
rate



With Mobility: 100 MBps (DL) and 50 MBps(UL)
Stationary: 1GBps (DL) and 500 MBps (UL)
LTE OVERVIEW – KEY FEATURES
Support for higher throughput and lower
latency


User Plane Latency: < 5ms
Control Plane Latency (Transition Time to Active
State): < 100ms (from idle to active)
Increase Control Plane Capacity: > 200 users
per cell (for 5MHz Spectrum)
 Mobility Support:



Up to 500 Kmph
Optimized for low speed from 0 to 15 Kmph
LTE OVERVIEW – KEY FEATURES
Spectrum Flexibility to achieve higher
spectrum efficiency [18]:
where RB: Resource Block
LTE OVERVIEW – KEY FEATURES
Channel Bandwidth Definition [18]:
LTE TECHNOLOGY OVERVIEW
High Level Overview BS Architecture [19]
LTE TECHNOLOGY OVERVIEW
LTE scheduler on protocol stack [16]
LTE TECHNOLOGY OVERVIEW
Channel quality variations in time and freq [16]
LTE TECHNOLOGY OVERVIEW
Down Link (DL)




OFDM (Orthogonal Frequency Division
Multiplexing) use a large number of narrowband subcarrier for multi carrier transmission.
OFDM avoids the problem with multipath reflections
by sending message bits slow enough so it has high
tolerance for multipath delay spread.
OFDMA: assigning different sub channel to different
user.
Use the same principle as HSPA for scheduling of
share channel data and fast link adaptation.
LTE TECHNOLOGY OVERVIEW
Down Link (DL)

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OFDM symbols are grouped into resource block
which has 180KHz in frequency domain and 0.5 ms
in time domain.
Each user is allocated a number of resource block in
time-frequency grid.
The more resource block the higher the rate.
The scheduling mechanism control the number of
resource block at any given time.
LTE TECHNOLOGY OVERVIEW
LTE TECHNOLOGY OVERVIEW
 Up Link (UL)



Use SC-FDMA(Single Carrier Frequency
Division Multiple Access).
It adds DFT/IDFT to OFDMA architecture.
It groups the resource block in away reduce PAPR
(Peak Average Power Ratio).
LTE TECHNOLOGY OVERVIEW
 Multiple Antenna [16]


Use Multiple Input Multiple Output (MIMO) to
increase data rate, diversity, increase capacity and
beam forming.
It use 2x2 or 4x4 MIMO system.
LTE TECHNOLOGY OVERVIEW
 The DL PHY resource space for one TTI. Pilot symbols
for channel estimation purposes are not illustrated [17].
LTE TECHNOLOGY OVERVIEW [23]
LTE TECHNOLOGY OVERVIEW [23]
WHY USE GAME THEORY?
What is Game theory? [7,12]





Mathematical models of interaction between two or
more rational decision makers
Study and analysis of situations where conflict of
interests are present.
Game theory concepts apply whenever the actions of
several agents are interdependent.
These agents may be individuals, groups, firms, or
any combination of these.
The concepts of game theory provide a model to
formulate, structure, analyze, and understand strategic
scenarios.
WHY USE GAME THEORY?
Advantages of Game theory
Simplicity


Dynamic



Compare to typical math derivation
Decision made based on its condition at the time
Different decision for different condition
Distributed

Users involved in making decision
WHY USE GAME THEORY?
Limitations of Game theory
Real world conflicts are complex

Model at best can capture important aspect
No unified solution to general conflict resolution
Players are (usually) considered rational

determine what is best for them given that others are
doing the same (not cooperative)
But it can provide intuitions, suggestions and
partial prescriptions
RESEARCH METHODOLOGY
Mathematical derivation and optimization
Start from system model (still evolve)
Assumption and important parameter
Apply Game theory to system
Find optimization
Use software to help optimization
Formulize the algorithm
If time permit, simulate with software package
RESEARCH METHODOLOGY
System Model: combination cognitive radio and
game theory.
Management Infrastructure
INPUT
(Context, Profiles,
Policies)
Optimization &
Decision
(Game Theory)
LTE Network Element
(eNB, segment, cell)
Configuration capabilities
Decision efficiency
User preferences
Infrastructure
Abstraction
“Learning”
Environment
Sensing
RESEARCH METHODOLOGY
 Assumption:




One Sector, One Cell, One BS
Multiple Users (N)
With Interference and Power Control
Multiple or repeated step Auction Theory that include notion of time
 Parameter or Variable:







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
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Bandwidth size and frequency
Time
Number of User
Type of Service
Number of Resource Block
Bidding strategy
Interference (SINR)
Slot number
Rate or throughput
Number of sub-carriers
RESEARCH METHODOLOGY
Apply Game theory to system
Auction Theorem







Part of Game Theory
Definition: A public sale of property or merchandise
to the highest bidder.
Auctions have rules and bidders.
Auctioneer decides what rules to use but takes
bidders as given.
Auction mechanism tries to maximize the seller’s
revenue through the bidding of each player.
Show the supply (limited) and demand (a lot).
BS has limited resources and many users wants them.
RESEARCH METHODOLOGY
Consider the following scenarios:



Non-Cooperative (Competitive) Games: Realistic
Cooperative Games: User willing to compromise
Repeated and Evolutionary Games: dynamic scenario
Auction model:




N: number of users (i=1..N)
B: Bidding strategy (Bi= bidding strategy of user i)
P: Pay off function (Pi = Pay off function of user i)
R: Rate or throughput (Ri = Rate of user i)
RESEARCH METHODOLOGY
Auction model (continued):


K: number of sub-carrier (Ki= sub-carrier of user i)
SIR: Signal-to-Interference Ratio (SIRi of user i)
Bidding function model :



The goal is to maximize the revenue by extracting each
user’s willingness to pay about an object
I plan to use Sealed bid: bidders tell auctioneer their
bids without interacting with each other.
Sealed bid has the following rules:
 First-price. Winner pays its own bid. Losers pay
nothing.
RESEARCH METHODOLOGY

Sealed bid has the following rules (continued):
 Second-price. Winner pays highest losing bid.
Losers pay nothing.
 All-pay. Each bidder (including losers) pays its
own bid.
 Have not decided what strategy to use, but my
candidate might be Second-price.
RESEARCH METHODOLOGY
 Current auction model for throughput and fairness
analysis [22]:



Sum rate maximization
 Does not consider fairness.
 Assign sub carrier to user that has best channel condition.
Max-Min fairness
 Most strict fairness criterion since every users data rate
are equal.
 Maximize user who has lowest data rate.
Proportional fairness
 Trade off between Sum rate maximization and Max-Min
fairness.
 Maximize sum of logarithmic utility function.
RESEARCH METHODOLOGY
Proposed the new method and utility function:
 Find utility function
F = [N, K, {Bi}, Pi{.}, SIRi]
Include scheduling to equation:
Proportional fairness: Nash Solution
S = argmax Σ Ri = argmax Π Ri
 Kalai – Smorodinsky fairness algorithm
S = argmax {min (Ri / Ri max)}

Need to work the detail more in LTE
context.
RESEARCH METHODOLOGY
Key Issues in analysis
Steady state characterization
 Steady state optimality
 Convergence
 Stability
 Scalability

RESEARCH METHODOLOGY
Optimization
Find Cost function
 Cooperative, non-cooperative and repetition.
 Heuristic: Case by case

•
•
•

Case by case for few cases
Find common case or case that is used many times
Shorter time frame to develop
General Solution
•
•
•
•
The goal : find Global optimum and unique solution
Is it possible to find it on multiple step?
General case answer all possibilities
Longer time frame to develop
RESEARCH METHODOLOGY
Use software to help optimization


Use Matlab to plot the function
Find Optimum point
Formulize the algorithm in terms of steps to
LTE protocol stack procedures.
If time permit, simulate with software
package
FUTURE RESEARCH
Design and implement the algorithm using
network simulation software such as: OPNET or
OMNET
Add the fading and multipath on the analysis.
Add power control restriction on the analysis
Add case with 2 sectors, 2 cell, 2 BS and
handover as part of the analysis
Add MIMO to BS only.
Add MIMO to BS and terminals (users)
CONCLUSION
Dynamic resource allocation research is very
important as the demand for bandwidth increase
rapidly.
Different kind of methodology can be applied to
find optimum solution on dynamic bandwidth
allocation.
Many researchers use game theory for dynamic
resource allocation since it has dynamic, less
complexity and distributed characteristic.
REFERENCES
1. 3GPP Standard and Specification (http://www.3gpp.org/)
2. UMTS Forum (http://www.umts-forum.org/)
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5. Ericsson, “LTE Overview”, 284 23-3124 Uen Rev B, June 2009.
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REFERENCES - CONTINUED
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REFERENCES - CONTINUED
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