Wireless Communication Networks

ENEE 723

FALL 2004


Time/Venue

TuTh 12:30 -- 1:45 EST
Room ITV 1111 (Instructional Television Building)

Instructor


Prakash Narayan
Room AVW 2353
(301) 405 3661
Fax: (301) 314 9281
E-mail: prakash@eng.umd.edu

Office hours

Tu 4:30 - 5:45 pm EST
Th 2:00 - 3:15 pm EST
Also by appointment

Course objectives

To provide a general understanding of the basic principles
which govern the design and operation of wireless communication
networks, with emphasis on the wireless link, media access control
and interference issues. We begin by considering the cellular
architecture model, frequency reuse, power control, handoff
and mobility tracking. We then consider wireless local area
networks, including a review of recently proposed standards. 
Next, ad hoc networks will be studied with a focus on
routing/multicasting and \lq\lq capacity" notions. Principles of
of layer integration and energy efficiency will also be
addressed. The special cases of sensor networks and satellite
systems will be reviewed.

Prerequisites

A mastery of Random Processes in Communication and Control
(ENEE 620 or equivalent) and Multiuser Communication (ENEE 625 or
equivalent) is expected. Further, a sound knowledge of Information
Theory (ENEE 721 or equivalent) will make all our cups runneth over.

Course grade

The final grade for the course will be determined by a student's
performance in
  • a midterm in-class written examination (30%);
  • a term project (10% for proposal, 20% for final oral presentation and 40% for final written report).
The midterm examination will be held in the last week
of October 2004 (sufficient
advance notice of the exact date will be provided).
The term project will have three components:
  1. a written proposal (due in the last week ofOctober 2004); 
  2. an oral presentation (in the last week of class);
  3. a written project report (due on December 13, 2004).
Details will be provided later.

Please note: There will be no written in-class final examination on
December 18, 2004.


Announcement

  • Midterm examination:  Tuesday, Nov. 9, 2004

Planned course topics

1. Introductory concepts

  • Wireless medium (models, properties)
  • Multiaccess channel
  • Medium access control
  • Interference and quality of service.

2. Cellular networks

  • Basic architecture
  • Frequency reuse
  • Power control
  • Mobility control - handoff
  • Dynamic channel assignment
  • Registration, paging, mobile IP.

3. Wireless local area networks

  • Comparisons and contrasts with (ordinary) LANs
  • Bluetooth
  • IEEE 802.11
  • Infrared systems.

4. Ad hoc networks (multihop)

  • Notions of "link" and "graph"
  • Layer interaction
  • Routing/multicasting
  • "Capacity" notions.

5. Energy efficiency

  • Forms of energy consumption
  • Effects of power control, MAC and routing/multicasting
  • Limited energy supply.

6. Sensor networks

  • Objectives and architectures
  • Energy concerns
  • Design approaches.

7. Satellite networks

  • Modern satellite systems
  • Onboard processing capabilities
  • Satellite constellations
  • Hybrid networks -- design and performance.

Reading Assignments

1.  R. L. Cruz and A. V. Santhanam, ``Optimal Routing, Link
     Scheduling and Power Control in Multi-hop Wireless Networks''

2.  A. E. Gamal, J. Mammen, B. Prabhakar and D. Shah,
     ``Throughput-Delay Trade-off in Wireless Networks''


GUEST SPEAKERS

  1. Dr. Gerhard Kramer, Bell Labs

             Title: Communication Models and Information Theory for
                       Relay Channels with Transmit and Receive Constraints
             Date: Friday, October 22, 2004
             Time: 11:00 a.m.
             Location: Room 2460, AVW Building
             Abstract
                        A relay network has a source terminal transmitting a
                 message to a destination terminal with the help of one or more relays.
                 Such a situation might occur in a multi-hop or sensor network where
                 there are several terminals that help each other transmit data. 
                 We develop simple communication models for such networks, review
                 existing information theory for the models, and develop several
                  multi-hopping strategies, where by multi-hopping we mean that the
                  relays successively decode the message before it arrives at the destination.
                  We show that the rates of these strategies are information-theoretically
                  optimal for certain wireless scenarios.
                   We extend the results to wider classes of problems, including relays that
                   cannot transmit and receive at the same time. For this last case, we show
                   that the best coding strategies use random, rather than predetermined,
                   slot structures.

                  
Relevant Publications:
               1. Capacity Theorems for Wireless Relay Channels
               2. Information–theoretic Multi–hopping for Relay Networks
               3. Models and Theory for Relay Channels with Receive Constraints
               4. Cooperative Strategies and Capacity Theorems for Relay Networks


    
2.  Dr. Piyush Gupta, Bell Labs

             TitleRandom-Access Scheduling with Service Differentiation in                                     
                       
Wireless Data Networks            
             Date
: Friday, November 5, 2004
             Time: 11:00 a.m.
             Location: Room 3120, CSIC
             Abstract
                   Recent years have seen tremendous growth in wireless local area
                 networking. An important issue in such networks is that of distributed
                 scheduling. Unlike in cellular networks, there is no central agent
                 that coordinates the medium access of all users in a cell. This leads
                 to significant throughput degradation due to multi-user contention.
                 Existing approaches, such as Slotted Aloha or IEEE 802.11, also fail
                 to provide differentiated service to users. We describe a class of
                 new distributed scheduling algorithms, Regulated Contention Medium
                 Access Control (RCMAC), which provides dynamic prioritized access to
                 users for service differentiation. Furthermore, by regulating
                 multi-user contention, RCMAC achieves higher throughput when traffic
                 is bursty, as is typically the case. We also discuss ongoing work to
                 extend RCMAC to multi-hop wireless networking scenarios, such as
                 ad hoc networks and sensor networks.

                 (Based on joint work with Yogesh Sankarasubramaniam (G.Tech.) and
                  Alexander Stolyar (Bell Labs).)


                  Relevant Publications:
               1. Random-Access Scheduling with Service Differentiation in
                   Wireless Networks
               2. The Capacity of Wireless Networks
               3. Critical Power for Asymptotic Connectivity in Wireless Networks

            
      3.  Dr. Vijay Subramanian, Motorola

             Title: Convergence and Optimality of Opportunistic Scheduling
                       Algorithms
             Date: Friday, November 19, 2004
             Time: 11:00 a.m.
             Location: Room 2460, AVW Building

             Abstract
                   With an abstraction of serving rate-adaptive sources on a
                 broadcast-type wireless channel as a utility maximization problem, it is
                 shown how one can design many intuitive online scheduling policies based
                 upon the feedback that one obtains at the scheduler. Using a stochastic
                 approximation argument it is then shown that the constructed algorithms
                 converge to optimal solutions of the utility maximization problem over
                 different sets which critically depend on the quality of the feedback
                  information.

                  We then apply the theory developed above to the downlink in a CDMA based
                  wireless network. In terms of operational variables the problem is to
                  select a subset of the users for transmission at each transmission
                  opportunity and for each of the users selected, to choose the modulation
                  and coding scheme, transmission power, and number of codes used. We
                  refer to this combination as the physical layer operating point (PLOP).
                  Each PLOP consumes different amounts of code and power resources.

                  Thus, the task is to pick the ``optimal'' PLOP taking into account both
                  system-wide and individual user resource constraints that can arise in a
                  practical system. Using an information theoretic model for the
                  achievable rate per code results in a tractable convex optimization
                  problem. By exploiting the structure of this problem, we give
                  algorithms for finding the optimal solution with geometric convergence.
                  We also use insights obtained from the optimal solution to construct
                  low complexity near optimal algorithms that are easily implementable.
                  Numerical results comparing these algorithms are also given.
  
                  Relevant Publications:
              1. Optimality of Certain Channel Aware Scheduling Policies
              2. Joint Scheduling and Resource Allocation in CDMA Systems
              3. Presentation Slides

       4.  Dr. Venu Veeravalli, NSF (University of Illinois)

             Title
:
             Date: Friday, December 10, 2004
             Time:
             Location: Room 2460, AVW Building


REFERENCES

There is no required textbook for the course. Material
for the lectures will be extracted from
books and technical articles in journals which are
listed below.

Important: The student is expected to be self-driven and
brimming with initiative. The field of wireless communication
networks is vast, but the lecture-time is short. The student is,
therefore, expected -- of her or his own volition -- to assimilate,
assimilate, assimilate ... from the material below.
The contents of the lectures, by necessity, will be neither
complete nor exhaustive.

A. Books

[1]. A. Goldsmith, Wireless Communications, Cambridge University Press
(to appear, 2005)
(http://wsl.stanford.edu/andrea/EE359Reader/).

[2]. K. Pahlavan and A.H. Levesque, Wireless Information Networks,
John Wiley & Sons, New York (NY) (1995).

[3]. K. Pahlavan and P. Krishnamurthy, Principles of Wireless Networks,
Prentice-Hall PTR (NJ) (2002).

[4]. T.S. Rappaport, Wireless Communications: Principles & Practice,
Prentice-Hall, Upper Saddle River (NJ) (1996).

[5]. C. Siva Ram Murthy and B.S. Manoj, Ad Hoc Wireless Networks:
Architectures and Protocols
, Prentice-Hall PTR (NJ) (2004).

[6]. R. Steele, Mobile Radio Communications,
IEEE Press, New York (NY) (1995).

[7]. G. L. Stüber, Principles of Mobile Communication,
Second Edition, Kluwer Academic, Boston (MA) (2001).

[8]. D. Tse and P. Viswanath, Fundamentals of Wireless Communications
(draft dated August 13, 2004)
(http://www.eecs.berkeley.edu/~dtse/main.pdf).

B. Journal articles, Conference proceedings, etc.

An overdose of information can be found in the following
  • journals
IEEE/ACM Transactions on Networking
IEEE Transactions on Communications
IEEE Journal on Selected Areas in Communications
IEEE Transactions on Information Theory
IEEE Transactions on Computers
IEEE Transactions on Vehicular Technology
IEEE Communications Magazine
IEEE Personal Communications Magazine
IEEE Wireless Communications
IEEE Network -- The Magazine of Computer Communications
Journal of the Association for Computing Machinery
Journal of High Speed Networks
ACM Journal on Wireless Networks
Computer Networks and ISDN
Proceedings of the IEEE

and
  • conference proceedings
Infocom
Globecom
International Conference on Communications (ICC)
Vehicular Technology Conference (VTC)
IEEE International Symposium on Information Theory (ISIT).

A recommendation:
You are encouraged to visit Andrea Goldsmith's
website at

http://www.stanford.edu/class/ee360/

for her Spring 2004 course at Stanford University
on "Advanced Topics in Wireless Communications."
It contains a well-organized and rich collection
of relevant reference material.