A Wireless Design Tool

學生 :陳信旭學號 :s937471

Outline

‧ INTRODUCTION

‧ DESIGN CHALLENGES

‧ DESIGN PROCEDURE WITHOUT ROLLABOUT

‧ ROLLABOUT DESIGN TOOL OVERVIEW

‧ CONCLUSION

INTRODUCTION

‧ Reliability

‧ Performance

‧ Deployment

‧ Security

‧ Mobility

‧ Network management

INTRODUCTION(Cont.)

Reliability and performance depend on proper deployment

Site survey: the characteristics of the radio propagation environment.

Design: AP locations : Avoid coverage gaps.

Radio frequencies : Minimizes co-channel coverage overlap.

INTRODUCTION(Cont.)

1. Collects data from APs

2. Automatically creates a coverage map

3. Optimal AP placement and determine the best frequency assignments

4. Drag-and-drop capability : Relocate an AP on the computer screen;

it then gives an estimate of the resulting coverage pattern

DESIGN CHALLENGES

Typical transmission ranges go up to 300 m in an open environment, but this range may be reduced to 20–60 m through walls and other partitions in some office environments.

‧ impediment .

‧ Network performance .

‧ radio interference :multiple frequencies can be very helpful in minimizing cochannel overlap .

DESIGN PROCEDURE WITHOUT ROLLABOUT

• Initial selection of AP locations

• Test and redesign (i.e., adjusting AP locations based on signal

strength measurements)

• Creation of a coverage map

• Assignment of frequencies to APs

• Audit (i.e., documenting the final AP locations, coverage areas, and

frequencies selected)

ROLLABOUT DESIGN TOOL OVERVIEW

Hardware includes three major components:

1. A specially built cart, 2. A set of position location electronics :

The position location electronics equipment interfaces the two shaft encoders to the PC and provides the positions of the two encoders to the computeri.e., magnetic compass and GPS.

3. Notebook PC ‧ Minimum 32 Mbytes RAM ‧Windows 95 or higher operating system ‧ Serial port running at 9600 b/s

ROLLABOUT DESIGN TOOL OVERVIEW(Cont.)

Figure 1. Rollabout: cart, position location electronics, and notebook PC.

ROLLABOUT DESIGN TOOL OVERVIEW(Cont.)

PROCESSrolls the cart produces a coverage map determines the optimal set of frequency assignmentsDrag-and-drop

DISPLAY:The paused state(RED), data from the shaft encoders is ignored and no

position data is recorded.The live state(GREEN), data from the shaft encoders is recorded, and

position information is updated on the screen.

Rollabout uses a dead reckoning approach to position location, measuring all positions with respect to an initial position and an initial direction.

Signal strength and noise information may be displayed. ‧ Good: green ‧ Adequate: yellow ‧ Poor: red ‧ No signal: black

ROLLABOUT DESIGN TOOL OVERVIEW(Cont.)

Figure 2. Rollabout signal measurement screen.

Figure 3. Single Access Point Display Tool with popup window

ROLLABOUT DESIGN TOOL OVERVIEW(Cont.)

‧ shows signal strengths along the entire path traversed ‧ zoom in/zoom out ‧ allows one to see the coverage of multiple APs at the same

time (Fig. 4).

‧ FREQUENCY ASSIGNMENTThe Frequency assignment Tool can be used to create the

assignment of frequencies to APs that minimizes co- channel coverage overlap among APs.

algorithm:exponential:Optimal.

only be used for small configurations of 10 APs or less. greedy:Not optimal.

It requires far less computation and should be used for configurations in excess of 10 APs.

ROLLABOUT DESIGN TOOL OVERVIEW(Cont.)

Figure 4. Multiple Access Point Display Tool with popup window.

Figure 5. Rollabout Frequency Assignment Tool

ROLLABOUT DESIGN TOOL OVERVIEW(Cont.)

COVERAGE AREA PREDICTION ‧ To predict AP coverage areas.

‧ Insert, move, or delete APs to determine optimal

coverage using the smallest number of APs.

CONCLUSION

There is a strong need for tools that will produce a good WLAN design and also speed the design process.

Performance

Faster