Presenting an improved transport layer protocol for wireless surveillance systems

Dissertation

For Master Degree

Information Technology Engineering - Computer Networks Major

Abstract

Wireless surveillance networks are an important branch of wireless multimedia sensor networks with some unique features. The quality of service in wireless surveillance networks is closely related to the packet loss rate. Occurrence of congestion is one of the main and most important reasons for packet loss in the network. Packet loss in wireless surveillance networks, depending on the type of lost packet, can have significant effects in reducing the quality of the received video. One of the important factors that can play a significant role in improving the quality of video transmission is the queuing policy used in the router and including multimedia content and packet priority. In recent years, extensive studies have been conducted on obtaining transport layer protocols for effective congestion control in wireless multimedia sensor networks. However, most of these algorithms work regardless of multimedia content. In this thesis, the congestion control mechanism for wireless sensor networks is first presented, which is done by using feedback from intermediate routers to control the sending rate by sensors as effectively as possible. Then the priority queuing policy is used to improve the quality of the received video. Finally, the possibility of retransmission for packets with higher priority has been checked and the improvement rate has been obtained for different network states. The simulation was done using the ns-2 simulator and the simulation results indicate that the proposed mechanisms have better performance in the received video quality compared to other existing mechanisms.

Key words: wireless surveillance networks, multimedia sensor networks, congestion control, transmission layer, quality of service.

1 Chapter 1:

Introduction

Research questions

In order to review and improve the protocols of the transmission layer of wireless surveillance networks, one must first gain a deep understanding of the conditions of the problem and the relevant challenges, then using this information, appropriate solutions were provided. If some of the needs of the problem are not satisfied by the existing solutions, a new solution should be provided. Therefore, the questions that are raised and enlighten the path of this research are:

What kind of traffic is there in surveillance networks and what are their characteristics?

What components are surveillance networks made of and what facilities do they provide?

What are the requirements of wireless surveillance networks?

What is multimedia and real-time traffic? Do they have an effect on the design of transport layer protocols?

How do the characteristics of wireless surveillance networks (including: high data rate and high packet loss rate) affect the design of transport layer protocols?

For wireless surveillance networks, stateless protocols [1] or stateful protocols [2] are more suitable?

How can the transport layer be used in surveillance networks? Optimized wireless?

1-1 Thesis structure

The overall structure of the thesis is as follows:

In the second chapter, a background of the main topics including explanations of wireless sensor networks and wireless multimedia sensor networks and discussions in multimedia are presented, and then it describes the classification of wireless multimedia sensor networks and an overview of wireless monitoring systems. which is an important group of wireless multimedia sensor networks with unique features.

In the third chapter, we will describe the environmental conditions and characteristics of wireless surveillance networks, examine the upcoming challenges and introduce the important parameters required for evaluation.

The fourth chapter includes the introduction, evaluation and comparison of proposed protocols for networks with features such as wireless communication line, high packet loss rate. In the network, there are high data rates, multimedia traffic, real-time traffic, service quality requirements [3], etc.

In the fifth chapter, we present our work and state the results and improvements and compare it with some of the proposed protocols.

And finally, in the sixth chapter, we draw a conclusion from this research and mention some examples of work that can be done in the future.

1 Chapter 2:

Background

Wireless surveillance networks are an important category of wireless multimedia sensor networks, the dominant traffic of which is multimedia (videos, images and sounds obtained from sensors). In order to better understand these networks, it is first necessary to have a preliminary understanding of multimedia and then to study wireless multimedia sensor networks and the generation before it, i.e. wireless sensor networks. 1-1 Multimedia What is multimedia? People who use the word multimedia are divided into different categories with different views. they become For example, the seller of a multimedia computer as a computer that includes a sound system, DVD optical drive, etc. knows An entertainment vendor may consider multimedia as an interactive cable television system with access to hundreds of digital channels over the Internet or network. In computer science, the concept of multimedia is a set of modules such as text[1], images[2], graphics[3], animation[4], video[5] and sound[6] that can be interactive. These concepts that consider different aspects of video are:

Types of video signals

Analog video

Digital video

Since video is made from many different sources, we will start with the signal itself. Analog video is represented as a continuous signal. Digital video is also represented as a series of digital images. At the end of this section, we will describe digital video compression methods. 1-1-1 Types of video signals Video signals can be classified into 3 separate categories: 1) Component video [7] 2) Composite video [8] and 3) S-video [9].

Component video

When from 3 separate video signals are used for red, green and blue planes, known as component video. These types of wires include 3 wires (connectors) that are used to connect the camera or other devices to the TV or monitor.

Composite video

In composite video, the color ("chrominance") and intensity ("luminance") of the signals are mounted in a carrier wave. Chrominance is the combination of two colors (I and Q or U and V). This system is used in the general TV segment because it is also compatible with black-and-white TVs.

S-Video

S-Video uses two wires: one for luminance and one for the combined chrominance signal.

1-1-2 Analog Video

An analog signal f(t) samples a time-varying image. does In the progressive scanning method [10], an image (frame) is scanned completely from the beginning. In another method called scanning one in between [11], image lines are scanned in one in between (even and odd lines). The main broadcast television standards are:

NTSC

It is a standard widely used in North America and Japan. In this standard, the 4:3 ratio and the one-in-one scanning method are used. Also, in this standard, 30 frames per second and 525 lines are scanned per frame.

PAL

is a television standard invented by German scientists. This standard uses scanning at 625 lines per frame and 25 frames per second with a 4:3 aspect ratio and interlaced scanning. This important standard is widely used in Western Europe, China, India and many other parts of the world.

SECAM

Invented by the French, this standard is the third major standard in public television broadcasting. SECAM also uses 625 line-per-frame scans, 25 frames per second, with a 4:3 aspect ratio and scanning once in between. SECAM and PAL are similar except that they use a different color coding scheme. In Table 2-1, the standards of public television broadcasting are briefly compared.