Building a service delivery system via SMS based on mobile subscriber location - 1

HANOI NATIONAL UNIVERSITY

UNIVERSITY OF TECHNOLOGY

PHAM THI HIEN

BUILDING A SYSTEM TO PROVIDE SERVICES VIA SMS

BASED ON MOBILE SUBSCRIBER LOCATION

Industry: Information Technology Major: Information Systems Code: 60 48 05

MASTER'S THESIS

SCIENCE GUIDE

DR. NGUYEN HAI CHAU

Hanoi – 2009

ACKNOWLEDGEMENTS

First of all, I would like to express my sincere thanks to Dr. Nguyen Hai Chau, Head of the Department of Information Systems, who has wholeheartedly guided me throughout my thesis.

I would like to thank the teachers at the Faculty of Information Technology, Graduate School, University of Technology - VNU Hanoi who taught me during my time at the school and created conditions to help me complete this thesis. Thank you to my friends and colleagues who have encouraged me throughout my time at the school.

Although there have been certain efforts, due to limited time and level, this thesis certainly has many shortcomings and limitations. We look forward to receiving comments from teachers and friends.

This master's thesis was conducted within the framework of the research project code QG.09.27, Vietnam National University, Hanoi.

Hanoi, December 12, 2009

Student

Pham Thi Hien

COMMITMENT

I hereby certify that the results obtained in this thesis are the product of my own research and study. In the entire content of this thesis, the things presented are either my own or compiled from many sources. All references have clear origins and are legally cited.

I accept full responsibility and accept all forms of discipline as prescribed for my commitment.

Hanoi, December 12, 2009

The pledger

Pham Thi Hien

INDEX

ABBREVIATIONS 6

LIST OF DRAWINGS 8

INTRODUCTION 10

CHAPTER 1 - GSM MOBILE INFORMATION SYSTEM 13

1.1. Introduction 13

1.1.1. GSM mobile communication system 13

1.1.2. Characteristics of GSM mobile communication system 13

1.2. Structure and function of components in GSM mobile communication system 15

1.2.1. System structure 15

1.2.2. Functions of components 16

1.3. SMS service in GSM mobile information system 22

1.3.1. Overview of SMS 22

1.3.2. Some network components involved in sending/receiving SMS 23

1.3.3. Basic services of SMS 24

CHAPTER 2 - SUBSCRIBER LOCATION TECHNIQUES THROUGH BTS STATIONS ... 25 2.1. Some location-based services 25

2.2. Subscriber positioning techniques in GSM mobile information network 26

2.2.1. Cell site Identification (Cell-ID) 29 positioning technique

2.2.2. Enhanced Observed Time Difference (EOTD) positioning technique 31

2.2.3. Assisted GPS (A-GPS) positioning technology 33

2.2.4. Combined method 35

2.3. Some location-based services for mobile phones in Vietnam 38

2.3.1. MobiFone SMS Locator Service 38

2.3.2. Google My Location (beta) 41

2.3.3. Shortest path finding service of DolSoft company 42

CHAPTER 3 - BUILDING A SYSTEM TO PROVIDE SMS SERVICES BASED ON MOBILE SUBSCRIBER LOCATION 45

3.1. Statement of problem 45

3.2. Survey of problem 45

3.3. System architecture and open source system support tools 46

3.3.1. System architecture 46

3.3.2. Kannel and SMS gateway 47

3.3.3. Selenium SMSC Simulator (SMPPSim) 50

3.3.4. Connect Kannel and SMPPSim to send messages 51

3.4. System analysis and design 53

3.5. Building the system 56

CONCLUSION 66

REFERENCES 68

ABBREVIATIONS

Acronym

Full Name - Description
AuC	Authentication Center – Authentication Center
BSC	Base Station Center - Base Station Controller
BSS	Base Station Subsystem - Base Station Subsystem
BTS	Base Transceiver Station – Base Radio Station
EIR	Equipment Identification Register - Equipment Identification Register
FDMA.	Frequency Division Multiple Access – Frequency Division Multiple Access
GGSN	Gateway GPRS Support Node – Gateway between GPRS and external networks
GMSC	Gateway Mobile Switching Center - Gateway Mobile Service Switching Center
GPRS	General Packet Radio Service – General Packet Radio Service
GSM	Global System for Mobile Communication – Global System for Mobile Communication
HLR	Home Location Register - Home Location Register
IMEI	International Mobile Equipment Identity – International Mobile Equipment Identity
ISDN	Integrated Service Digital Network - A digital network that combines services using common standard interfaces.
LBS	Location Based Services – Location Based Services
LMU	Location Measurement Units – Location Measurement Units
MMS	Multimedia Messaging Service – Multimedia Messaging Service
MOSM	Mobile Originated Short Message - Transfers messages from mobile stations to SMSC.
MS	Mobile Station – Mobile Station
MSC	Mobile service Switching Center - Mobile service switching center

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This is a simple priority queue scheduling technique. At the edges of the DS domain, EF packet traffic is prioritized according to the values ​​agreed upon by the SLA. The EF queue in the figure needs to output packets at a rate higher than the packet arrival rate λ. To provide an EF PHB over an end-to-end DS domain, bandwidth at the output ports of the core routers needs to be allocated in advance to ensure the requirement μ > λ. This can be done by a pre-configured provisioning process. In the figure, EF packets are placed in the priority queue (the upper queue). With such a length, the queue can operate with μ > λ. Since EF was primarily used for real-time services such as voice and video, and since real-time services use UDP instead of TCP, RED is generally not suitable for EF queues because applications using UDP will not respond to random packet drop and RED will strip unnecessary packets. 2.2.4.2 Assured Forwarding (AF) PHB PHB AF is defined by RFC 2597. The purpose of PHB AF is to deliver packets reliably and therefore delay and jitter are considered less important than packet loss. PHB AF is suitable for non-real-time services such as applications using TCP. PHB AF first defines four classes: AF1, AF2, AF3, AF4. For each of these AF classes, packets are then classified into three subclasses with three distinct priority levels. Table 2.8 shows the four AF classes and 12 AF subclasses and the DSCP values ​​for the 12 AF subclasses defined by RFC 2597. RFC 2597 also allows for more than three separate priority levels to be added for internal use. However, these separate priority levels will only have internal significance. PHB Class PHB Subclass Package type DSCP AF4 AF41 Short 100010 AF42 Medium 100100 AF43 High 100110 AF3 AF31 Short 011010 AF32 Medium 011100 AF33 High 011110 AF2 AF21 Short 010010 AF22 Medium 010100 AF23 High 010110 AF1 AF11 Short 001010 AF12 Medium 001100 AF13 High 001110 Table 2.8 AF DSCPs The AF PHB ensures that packets are forwarded with a high probability of delivery to the destination within the bounds of the rate agreed upon in an SLA. If AF traffic at an ingress port exceeds the pre-priority rate, which is considered non-compliant or “out of profile”, the excess packets will not be delivered to the destination with the same probability as the packets belonging to the defined traffic or “in profile” packets. When there is network congestion, the out of profile packets are dropped before the in profile packets are dropped. 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Figure 2.12 DiffServ Example Core functionality: When a DS-marked packet arrives at a Diffservcapable router, the packet is forwarded to the next router based on Per-hop behavior is associated with packet classes. Per-hop behavior affects router buffers and the bandwidth shared between competing classes. An important principle of the Differentiated Service architecture is that a router's per-hop behavior is based only on the packet's marking or the class to which it belongs. Therefore, if packets sent from H1 to H3 as shown in the figure receive the same marking as packets from H2 to H4, then the network routers treat the packets exactly the same, regardless of whether the packet originated from H1 or H2. For example, R3 does not distinguish between packets from h1 and H2 when forwarding packets to R4. Therefore, the Differentiated Service architecture avoids the need to maintain router state about separate source-destination pairs, which is important for network scalability. Chapter Conclusion Chapter 2 has presented and clarified two main models of deploying and installing quality of service in IP networks. While the traditional best-effort model has many disadvantages, later models such as IntServ and DiffServ have partly solved the problems that best-effort could not solve. IntServ follows the direction of ensuring quality of service for each separate flow, it is built similar to the circuit switching model with the use of the RSVP resource reservation protocol. IntSer is suitable for services that require fixed bandwidth that is not shared such as VoIP services, multicast TV services. However, IntSer has disadvantages such as using a lot of network resources, low scalability and lack of flexibility. DiffServ was born with the idea of ​​solving the disadvantages of the IntServ model. DiffServ follows the direction of ensuring quality based on the principle of hop-by-hop behavior based on the priority of marked packets. The policy for different types of traffic is decided by the administrator and can be changed according to reality, so it is very flexible. DiffServ makes better use of network resources, avoiding idle bandwidth and processing capacity on routers. In addition, the DifServ model can be deployed on many independent domains, so the ability to expand the network becomes easy. Chapter 3: METHODS TO ENSURE QoS FOR MULTIMEDIA COMMUNICATIONS In packet-switched networks, different packet flows often have to share the transmission medium all the way to the destination station. To ensure the fair and efficient allocation of bandwidth to flows, appropriate serving mechanisms are required at network nodes, especially at gateways or routers, where many different data flows often pass through. The scheduler is responsible for serving packets of the selected flow and deciding which packet will be served next. Here, a flow is understood as a set of packets belonging to the same priority class, or originating from the same source, or having the same source and destination addresses, etc. In normal state when there is no congestion, packets will be sent as soon as they are delivered. In case of congestion, if QoS assurance methods are not applied, prolonged congestion can cause packet drops, affecting service quality. In some cases, congestion is prolonged and widespread in the network, which can easily lead to the network being "frozen", or many packets being dropped, seriously affecting service quality. Therefore, in this chapter, in sections 3.2 and 3.3, we introduce some typical network traffic load monitoring techniques to predict and prevent congestion before it occurs through the measure of dropping (removing) packets early when there are signs of impending congestion. 3.1. DropTail method DropTail is a simple, traditional queue management method based on FIFO mechanism. 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After those monopolized connections are temporarily suspended, Once the queue is cleared, it takes a considerable amount of time for TCP connections to return to their original speed. − Full Queue phenomenon: Data transmitted on the Internet often has an explosion, packets arriving at the router are often in clusters rather than in turn. Therefore, the operating mechanism of DropTail makes the queue easily full for a long period of time, leading to the average delay time of large packets. To avoid this phenomenon, with DropTail, the only way is to increase the router's buffer, this method is very expensive and ineffective. − No QoS guarantee: With the DropTail mechanism, there is no way to prioritize important packets to be transmitted through the router earlier when all are in the queue. Meanwhile, with multimedia communication, ensuring connection and stable speed is extremely important and the DropTail algorithm cannot satisfy. 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Due to its outstanding advantages compared to previous queue management algorithms, RED has been widely installed and deployed on the Internet. The most fundamental point of their work is that the most effective place to detect congestion and react to it is at the gateway or router. Source entities (senders) can also do this by estimating end-to-end delay, throughput variability, or the rate of packet retransmissions due to drop. However, the sender and receiver view of a particular connection cannot tell which gateways on the network are congested, and cannot distinguish between propagation delay and queuing delay. Only the gateway has a true view of the state of the queue, the link share of the connections passing through it at any given time, and the quality of service requirements of the traffic flows. The RED gateway monitors the average queue length, which detects early signs of impending congestion (average queue length exceeding a predetermined threshold) and reacts appropriately in one of two ways: − Drop incoming packets with a certain probability, to indirectly inform the source of congestion, the source needs to reduce the transmission rate to keep the queue from filling up, maintaining the ability to absorb incoming traffic spikes. − Mark “congestion” with a certain probability in the ECN field in the header of TCP packets to notify the source (the receiving entity will copy this bit into the acknowledgement packet). Figure 3. 1 RED algorithm The main goal of RED is to avoid congestion by keeping the average queue size within a sufficiently small and stable region, which also means keeping the queuing delay sufficiently small and stable. Achieving this goal also helps: avoid global synchronization, not resist bursty traffic flows (i.e. flows with low average throughput but high volatility), and maintain an upper bound on the average queue size even in the absence of cooperation from transport layer protocols. To achieve the above goals, RED gateways must do the following: − The first is to detect congestion early and react appropriately to keep the average queue size small enough to keep the network operating in the low latency, high throughput region, while still allowing the queue size to fluctuate within a certain range to absorb short-term fluctuations. As discussed above, the gateway is the most appropriate place to detect congestion and is also the most appropriate place to decide which specific connection to report congestion to. − The second thing is to notify the source of congestion. This is done by marking and notifying the source to reduce traffic. Normally the RED gateway will randomly drop packets. However, if congestion If congestion is detected before the queue is full, it should be combined with packet marking to signal congestion. The RED gateway has two options: drop or mark; where marking is done by marking the ECN field of the packet with a certain probability, to signal the source to reduce the traffic entering the network. − An important goal that RED gateways need to achieve is to avoid global synchronization and not to resist traffic flows that have a sudden characteristic. Global synchronization occurs when all connections simultaneously reduce their transmission window size, leading to a severe drop in throughput at the same time. On the other hand, Drop Tail or Random Drop strategies are very sensitive to sudden flows; that is, the gateway queue will often overflow when packets from these flows arrive. To avoid these two phenomena, gateways can use special algorithms to detect congestion and decide which connections will be notified of congestion at the gateway. The RED gateway randomly selects incoming packets to mark; with this method, the probability of marking a packet from a particular connection is proportional to the connection's shared bandwidth at the gateway. − Another goal is to control the average queue size even without cooperation from the source entities. This can be done by dropping packets when the average size exceeds an upper threshold (instead of marking it). This approach is necessary in cases where most connections have transmission times that are less than the round-trip time, or where the source entities are not able to reduce traffic in response to marking or dropping packets (such as UDP flows). 3.2.2 Algorithm This section describes the algorithm for RED gateways. RED gateways calculate the average queue size using a low-pass filter. This average queue size is compared with two thresholds: minth and maxth. When the average queue size is less than the lower threshold, no incoming packets are marked or dropped; when the average queue size is greater than the upper threshold, all incoming packets are dropped. When the average queue size is between minth and maxth, each incoming packet is marked or dropped with a probability pa, where pa is a function of the average queue size avg; the probability of marking or dropping a packet for a particular connection is proportional to the bandwidth share of that connection at the gateway. The general algorithm for a RED gateway is described as follows: [5] For each packet arrival Caculate the average queue size avg If minth ≤ avg < maxth div.maincontent .s1 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 15pt; } div.maincontent .s2 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 15pt; } div.maincontent .p { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; margin:0pt; } div.maincontent p { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; margin:0pt; } div.maincontent .s3 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s4 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s5 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s6 { color: black; font-family:"Times New Roman", serif; font-style: italic; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s7 { color: black; font-family:Wingdings; font-style: normal; font-weight: normal; text-decoration: none; font-size: 14pt; } div.maincontent .s8 { color: black; font-family:Arial, sans-serif; font-style: italic; font-weight: bold; text-decoration: none; font-size: 15pt; } div.maincontent .s9 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: bold; text-decoration: none; font-size: 14pt; } div.maincontent .s10 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 9pt; vertical-align: 6pt; } div.maincontent .s11 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 13pt; } div.maincontent .s12 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-decoration: none; font-size: 10pt; } div.maincontent .s13 { color: black; font-family:"Times New Roman", serif; font-style: normal; font-weight: normal; text-d
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MTSM

MTSM (Mobile Terminated Short Message – Transfers messages from SMSC to mobile stations or other devices.
NMC	Network Management Center - Network Management Center
NSS	Network switching SubSystem - Switching Subsystem
OMC	Operation & Maintenance Center - Operation & Maintenance Center
OMS	Operation and Maintenance SubSystem - Operation and Maintenance Subsystem
PCU	Packet Control Unit - packet control unit
PIN	Personal Identity Number – Personal Identity Number
PLMN	Public Land Mobile Network – Public Land Mobile Network
PSTN	Public Switched Telephone Network - Public Switched Telephone Network
RSS	Radio SubSystem - Radio Subsystem
SGSN	Serving GPRS Support Node - an element in the GPRS network that connects the access network and the GGSN gateway
SIM	Subscriber Identity Module – Subscriber Identity Module
SMPP	Short Message Peer-to-peer Protocol - Short Message Peer-to-peer Protocol
SMS	Short Message Services – Short Message Services
SMSC	Short Message Services Center – Short Message Services Center
SS7	Signaling System #7 – Signaling System #7
TDMA	Time Division Multiple Access - Time Division Multiple Access
VLR	Visitor Location Register - Visitor Location Register

LIST OF DRAWINGS

Figure 1: GSM mobile information system model 13

Figure 2: SMS Gateway with forwarding function 21

Figure 3: SMS Gateway with the function of connecting gateway 21

Figure 4: BTS broadcasts in 3 directions 25

Figure 5: Cell-ID 27 positioning technique

Figure 6: Positioning using Cell-ID and TA 29

Figure 7: Positioning based on: E-OTD hyperbolic 30

Figure 8: A-GPS Architecture 32

Figure 9: MobiFone SMS Locator service 36

Figure 10: System architecture 45

Figure 11: Interface for sending messages from SMPPSim 49

Figure 12: Part of Google Static Map 57

Figure 13: Map of an area in Hanoi obtained from Google Static Map 59

Figure 14: Map of an area in Ho Chi Minh City obtained from Google Static Map 60

Figure 15: An example of a map returning results to the user 62

Figure 16: An example of a map returning results to the user 63

LIST OF TABLES

Table 1: Cell-ID 28 positioning technique evaluation table

Table 2: EOTD 31 positioning technique evaluation table

Table 3: A-GPS 33 positioning technique evaluation table

Table 4: Technical evaluation table of Cell-ID positioning combined with A-GPS 34

Table 5: Summary of characteristics of positioning techniques 35

Table 6: List of MobiFone services 37

Table 7: List of bank codes that can use MobiFone's SMS Locator service 38

Table 8: List of some BTS of MobiFone 52

Table 9: BTS 53 attributes table

Table 10: Table of attributes of service points 53

Table 11: Table of URL attributes 54