1. Introduction to Wireless Networking
ECE/CSC 575 – Section 1
Introduction to Wireless Networking
Lecture 11 Dr. Xinbing Wang

2. Current Wireless Systems: Cellular Systems--UMTS
Fundamentals of cellular communications
System capacity
frequency reuse
Cell splitting
Admission control
handoff
Universal mobile telecommunication system (UMTS)
Network architecture
Functional units
Quality of service
Mobility management
In our daily lives, wireless communication technology is used everywhere, from VCR remote control, to satellite weather forecast. The common characteristics of wireless communication systems is that there is no physical (visible) lines between two communication parties.
Therefore, a wireless system is able to support user roaming. For example, we do not have to use a remote control in a particular position to.., we can use our cellular phones almost everywhere.
However, there are many impairments to a wireless channel, causing a lot of limitations to wireless communications system such as geographical.. (signal fading, additional noise, cochannel interference. Wireless systems also suffers from limit usable spectral width, so that the transmission rate is relatively low.
Specifically, wireless cellular systems based on radio propagation has been evolving from narrow band (1G, late 170s) to wide-band(3G).
With their geographical coverage limitation, wireless systems need a backbone network to extend their geographical coverage to enable global communications.
The interoworking of a wireless network as the front-end and the Internet as the backbone has received much attention in recent years.
So we will first take a look at the network architecture of current wireless systems,…, Then we will talk about the evolution from 2G to 3G systems.
Dr. Xinbing Wang

3. Quality of Services Classes
The UMTS allows the UEs to negotiate the QoS parameters for a radio bearer (RB).
Negotiation
The procedure is always initiated by the application in the UE.
It sends a request defining the resources it needs
The network checks whether it can provide the requested resources.
It can either grant the requested resources, offer a small amount of resources, or reject the request.
The UE can either accept or reject the modified offer.
It is also possible to renegotiate these parameters if the application requirements change or resource status change.
Dr. Xinbing Wang

4. Control of Requested QoS
The UTRAN air interface is very flexible, which allows for the dynamic allocation of system resources.
In the connected mode, the UE may be required to perform traffic volume measurements in its MAC layer. If the UE suspects that the present configuration is not the optimal one, it sends a measurement report to the network.
The network can trigger a channel-reconfiguration procedure.
Increased data
Decreased data
Dr. Xinbing Wang

5. UMTS Services (Originally)
Data transmission service profile
Circuit switched
16 kbit/s
Voice
SMS successor,
Packet switched
14.4 kbit/s
Simple Messaging
Switched Data
asymmetrical, MM, downloads
384 kbit/s
Medium MM
Low coverage, max. 6 km/h
2 Mbit/s
High MM
Bidirectional, video telephone
128 kbit/s
High Interactive MM
Transport mode
Bandwidth
Service Profile
Dr. Xinbing Wang

6. Current Wireless Systems: Cellular Systems--UMTS
Fundamentals of cellular communications
System capacity
frequency reuse
Cell splitting
Admission control
handoff
Universal mobile telecommunication system (UMTS)
Network architecture
Functional units
Quality of service
Mobility management
In our daily lives, wireless communication technology is used everywhere, from VCR remote control, to satellite weather forecast. The common characteristics of wireless communication systems is that there is no physical (visible) lines between two communication parties.
Therefore, a wireless system is able to support user roaming. For example, we do not have to use a remote control in a particular position to.., we can use our cellular phones almost everywhere.
However, there are many impairments to a wireless channel, causing a lot of limitations to wireless communications system such as geographical.. (signal fading, additional noise, cochannel interference. Wireless systems also suffers from limit usable spectral width, so that the transmission rate is relatively low.
Specifically, wireless cellular systems based on radio propagation has been evolving from narrow band (1G, late 170s) to wide-band(3G).
With their geographical coverage limitation, wireless systems need a backbone network to extend their geographical coverage to enable global communications.
The interoworking of a wireless network as the front-end and the Internet as the backbone has received much attention in recent years.
So we will first take a look at the network architecture of current wireless systems,…, Then we will talk about the evolution from 2G to 3G systems.
Dr. Xinbing Wang

7. Mobility Management Why mobility management?
To keep ongoing connections when users move in/out cells
To update mobile users locations in the home network for service delivery
What is mobility management?
Location management: to “locate” mobile users within a location area and to “update” home location register (HLR).
Handoff management: to “handoff” connections from one base station (BS) to another.
Dr. Xinbing Wang

8. Location Registration
Location registration: Mobile users register with a new MSC when they move out of a region controlled by an old MSC.
The mobile users register with a local/regional register, namely, visitor location register (VLR) in the visiting network.
The mobile users then update their locations in terms of location area (LA) in the home location register (HLR)
We assume one MSC is related to one or more LAs. And one MSC is collocated with one VLR.
Dr. Xinbing Wang

9. Call/Service Delivery
We assume that all calls will be delivered to the MT’ home network first, according to its permanent address (ID).
Call delivery is the process that the home network delivers calls to the MTs’ current locations based on the update location information stored in the VLR.
Dr. Xinbing Wang

10. Two-Tier Architecture
The first tier is centered on HLR and SS7.
The second tier is featured by VLRs and MSCs.
HLR
SS7
Home Location
Register (HLR)
Mobile Switching
Center (MSC)
Visitor Location
Register (VLR)
MSC
VLR
VLR
MSC
Cell
Location area
(LA)
Dr. Xinbing Wang

11. Overview of the Course--Brief review before Quiz 1
Part 1: Wireless communication systems (Chapter 1)
Flexibility to support roaming
Limitations: Geographical coverage, transmission rate, and transmission errors
Part 2: Wireless communication technology
Radio propagation (Chapter 5)
Spread spectrum (Chapter 7 -- Self reading (ECE 791W))
Coding and error control (Chapter 8 -- Self reading (ECE/CSC 570))
Part 3: Current wireless systems
Cellular network architecture: UMTS (Chapter 10)
Mobile IP (Chapter 12)
Wireless LAN (Chapters 11/13/14)
Part 4: Other wireless networks
Ad hoc networks (Reading materials)
Wireless PAN (Chapter 15)
Satellite systems (Chapter 9)
Sensor networks (Reading materials)
In our daily lives, wireless communication technology is used everywhere, from VCR remote control, to satellite weather forecast. The common characteristics of wireless communication systems is that there is no physical (visible) lines between two communication parties.
Therefore, a wireless system is able to support user roaming. For example, we do not have to use a remote control in a particular position to.., we can use our cellular phones almost everywhere.
However, there are many impairments to a wireless channel, causing a lot of limitations to wireless communications system such as geographical.. (signal fading, additional noise, cochannel interference. Wireless systems also suffers from limit usable spectral width, so that the transmission rate is relatively low.
Specifically, wireless cellular systems based on radio propagation has been evolving from narrow band (1G, late 170s) to wide-band(3G).
With their geographical coverage limitation, wireless systems need a backbone network to extend their geographical coverage to enable global communications.
The interoworking of a wireless network as the front-end and the Internet as the backbone has received much attention in recent years.
So we will first take a look at the network architecture of current wireless systems,…, Then we will talk about the evolution from 2G to 3G systems.
Dr. Xinbing Wang

12. Part 1-- Introduction Wireless communication systems
Flexibility to support roaming
Limitations: Geographical coverage, transmission rate, and transmission errors
Architectures of wireless networks
Cellular network architecture
Wireless LAN/PAN
Satellite systems
Ad hoc networks
Sensor networks
Background
FDMA/TDMA/CDMA
Connection setup
Dr. Xinbing Wang

13. Part 2: Radio Propagation
Wired and wireless medium
Radio propagation mechanism
Antenna and antenna gain
Path-loss modeling
Free Space model
Two-Ray model
Shadow fading
Different environments
Effect of Multipath and Doppler
Multipath fading
Doppler spectrum
Dr. Xinbing Wang

14. Part 3: Current Wireless Systems
Cellular network architecture: UMTS (Chapter 10)
Fundamentals of cellular communications
System capacity
frequency reuse
Cell splitting
Admission control
handoff
Universal mobile telecommunication system (UMTS)
Network architecture
Functional units
Quality of service
Mobility management
Mobile IP (Chapter 12)
Wireless LAN (Chapters 11/13/14)
In our daily lives, wireless communication technology is used everywhere, from VCR remote control, to satellite weather forecast. The common characteristics of wireless communication systems is that there is no physical (visible) lines between two communication parties.
Therefore, a wireless system is able to support user roaming. For example, we do not have to use a remote control in a particular position to.., we can use our cellular phones almost everywhere.
However, there are many impairments to a wireless channel, causing a lot of limitations to wireless communications system such as geographical.. (signal fading, additional noise, cochannel interference. Wireless systems also suffers from limit usable spectral width, so that the transmission rate is relatively low.
Specifically, wireless cellular systems based on radio propagation has been evolving from narrow band (1G, late 170s) to wide-band(3G).
With their geographical coverage limitation, wireless systems need a backbone network to extend their geographical coverage to enable global communications.
The interoworking of a wireless network as the front-end and the Internet as the backbone has received much attention in recent years.
So we will first take a look at the network architecture of current wireless systems,…, Then we will talk about the evolution from 2G to 3G systems.
Dr. Xinbing Wang

15. Overview of Mobile IP (Ch. 12)
Is Mobile IP an official standard?
The Internet allocates a fixed address to each and every mobile user. The current approach to forwarding messages from the mobile’s fixed address to it in its new location is Mobile IP.
Mobile IP was approved by the Internet Engineering Steering Group (IESG) in June 1996 and published as a Proposed Standard in November 1996.
Mobile IP was produced by the IP Routing form Wireless/Mobile Hosts (mobileip) working group of the Internet Engineering Task Force (IETF), which was formed in June 1992.
Request for Comments (RFC) 2002 defines the Mobile IP protocol itself.
Dr. Xinbing Wang

16. Why Mobile IP?
In IP networks, routing decisions are made based upon the network-prefix portion of the IP Destination Address.
This implies that all nodes with interfaces on a given link must have identical network-prefix portions of their IP addresses on those interfaces.
What is mobility? It is the ability for a node to change its point-of-attachment (POA) from one link to another while maintaining all existing communications and using the same IP address at its new link.
Mobile Node? It is defined as a node which is capable of mobility. It can change its POA to the Internet.
Mobile node (MN), mobile host (MH), mobile terminal (MT), and mobile station (MS) will be used interchangeably in this context.
Dr. Xinbing Wang

17. Why Mobile IP (2)
However, if a node changes from one link to another, then the network-prefix of its IP address would no longer equal the network-prefix assigned to its current link.
As a result, network-prefix routing would fail to deliver packets to the node’s current location!!
Thus, Mobile IP provides a mechanism for routing IP packets to mobile nodes which may be connected to any link while using their permanent IP address.
Mobile IP is a network-layer solution to node mobility in the Internet.
In fact, Mobile IP can be considered to be a routing protocol which, sets up the routing tables in appropriate nodes, such that IP packets can be sent to mobile nodes not connected to their home link.
Dr. Xinbing Wang

18. Requirements for Mobile IP
A mobile node must be able to communicate with other nodes after changing its link-layer point-of-attachment (POA).
Network-prefix-based routing algorithms won’t work
A mobile node must be able to communicate using only its home (permanent) IP address, regardless of its current POA.
Rules out any solution which calls for changing IP-addr
Network services are based on IP-addr such as licenses
A mobile node must be able to communicate with other computers that do not implement the Mobile IP mobility functions.
A mobile node must not be exposed to any new security threats over and above those to which any fixed node on the Internet is exposed.
Dr. Xinbing Wang

19. Design Goals for Mobile IP
Routing protocols, including Mobile IP, require the transmission of routing updates between the various nodes in the network. Therefore, one of the goals was to make the size and the frequency of these updates as small as possible.
For the purpose of memory and processing-constrained devices, to make it as simple as possible to implement mobile node software.
Because of the address limit, to avoid solutions which requires mobile nodes to use multiple addresses. (Solved by IPv6!)
Dr. Xinbing Wang

20. Assumptions in Mobile IP
Assume unicast packets--those destined to a single recipient—are routed without regard to their IP Source address.
That means, Mobile IP assumes that all unicast packets are routed based on Dest-addr, typically only the network-prefix portion of that address.
Assume that the Internet exists ‘always’ and that is capable of delivering packets between any pair of nodes in the network.
Dr. Xinbing Wang

21. Terminology
Home Address: an IP address that is assigned to an MN. It remains unchanged regardless of the MN’s current location.
Home Link: The link on which an MN’s home subnet prefix is defined. Standard IP routing mechanisms will deliver packets destined for an MN’s home address to its home link.
Home Agent: A router with an interface on the MN’s home network link, which the MN keeps informing of its care-of-address, as the MN moves.
Care-of-address: an IP address associated with an MN while visiting a foreign link (other than home link).
Correspondent node: a peer host with which a mobile node communicates.
Foreign Agent: a router with which an interface on an MN’s visiting network. Assists the MN in informing its HA of a CoA.
Dr. Xinbing Wang

22. How Does Mobile IP Work? Each MN has two IP addresses:
A fixed home address for identification, and
A care-of-address (CoA) for routing. The CoA can be created by “stateless address auto-configuration (RFC 2462)” and “stateful address autoconfiguration, e.g., DHCP).
Mobile IP uses an agent concept.
Home agent (HA) intercepts packets on the home link destined to the MN’s home address, encapsulates them, and tunnels them to the MN’s registered CoA.
Foreign agent (FA) is a router with which an MN establishes an association when it moves away from home. Therefore, the MN updates its locations with the HA through an FA.
Dr. Xinbing Wang

23. Mobile IP Operation
Home subnet prefix: the IP subnet prefix corresponding to an MN’s home address.
Foreign subnet prefix: the IP subnet prefix other than the MN’s home subnet prefix.
address B
Subnet prefix B
Internet Backbone
address B
& address C
Subnet prefix C
A node moves from a link with the prefix B to a link eith the prefix C. On link C the node gets an additional address which has the prefix of this link.
Dr. Xinbing Wang

24. Mobile IP Operation (2) HA Agent advertisement FA FA Home network/
Subnet
Correspondent
Node (CN) HA
Internet Backbone
Agent advertisement FA FA
Foreign Network/
Subnet 2
Foreign Network/
Subnet 1
Dr. Xinbing Wang