Overview of Mobile Communication Systems

Overview of Mobile Communication Systems

13年2月19⽇日星期⼆二

Contents• PSTN & PLMN

• Basic Mobile Communication Systems System Architecture

• Cellular Communication

• Cellular Network Standards

• Generations of Mobile Communication Systems

• Mobile Communication Systems


PSTN & PLMN

• 公眾電話交換網路(Public Switched Telephone Network，PSTN)

• 陸地行動電話網路(Public Land Mobile Network，PLMN)


PSTN• 1876年由貝爾發明的電話開始建立

• 用於全球語音通信的電路交換網路(circuit-switched telephone)

• 主要由交換系統和傳輸系統兩大部分組成

• 交換系統的主要設備

• 電話交換機

• 傳輸系統的主要設備

• 傳輸設備(如SDH-Synchronous Digital Hierarchy)

• 線纜(如銅線，光纖)


• 電話撥接

• 播出電話→經由電話線→連到電信公司的交換機(switch)進行轉接→轉到對方的有線電話

• 線路

• subscriber loop

• 從電話連到最近交換機(稱為central office或end office)的線路

• trunk

• 電信公司內部交換機間的連線


PLMN• PLMN is a network that is established and operated by

an administration or by a Recognized Operating Agency (ROA) for the specific purpose of providing land mobile telecommunications services to the public

• Access to PLMN services is achieved by means of an air interface involving radio communications between mobile phones or other wireless enabled user equipment and land based radio transmitters or radio base stations

• PLMNs interconnect with other PLMNs and PSTN for telephone communications or with internet service providers for data and internet access


PLMN Service Area of the Same Operator (GSM)


Basic Mobile Communication Systems System Architecture



Basic Mobile Communication Systems System Architecture

• 無線電網路(Radio Network)

• 有線傳輸網路(Wireline Transport Network)


Radio Network• Mobile Station (MS)

• PHS, GSM/GPRS, WCDMA, WiMax, LTE

• 基地台(Base Station，BS)

• BS所發射無線電波的涵蓋範圍(coverage)稱為細胞(cell)

• 某些系統，如GSM和PACS，其基地台系統是由控制台(controller)和無線電發射與接收(transceiver)設備組成


• 控制台

• 與交換機相接的部份

• GSM的控制台稱為基站控制台(Base Station Controller，BSC)

• PACS的控制台稱為無線電基地台控制單元(Radio Port Control Unit，RPCU)

• 傳輸專線

• 基地台與骨幹網路間以有線(wireline)傳輸專線或微波(microwave)專線相連



Antenna

Base Station


Wireline Transport Network• 行動交換中心

(Mobile Switching Center，MSC)

• BS連線到MSC

• MSC與PSTN銜接，提供行動用戶與PSTN用戶間的通訊服務

• 行動資料庫(Mobility Database)

• 與MSC溝通來追蹤MS的位置


蜂巢式無線通訊(Cellular Communication)

• 傳統式無線電話

• 每通無線電話會佔用整個頻率

• 由高功率的收發器負責訊號的傳送與接收

• 在有效半徑約80公里(約2萬平方公里)的面積中，僅容許25個頻道


• 蜂巢式無線通訊(Cellular Communication)

• 多個低功率(功率低於100W)的發射機取代原本一個高功率的發射機

• 以正六邊形的蜂巢單元(或細胞)(cellular unit or cell)組成無線小區，無線小區相鄰接，構成整個面狀服務區

• 每個細胞包含發射機(低功率)、接收機和控制單元

• 相鄰細胞為避免發生相互干擾或串音(crosstalk)現象，相鄰細胞會指配不同的頻率

• 每個細胞均擁有低功率傳送器，只要相鄰單元使用不同頻率

就不會互相干擾

• 不相鄰細胞可分配相同頻率，因低功率傳送器所能傳送的距

離有限，不會干擾到非相鄰地區


細胞(Cell)概念• 若干(K)細胞組成一個叢集(cluster)

• 同一cluster中的cell 使用不同頻率

• 對K-cell cluster，每個cell可用的頻率數目相同，假定此系統分配到的全部頻率數為

N，則每個cell分配到N/K個頻率

• 例如：AMPS系統中N=395則K=7為可以提供足夠的隔離使用相同頻率的最小樣式，

這也意味著平均每個細胞最多只能分配到

57個頻率


• 位在各個cluster中相同位置(例如同在左上方)的cells使用相同頻道

• K的數目越大，同頻率的微細胞距離相隔越遠

• 頻率重複使用(frequency reuse)

• 因彼此間距離很遠，雖使用相同頻率但不會互相干擾


1 2

3 4

5

6

7

1 2

3 4

5

6

7

2

1

1 2

3 4

5

6

7

1 2

3 4

5

6

7

1

1 1

1

2 2

2 2

3

3

3

3

4

4 4

4 5

5 5

5

6

6 6

6

7

7

7

7

8 8

8 8 9

9 9

9

10

10 10

10

11 11

11 11

12 12

12 12

K = 7 K = 12


增加系統容量的⽅方法• 增加新的頻道數目

• 一個系統在一個地區架設完後，開始時並未使用全部頻道，當使用者成長時，

系統可隨時加入新的頻道以供使用

• 頻率借用

• 在一些簡單的狀況中，被阻塞的細胞可使用相鄰細胞的頻率，所以頻率可以動

態地指定到不同的細胞中


• 細胞分向

• 將細胞區分成一些廣角的扇形區域，每個扇形區域擁有一組特定頻道，一

般每個細胞被切個成3至6個扇形區域

• 基地台的每個扇形區域上有一個指向性天線做傳輸信號之用



• 細胞分割

• 當某細胞服務區的話務量不斷成長到一定數量，導致細胞頻道

數提供的服務品質無法維持原有的標準，該細胞就必須進行細

胞分割

• 每次減少細胞大小時

• 基地台和行動單元也必須降低發射功率

• 換手(hand off)的動作也相對的愈來愈頻繁

• 分割細胞以提供更大容量時，半徑依比例F減少時，會以F 的比例減少涵蓋的區域和增加基地台的數目

• 當細胞變得很小時(微細胞)，天線會由較高的建築物或山丘的頂端，搬移到建築物頂端或大型建築物的一面牆上，最後則是

到了街燈柱上

• 微細胞在擁塞地區的街道、高速公路及大型建築物的內部尤其

有用

2



Cellular Network Standards

• Cellular Network Standard Bodies

• The 3rd Generation Partnership Project (3GPP) [Dec. 1998]

• The 3rd Generation Partnership Project 2 (3GPP2) [Dec. 1998]


3GPP• A collaboration between groups of

telecommunications associations, known as the Organizational Partners.

• The initial scope of 3GPP

• Make a globally applicable third-generation (3G) mobile phone system specification based on evolved Global System for Mobile Communications (GSM) specifications within the scope of the International Mobile Telecommunications-2000 (IMT-2000) project of the International Telecommunication Union (ITU).


• The scope was later enlarged to include the development and maintenance of

• The Global System for Mobile Communications (GSM) including GSM evolved radio access technologies (e.g. General Packet Radio Service (GPRS) and Enhanced Data Rates for GSM Evolution (EDGE))

• An evolved third Generation and beyond Mobile System based on the evolved 3GPP core networks, and the radio access technologies supported by the Partners (i.e., UTRA both FDD and TDD modes).

• An evolved IP Multimedia Subsystem (IMS) developed in an access independent manner

• 3GPP standardization encompasses Radio, Core Network and Service architecture.


3GPP2• A collaboration between telecommunications

associations to make a globally applicable third generation (3G) mobile phone system specification within the scope of the ITU's IMT-2000 project.

• The standardization group for CDMA2000, the set of 3G standards based on the earlier cdmaOne 2G CDMA technology.

• Ultra Mobile Broadband (UMB) was a 3GPP2 project to develop a fourth-generation successor to CDMA2000.

• In November 2008, Qualcomm, UMB's lead sponsor, announced it was ending development of the technology, favoring LTE instead.


3GPP vs. 3GPP2• 3GPP is the standard body behind the Universal Mobile

Telecommunications System (UMTS) that is the 3G upgrade to GSM networks

• 3GPP2 is the standard body behind the competing 3G standard CDMA2000 that is the 3G upgrade to cdmaOne networks used mostly in the United States (and to some extent also in Japan, China, South Korea and India).

• GSM/GPRS/EDGE/W-CDMA is the most widespread wireless standard in the world.

• A few countries (such as China, the United States, India, South Korea and Japan) use both sets of standards, but most countries use only the GSM family.


Cellular Network Standards


3GPP Standards (Releases)


Generations of Mobile Communication Systems

• 1G (analog, voice)

• NMT (Nordic Mobile Telephone) 900 system, 1981

• Introduced by Ericsson Radio System AB and deployed in Scandinavia

• AMPS (Advanced Mobile Phone Service), 1984

• Introduced by AT&T in North America


• 2G (digital, voice (major), data (minor))

• GSM (Global System for Mobile Communications)

• 1992, Phase I GSM, 1996, Phase II GSM

• cdmaOne (Interim Standard IS-95), 1993

• D-AMPS (Interim Standard IS-136), 1994

• PHS (Personal Handy phone System)


• 2.5G

• GSM+

• HSCSD (High Speed Circuit Switched Data，HSCSD)

• GPRS (General Packet Radio Service，GPRS)

• CDMA2000 1x

• 2.75G

• GSM++

• EDGE (Enhanced Data rates for Global Evolution)


• 3G (IMT-2000)

• UMTS (Universal Mobile Telecommunication System) (UTRAN)

• W-CDMA(Wideband CDMA)

• WCDMA-FDD

• WCDMA-TDD,

• TD-SCDMA (Time Division - Synchronous CDMA)

• CDMA2000 1xEV-DO Rev. 0


• 3.5G (data, multimedia)

• HSDPA (High-Speed Downlink Packet Access)

• CDMA2000 1xEV-DO Rev. A

• 3.75G

• HSUPA (High-Speed Uplink Packet Access)

• CDMA2000 EV-DO Rev. B


• 3.9G

• Mobile WiMAX (IEEE 802.16e)

• HSPA+

• LTE (Long Term Evolution) (E-UTRA)

• 4G (IMT Advanced)

• LTE-Advanced (E-UTRA)

• WiMAX-Advanced (WiMAX2, IEEE 802.16m)


Mobile Communication Systems

• GSM

• GPRS

• UMTS / WCDMA

• WiMAX

• LTE


GSM (Global System for Mobile Communications)

• 數位蜂巢式(cellular)行動電話系統

• 由歐洲郵政電信組織(CEPT)及其後繼者歐洲電信標準協會(ETSI)於1983年開始發展

• 目標：提供一套橫跨歐洲國家的相容性行動電話服務


GSM System Architecture



• Terms

• NSS：網路及交換子系統(Network and Switch Subsystem)

• MSC：行動交換中心(Mobile Switching Center)

• BSS：基地台子系統(Base Station Subsystem)

• BSC：基站控制台(Base Station Controller)

• BTS：基地收發台(Base Transceiver Station)

• MS：手機(Mobile Station)

• ME：手機通訊模組(Mobile Equipment)

• SIM：使用者認証模組(Subscriber Identity Module)


GPRS System Architecture



UMTS / WCDMA System Architecture


IEEE 802.16 WiMAX (Worldwide Interoperability for Microwave Access)

• A telecommunications technology aimed at providing wireless data over long distances in a variety of ways, from point-to-point links to full mobile cellular type access

• Enable the delivery of last mile wireless broadband access as an alternative to cable and DSL


WiMAX for Fixed and Mobile Access


WiMAX Consumer Last Mile


WiMAX Backhaul for Business


WiMAX Nomadic / Portable


IEEE 802.16 Operation Modes /Topologies

• Point to MultiPoint (PMP) / star topology

• Mesh mode / mesh topology

• Mobile Multihop Relay (MMR) / tree topology

BS：Base StationSS：Subscriber Station fixed station MS (Mobile Station) MSS (Multiple Subscriber Station)RS：Relay station


IEEE 802.16 Relevant Standards

• IEEE 802.16d (2004) basic fixed mode- standard

• IEEE 802.16e (2005) (Mobile WiMAX)


• IEEE 802.16j Mobile Multihop Relay (MMR)

• New relay networking protocols

• Multi-hop relay connections between SS/MS and BS

• Actually not mesh mode but tree topology

• IEEE 802.16m advanced air interface for WiMax (WiMax2)

• 100 Mbps for mobile applications

• 1 Gbps for fixed applications


WiMAX Network Reference Model


WiMAX Logical Network Entities

• Mobile Station (MS)

• Access Service Network (ASN)

• Base station (BS)

• ASN gateway (ASN-GW)

• Connectivity Service Network (CSN)


Mobile Station (MS)• Generalized user

equipment set (both mobile and fixed device terminals)

• Provide wireless connectivity between a single or multiple hosts and the WiMAX network


Access Service Network (ASN)

• A complete set of network functions required to provide radio access to MS

• Layer 2 (L2) connectivity with the MS according to IEEE 802.16 standards

• Transfer of authentication, authorization, and accounting (AAA) messages to the home network service provider (HNSP)

• Relay functionality for establishing layer 3 (L3) connectivity with MS (i.e., IP address allocation)


• Base station (BS)

• Primarily consists of radio related functions of an ASN interfacing with an MS over-the-air link according to MAC and PHY specifications

• ASN gateway (ASN-GW)

• An aggregation of centralized functions related to QoS, security, and mobility management for all the data connections

• Hosts functions related to IP layer interactions with CSN

• Interacts with other ASNs in support of mobility


Connectivity Service Network (CSN)• A set of network functions that

provide IP connectivity services to WiMAX subscriber(s)

• The CSN may further comprises network elements such as routers, AAA proxy /servers, home agent, and user databases as well as interworking gateways or enhanced network servers to support multicast and broadcast services and location-based services


LTE (Long Term Evolution) / SAE (System Architecture Evolution)

• LTE / SAE

• E-UTRAN (Evolved UTRAN) on the access side

• E-UTRAN is also known as LTE

• EPC (Evolved Packet Core) on the core side

• EPC is also known as SAE (System Architecture Evolution)


Network Architecture of LTE


SAE (EPC) Architecture – Functions per Element

• MME (Mobility Management Entity)

• Manages and stores the UE control plane context, generates temporary id, UE authentication, authorization, mobility management

• UPE (User Plane Entity)

• Manages and stores UE context, ciphering, mobility anchor, packet routing and forwarding, initiation of paging

• 3GPP anchor (Serving Gateway, S-GW)

• Mobility anchor between 2G/3G and LTE

• SAE anchor (PDN Gateway, P-GW)

• Mobility anchor between 3GPP and non 3GPP (I-WLAN, etc)


Evolved Packet Core – All-IP core for LTE

•Serving Gateway (SG-W)•Packet Data Network (PDN) Gateway (PGW)•Mobility Management Entity (MME)•Policy and Charging Rules Function (PCRF)[A new converged architecture to allow the optimization of interactions between the Policy and Rules functions.]


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Overview of Mobile Communication Systems