Macrocell Microcell Picocell

Universal Mobile Telecommunications System (UMTS) is a 3G technology that provides highspeed connection of up to 2 Mbps to support a wide variety of services, including multimedia services with different QoS requirements. As shown in Figure 11.1, UMTS evolved from 2G GSM technology and 2.5G GPRS. The effective bandwidth provided is up to 144 kbps for vehicular users, 384 kbps for mobile users, and up to 2 Mbps for static users. The recent UMTS Rel-5 added to previous releases (Rel-99 and Rel-4) the High-Speed Download Packet Access (HSDPA) technology. HSDPA adds an option of higher speeds of up to 10 Mbps required for multimedia applications.

Figure 11.1. UMTS Evolution

Figure 11.1. UMTS Evolution

Evolution Hsdpa

UMTS, which is also referred to as WCDMA (Wideband CDMA or Wideband Code Division Multiple Access), is part of IMT-2000 (International Mobile Telecommunication-2000) effort, which is designed to provide high-speed communication with high-quality multimedia services and global roaming support. The IMT-2000 effort is led by the ITU (International Telecommunications Union), formerly the CCITT (Consultative Committee for International Telephony and Telegraphy), is an international organization that sets communication standards and consists of more than 150 member countries.

The IMT-2000 effort strives to create a family of compatible standards that can be used worldwide for all mobile applications. This family is expected to support both circuit and packet switched applications and provides QoS support for multimedia traffic. This effort considered several proposals for both terrestrial and satellite communication, from which WCDMA and CDMA 2000 were selected for terrestrial communication.

UMTS has been introduced and evolved in several releases. Starting with Release 99 UMTS integrated GSM and GPRS such that previous investments in those networks can be preserved. UMTS Terrestrial Radio Access Network (UTRAN) is UMTS's radio access network that provides the communication path between the mobile station and the 3G core network through the Iu interface. UMTS shares the same core network as GPRS except the UTRAN radio interface, which is newly designed (see Figure 11.2). Therefore, GPRS and UMTS are fully harmonized.

Figure 11.2. GPRS and UMTS

Figure 11.2. GPRS and UMTS

Frequency Division Fdd Gsm

UTRAN supports two modes of operation: 1) Frequency Division Duplex (FDD), where uplink transmissions (from the mobile stations to UTRAN) and downlink transmissions (from UTRAN to the mobile stations) operate simultaneously using two separate frequency bands; and 2) Time Division Duplex (TDD), where uplink and downlink transmissions operate interchangeably in different time periods on the same frequency band.

In UTRAN FDD mode, UTRAN deploys Wideband Code Division Multiple Access (WCDMA), whereas in UTRAN TDD mode, UTRAN deploys Time Division-Code Division Multiple Access (TD-CDMA). Figure 11.3 shows UMTS coverage scenarios. FDD mode, which is geared toward wide area coverage (i.e., public macro and micro cell), supports high user mobility and data rates of up to 384 kbps. TDD, which is geared toward smaller geographical areas (i.e., public micro and pico cells), supports data rates of up to 2 Mbps and slow user mobility (i.e., cordless phones). In order to operate in both wide and local areas, a mobile station or user equipment (UE) should support both TDD and FDD modes.

Figure 11.3. UMTS Geographical Coverage

Figure 11.3. UMTS Geographical Coverage

Pico Cell Umts
Pico Cell 100 m. Macro Cell 5-lÛkm Micro Cell 0.5 km. Gtobal Cell > 1Û km

In this book we focus on UMTS Rel-5, which is presented in the following documents:

• TS 23.002 3rd Generation Partnership Project; Technical Specification Group Services and Systems Aspects; Network Architecture (Release 5)

• TS 25.301 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Radio Interface Protocol Architecture (Release 5)

• TS 25.401 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; UTRAN Overall Description (Release 5)

• TS 25.302 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Services provided by the physical layer (Release 5)

• TS 25.211 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Physical channels and mapping of transport channels onto physical channels (FDD) (Release 5)

• TS 25.321 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; MAC Protocol Specification (Release 5)

• TS 25.322 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Radio Link Control (RLC) Protocol Specification (Release 5)

• TS 25.323 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Packet Data Convergence Protocol (PDCP) Specification (Release 5)

• TS 25.331 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Radio Resource Control (RRC); Protocol Specification (Release 5)

• TS 25.308 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; High-Speed Downlink Packet Access (HSDPA); Overall Description; Stage 2 (Release 5)

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Responses

  • Pamphila
    Do picocells support multiple frequencies simultaneously?
    5 years ago

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