IMT IMT-2000 stands for IMT: International Mobile Communications 2000: the frequency range of 2000 MHz and the year 2000

Transcription

1 IMT-2000 IMT-2000 stands for IMT: International Mobile Communications 2000: the frequency range of 2000 MHz and the year 2000 In total, 17 proposals for different IMT-2000 standards were submitted by regional SDOs to ITU in proposals for terrestrial systems and 6 for mobile satellite systems (MSSs). All 3G standards have been developed by regional standard developing organizations (SDOs). Evaluation of the proposals was completed in 1998, and negotiations to build a consensus among different views were completed in mid All 17 proposals have been accepted by ITU as IMT-2000 standards. The specification for the 1 Radio Transmission Technology (RTT) was released at the end o999.

2 IMT-2000 The (IMT-2000), consists of 3 operating modes based on Code Division Multiple Access (CDMA) technology. 3G CDMA modes are most commonly known as: CDMA2000, WCDMA (called UMTS) and TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) 2

3 High-Speed Packet Data Services 2 Mbps in fixed or in-building environments (very short distances, in the order of metres) 384 kbps in pedestrian or urban environments 144 kbps in wide area mobile environments Variable data rates in large geographic area systems (satellite) 3

4 4

5 Network Elements from UMTS UMTS differs from GSM Phase 2+ (GSM +GPRS) mostly in the new principles for the air interface transmission WCDMA instead of TDMA/FDMA Therefore a new RAN (Radio Access Network) called: UTRAN (UMTS Terrestrial Radio Access Network) must be introduced with UMTS Only minor modifications are needed in the CN (Core Network) to accommodate the change 5

6 UTRA: UMTS Terrestrial Radio Access The most significant change in REL. 99 was the UTRAN, a W-CDMA radio interface for land-based communications. UTRAN supports time (TDD) and frequency division duplex (FDD). The TDD mode is optimized for public micro and pico cells and unlicensed cordless applications. The FDD mode is optimized for wide-area coverage, i.e. public macro and micro cells. Both modes offer flexible and dynamic data rates up to 2 Mbps. 6

7 UMTS architecture UTRAN (UTRA NETWORK) Radio Network Subsystem (RNS) UE (User Equipment) CN (Core Network) UE Uu UTRAN Iu CN 7

8 UTRAN Two new network elements are introduced in UTRAN RNC Node B UTRAN is subdivided into individual radio network systems (RNSs), where each RNS is controlled by an RNC. The RNC is connected to a set of Node B elements, each of which can serve one or several cells. 8

9 UTRAN architecture RNS RNC: Radio Network Controller RNS: Radio Network Subsystem UE 1 Node B I ub I u RNC CN UE 2 Node B UTRAN comprises several RNSs UE 3 Node B can support FDD or TDD or both Node B I ur Node B I ub RNC RNC is responsible for handover decisions requiring signaling to the UE Node B RNS Cell offers FDD or TDD

10 UTRAN functions Admission control Congestion control Radio channel encryption Handover Radio network configuration Channel quality measurements Radio resource control Data transmission over the radio interface Outer loop power control (FDD and TDD) Channel coding 10

11 Core network The Core Network (CN) and the Interface I u, are separated into two logical domains: Circuit Switched Domain (CSD) Circuit switched service incl. signaling Resource reservation at connection setup GSM components (MSC, GMSC, VLR) I u CS Packet Switched Domain (PSD) GPRS components (SGSN, GGSN) I u PS BTS A bis BSS I u VLR Node BTSB Node B BSC MSC I u CS EIR GMSC HLR AuC GR PSTN Node B Node B I ub RNC RNS SGSN I u PS G n GGSN G i CN

12 Access method CDMA CDMA (Code Division Multiple Access) all terminals send on the same frequency probably at the same time and can use the whole bandwidth of the transmission channel each sender has a unique random number, the sender XORs the signal with this pseudo random number the receiver can tune into this signal if it knows the pseudo random number, tuning is done via a correlation function

13 Spreading and scrambling of user data Constant chip rate of 3.84 Mchip/s Different user data rates supported via different spreading factors higher data rate: less chips per bit and vice versa User separation via unique, quasi orthogonal scrambling codes users are not separated via orthogonal spreading codes much simpler management of codes: each mobile can use the same orthogonal spreading codes data 1 data 2 data 3 data 4 data 5 spr. code 1 spr. code 2 spr. code 3 spr. code 1 spr. code 4 scrambling code 1 scrambling code 2 sender 1 sender 2

14 Length 1 Ri 1 Ri 1 R c R R c i SPREADING FACTOR Length 1 Rc

15

16 DS-CDMA= Direct Sequence Code Division Multiple Access

17 3.84 Mchip/s

18 CDMA in theory Sender A sends A d = 1, key A k = (assign: 0 = -1, 1 = +1) sending signal A s = A d * A k = (-1, +1, -1, -1, +1, +1) Sender B sends B d = 0, key B k = (assign: 0 = -1, 1 = +1) sending signal B s = B d * B k = (-1, -1, +1, -1, +1, -1) Both signals superimpose in space interference neglected (noise etc.) A s + B s = (-2, 0, 0, -2, +2, 0) Receiver wants to receive signal from sender A apply key A k bitwise (inner product) A e = (-2, 0, 0, -2, +2, 0) A k (-2, 0, 0, -2, +2, 0) (-1, +1, -1, -1, +1, +1)= = 6 result greater than 0, therefore, original bit was 1 receiving B B e = (-2, 0, 0, -2, 2, 0) B k ( -2, 0, 0,- 2,- 2, 0) (1, 1, -1, +1, -1, +1) = -6, i.e. 0

19 data A key A key sequence A data key CDMA on signal level I A d A k signal A A s Here the binary 0 is assigned a positive value, The binary 1 a negative value! Real systems use much longer keys resulting in a larger distance between single code words in code space.

20 CDMA on signal level II signal A +1-1 A s data B B d key B key sequence B data key signal B B k B s A s + B s

21 CDMA on signal level III data A +2 A s + B s A d A k (A s + B s ) * A k 0-2 integrator output comparator output 1 0 1

22 CDMA on signal level IV data B B d A s + B s B k (A s + B s ) * B k integrator output comparator output 1 0 0

23 CDMA on signal level V +2 A s + B s 0-2 wrong key K (A s + B s ) * K integrator output comparator output (0) (0)?

24 OSVF coding Ortogonal Variable Spreading Factor Codes Recursive rule X,X X 1,1,1,1 1,1 1,1,-1,-1 1 X,-X 1,-1,1,-1 SF=n SF=2n 1,-1 1,-1,-1,1 1,1,1,1,1,1,1,1 1,1,1,1,-1,-1,-1,-1 1,1,-1,-1,1,1,-1,-1 1,1,-1,-1,-1,-1,1,1 1,-1,1,-1,1,-1,1,-1 1,-1,1,-1,-1,1,-1,1 1,-1,-1,1,1,-1,-1,1 1,-1,-1,1,-1,1,1, SF=1 SF=2 SF=4 SF=8

25 Support of mobility: macro diversity UE Node B Multicasting of data via several physical channels Enables soft handover FDD mode only Uplink simultaneous reception of UE data at several Node Bs Node B RNC CN Downlink Simultaneous transmission of data via different cells

26 Transmit Power Control is essential Near far problem despreading MS MS Node B Power control despreading MS MS Node B Transmit Power Control Minimize the Tx power More secure Increase the system capacity

27 Frequency Allocation FDMA / TDMA CDMA f 2 f 2 f 3 f 3 f 2 f 2 f 2 f 3 f 3 f 3 f 2 f 2 f 3 f 3 A case of 3 cell repetitions Same frequency in all cells. 27

28 UMTS protocol stacks (user plane) Circuit switched UE U u UTRAN I u CS 3G MSC apps. & protocols RLC MAC RLC MAC SAR AAL2 SAR AAL2 radio radio ATM ATM Packet switched UE U u UTRAN I u PS 3G SGSN apps. & protocols IP, PPP, PDCP RLC MAC radio PDCP GTP GTP GTP RLC UDP/IP UDP/IP UDP/IP MAC radio AAL5 ATM IP tunnel AAL5 ATM L2 L1 G n 3G GGSN IP, PPP, GTP UDP/IP L2 L1

29 EDGE Enhanced Data rates for GSM Evolution ECSD - Enhanced CSD (Circuit Switched Data) EGPRS - Enhanced GPRS For higher data rates New coding and modulation schemes The base stations need to be up dated EGPRS up to 384 kbps (48 kbps per time slot) ECSD 28.8 kbps 29

30 Modulation 30

31 The Beauty Contest Ten companies asked for one out of four licences Licences were given to Vodaphone Tele2 Hi3G Orange The incumbent, Telia, was not given a licence!!! 31

32 UMTS in Sweden The licensees have to cover inhabitants. Two joint ventures: Svenska UMTS nät - Tele2 and Telia Telia and Tele2 have established a joint venture, Svenska UMTS nät, with a common 3G network. 3GIS Telenor and 3* To meet the regulatory requirements, Telenor and 3 has build individual networks, and each has to cover 30% of the population. Telenor and 3 have established a joint venture, 3G Infrastructure Services (3GIS) with a common shared network. This network covers approximately 70% of the population. 32 Björkdahl & Bohlin

33 Network coverage Theoretically it is possible to cover inhabitants by covering km² of Sweden s surface area. (Swedish total area is km².) Theoretical level corresponds to a coverage of 5% of the Swedish area. In practice, it seems reasonable that the operators will aim for a total coverage of around km². This corresponds to a coverage of 41% of the Swedish surface area. The operators will be able to cover all urban areas and 84% of the inhabitants by covering around km². This corresponds to a coverage of 2.7% of the Swedish surface area. 33

34 Investment for an average operator Comparing Germany, United Kingdom and Sweden The table shows the average 3G investment per capita per year, including applicable license fees, in Sweden, Germany and the UK for an average operator in each country, for the entire license duration. 3.8 USD 6.2 USD 7.5 USD 1 USD = 8 SEK 34

35 Summary of main findings The average 3G network investment per operator is estimated to be SEK 6.1 billion. The total 3G network investment in Sweden is estimated to be SEK 24 billion. If the Swedish joint ventures co-operate in rural areas the total 3G network investment is estimated to be SEK 19 billion. 35

36 End of Chapter 36