Next generation wireless systems and networks phần 4 potx

140 3G MOBILE CELLULAR TECHNOLOGIES Link adaptive modulation The link adaptive modulation scheme is another important feature introduced in the CDMA2000 1xEV system. In fact, the 1xEV forward link offers a range of different data rates. The data rates match the range of channel conditions experienced in a typical cellular or PCS networks. QPSK modulation is used to achieve 38.4 kbps through 1228.8 kbps data rates (with the exception of 921.6 kbps), 8PSK for 921.6 kbps and 1843.2 kbps and 16QAM for 1228.8 kbps and 2457.6 kbps. Table 3.12 shows the correspondence of adaptive modulation schemes, code rate, transmission rate, number of slots, and so on, in the CDMA2000 1xEV Forward Link. The CDMA2000 1xEV forward link supports dynamic data transmission rates. The AT constantly measures the channel carrier to the interference (C/I) ratio, and then requests the appropriate data rate for the channel conditions every 1.67 ms. The AP receives the AT’s request for a particular data rate, and encodes the forward link data at exactly the highest rate that the wireless channel can support at the requested instant. Just enough margin is included to allow the AT to decode the data with a low erasure rate. In this way, as the subscriber’s application needs and channel conditions change, the optimum data rate is determined and served dynamically to the user. In summary, the following steps are performed: • Accurate and rapid measurement of the received C/I ratio from the set of best serving sectors • Selection of the best serving sector • Request of transmission at the highest possible data rate that can be received with high reliability given the measured C/I • Transmission from the selected sector, and only from the selected sector, at the requested data rate. The AT continuously updates the AP on the DRC channel, indicating a specified data rate to be used on the forward link. The DRC is sent with a Walsh Cover, which indicates which sector should transmit. CDMA2000 1xEV combines the functions of the cdmaOne Sync and Paging overhead channels into a single Control Channel, which is transmitted once every 413.17 ms for a duration of 13.33 ms. This forward link control channel creates notable efficiencies. FTC and Control Channel can be transmitted in a span of 1 to 16 slots. When more than one slot is used, the transmit slots use a 4-slot interlacing technique to further enhance forward link efficiency, as shown in Figure 3.7. For example, data sent at 153.6 kbps is sent in four slots and each slot of data is sent twice to increase the probability of receiving the data. By interlacing the data with every fourth slot, the AT can notify the AP of each slot of data it receives. If the AT is able to decode the data on the first attempt, then it transmits an ACK to the AP. The AP cancels the second slot if the ACK is received prior to its Table 3.12 CDMA2000 1xEV adaptive modulation schemes, code rate, transmission rate, number of slots in forward link Data rate (kb/s) 38.4 76.8 153.6 307.2 307.2 614.4 614.4 921.6 1228.8 1228.8 1843.2 2457.6 Modem QPSK QPSK QPSK QPSK QPSK QPSK QPSK 8PSK QPSK 16QAM 8PSK 16QAM Encoded 1024/ 1024/ 1024/ 1024/ 2048/ 1024/ 2048/ 3072/ 2048/ 4096/ 3072/ 4096/ packet length (bits/ms) 26.67 13.33 6.67 3.33 6.67 1.67 3.33 3.33 1.67 3.33 1.67 1.67 Code rate 1/5 1/5 1/5 1/5 1/3 1/3 1/3 1/3 1/3 1/3 1/3 1/3 No.ofslots1684241221 2 1 1 3G MOBILE CELLULAR TECHNOLOGIES 141 Selection of best serving sector based on measured C/I Fwd Data Access Point 1 Access Point 2 Access Terminal measures (C/I) 2 > (C/I) 1 Time 1 Time 2 Requests data from AP2 at data Rate R Figure 3.9 Dynamic data rate served based on real-time C/I measurement achieved in CDMA2000 1xEV air-link. transmission. The system has now increased the throughput to the user and may use the additional slots to serve other users. The combination of these features and the ability to transmit two bits per Hertz in a 1.25 MHz band increases bandwidth efficiency and overall system capacity. Figure 3.9 shows a conceptual diagram for CDMA2000 1xEV to achieve dynamic data rate served based on real-time C/I measurement. 3.1.7 Scheduling It is to be noted that CDMA2000 1xEV is optimized for packet data services, in which all terminals do not necessarily demand equal service. Some applications require higher data rates, while others do not. The user’s channel condition (i.e., the carrier to interference ratio) is also an important factor in determining the data rate that a given user can attain. The 1xEV system takes advantage of the wireless channel variability, which results in variations of the requested rate over a period of time. The scheduler resides at the BS and takes the data rates requested by different MSs into account. The scheduling algorithm decides which MS is served with the requested data rate at any given instant. The scheduler is weighted to serve users that are improving their signal quality and weighted against users that are experiencing signal degradation. Occasionally, the users may not be served for periods of milliseconds when their requested rates are lower. By the scheduler selecting the optimal time to transmit data to a user, the user’s overall moving average throughput is higher than if they were served on a first-in-first-out basis. Please note that the priority in the scheduler is based on a combination of the following: the C/I as well as the duration since the last time a user has been served. Disadvantaged users with low C/I accumulate credits with the scheduler, thereby increasing their priority in the system and improving their throughput. CDMA2000 1xEV uses Proportional Fairness Scheduling for packet scheduling. This algorithm uses a different notion of fairness known as proportional fairness. The Proportional Fairness Scheduler maximizes the user’s moving average throughput, which improves their experience. The algorithm used by the Proportional Fairness Scheduler takes advantage of variable bit rate that 1xEV uses to deliver data. The algorithm maintains a running average of each user’s RF conditions and attempts to deliver data at the requested peak rates, avoiding delivering data when the requested rates are at their lowest points. For example, a particular user has RF conditions that support an average of 614.4 kbps. The changing RF environment surrounding the user causes the RF conditions to oscillate between low and HDRs, with the average being 614.4 kbps. The scheduler’s histogram of each user calculates the moving average and serves data when the DRC is equal to or greater than 614.4 kbps, and not 142 3G MOBILE CELLULAR TECHNOLOGIES at the lower short term rates. The result is that the user’s actual data throughput is higher than the running average of the requested data rates. In summary, the Proportional Fairness Scheduler takes advantage of the channel variation over a short period to increase throughput and maintain the grade of service fairness over longer periods of time. 3.1.8 Reverse Link The 1xEV reverse link structure consists of fixed size physical layer packets (16 slots, 26.67 ms duration). Each slot is just a unit of time. The Reverse Link is different from the forward link physical layer, which has variable modulation schemes in 1.67 ms units of time. 1xEV uses a pilot-aided, coherently demodulated reverse link. Traditional cdmaOne power control mechanisms and soft handoffs (SHOs) are supported on the reverse link. A 1xEV AT may transmit at rates from 9.6 kbps to 153.6 kbps on the reverse link. The 1xEV Reverse Channel consists of the Access Channel and the TCH. The Access channel consists of a Pilot Channel and a Data Channel. The TCH consists of a Pilot Channel, a MAC Channel, an Acknowledgment (ACK) Channel, and a Data Channel. The Traffic MAC Channel contains a Reverse Rate Indicator (RRI) Channel and a DRC Channel. The Access Channel is used by the AT to initiate communication with the Access Network or to respond to an AT directed message. The Access Channel consists of a Pilot Channel and a Data Channel. An access probe consists of a preamble followed by an Access Channel data packet. During the preamble transmission, only the Pilot Channel is transmitted. During the Access Channel data packet transmission, both the Pilot Channel and the Data Channel are transmitted. The reverse link TCH is used by the AT to transmit user specific traffic or signaling information to the Access Network. The reverse link TCH consists of a Pilot Channel, a MAC Channel, an ACK Channel, and a Data Channel. The MAC Channel contains a DRC Channel and an RRI Channel. The ACK Channel is used by the AT to inform the Access Network whether the data packet transmitted on the FTC has been successfully received or not. The total reverse link capacity is 200 kbps/sector (2.2 times that of IS-95A). This increased capacity is achieved by taking advantage of turbo coding, gaining diversity from the longer packet size (26.67 ms), and the pilot channel. Reverse link channel structure Figure 3.10 shows the Reverse Traffic Channel structure of the 1xEV standard. There are four orthog- onal code-division multiplexed channels. As shown in Figure 3.10, the Pilot/RRI Channel is time multiplexed so that the RRI channel is transmitted during 256 chips at the beginning of every slot (1.66 ms). The 3-bit RRI symbol transmitted every frame (16 slots), is encoded using a 7-bit sim- plex codeword. Each codeword is repeated 37 times over the duration of the frame, while the last three code symbols are not transmitted. The DRC symbols (four bits indicating the desired rate) are encoded using 16-ary biorthogonal code. Each code symbol is further spread by one of the 8-ary Walsh functions in order to indicate the desired transmitting sector on the forward link. The DRC message is transmitted with half-slot offset relative to the slot boundary. The reason is to minimize prediction delay while providing enough time for processing at the desired sector before transmission on the forward link starts on the next slot. A DRC message indicating the desired forward link data rate and transmitting sector may be repeated over DRC Length slots, a user-specific parameter set by the access network. The ACK Channel is BPSK modulated in the first half-slot (1024 chips) of an active slot. A “0” bit is transmitted on the ACK Channel if a data packet has been successfully received on the FTC; otherwise a “1” bit is transmitted. Transmissions on the ACK Channel only occur if the AT detects a data packet directed to it on the FTC. For a Forward Traffic Channel data packet transmitted in slot 3G MOBILE CELLULAR TECHNOLOGIES 143 ACK Channel Relative Gain DRC Channel Relative Gain Data Channel Relative Gain D B C A Σ Quadrature Spreading (Complex Multiply) I = I'PN I - Q'PN Q Q = I'PN Q - Q'PN I I' Q' Q I PN I PN Q P Q Q-Channel Short PN Sequence P I I-Channel Short PN Sequence U Q Q-Channel User Long-Code PN Sequence U I I-Channel User Long-Code PN Sequence Baseband Filter Baseband Filter cos(2pf c t) sin(2pf c t) S(t) Walsh Cover Decimator by Factor of 2 Σ Σ (+ −) × × × ×× × × × × × Simplex Encoder Biorthogonal Encoder Encoder Codeword Repetition (Factor = 37) Codeword Repetition (Factor = 2) Bit Repetition (Factor = 128) Interleaved Packet Repetition Channel Interleaver 7 Binary Symbols per Physical Layer Packet 259 Binary Symbols per Physical Layer Packet 256 Binary Symbols per Physical Layer Packet 128 Binary Symbols per Slot 16 Binary Symbols per Active Slot 128 Binary Symbols per Slot (Transmitted in 1/2 Slot) 8 Binary Symbols per Active Slot DRC Symbols One 4-Bit Symbol per Active Slot ACK Channel 1 Bit per Slot RRI Symbols One 3-Bit Symbol per 16-Slot Physical Layer Packet Puncture Last 3 Symbols Signal Point Mapping 0 →+1 1 → −1 Signal Point Mapping 0 →+1 1 → −1 Signal Point Mapping 0 →+1 1 → −1 Signal Point Mapping 0 →+1 1 → −1 Pilot Channel (All O's) 1.2288 Mcps 1.2288 Mcps C 1.2288 Mcps B 1.2288 Mcps A D TDM 7:1 W 8 16 = (+ + + + + + + + − − − − − − − −) W 0 16 = (+ + + + + + + + + + + + + + + +) W 4 8 = (+ + + + − − − −) W 2 4 = (++−−) Walsh Cover W i 8 . i = 0, ,7 Data Channel Physical Layer Packets Physical Layer Packets Bits 256 512 1024 2048 4096 Rate(kbps) 9.6 19.2 38.4 76.8 153.6 Code Rate 1/4 1/4 1/4 1/4 1/2 Symbols 1024 2048 4096 8192 8192 Rate(ksps) 38.4 76.8 153.6 307.2 307.2 Rate(ksps) 307.2 307.2 307.2 307.2 307.2 Figure 3.10 Reverse traffic channel structure in CDMA2000 1xEV air-link. 144 3G MOBILE CELLULAR TECHNOLOGIES n, the corresponding ACK Channel bit is transmitted in slot n + 3 on the Reverse Traffic Channel. The three slots of delay allow the terminal to demodulate and decode the received packet before transmitting on the ACK Channel. The Data Channel supports data rates from 9.6 to 153.6 kbps with 16-slot packets (26.66 ms). The packet is encoded using either rate 1/2 or rate 1/4 Parallel Turbo Code as specified in 1xEV. The code symbols are bit-reversal interleaved and block repeated to achieve the 307.2 ksps modulation symbol rate. The Pilot/RRI, DRC, ACK, and Data Channel modulation symbols are each spread by an appropri- ate orthogonal Walsh function as shown in Figure 3.10. Before quadrature spreading (see Figure 3.10), the Pilot/RRI and ACK Channels are scaled and combined to form the in-phase component. Simi- larly, the Data and DRC Channels are scaled and combined to form the quadrature component of the baseband signal. Reverse link power control (both open and closed loops) is applied to the Pilot/RRI Channel only. The powers allocated to the DRC, ACK and Data channels are adjusted by a fixed gain relative to the Pilot/RRI Channel in order to guarantee the desired performance of these channels. For example, the relative gain of the Data Channel increases with the data rate so that the received Eb/Nt is adjusted to achieve the required packet error rate (PER). The reverse link provides an RRI, which aids the AP in determining the rate at which the reverse link is sending data. The RRI is included as the preamble for reverse link frames, indicating the rate at which the data was sent. Figure 3.11 shows the 1xEV reverse channel structure. The data rates supported in CDMA2000 1xEV reverse link are listed in Table 3.13, which actually shows the physical layer parameters of the reverse link channels. Q-Phase User 1 Traffic Packet Q-Phase User 1 DRC I-Phase User 1 ACK I-Phase User 1 Pilot/RRI ½ Slot RRI 256 chips 256 chips 1 Slot = 2048 Chips 16 Slot = 26.67 ms 16 Slot = 26.67 ms 16 Slot = 26.67 ms 16 Slot = 26.67 ms Pilot Channel 1.67 ms 1.67 ms 1.67 ms 1.67 ms Figure 3.11 Dynamic data rate served based on real-time C/I measurement achieved in CDMA2000 1xEV air-link. 3G MOBILE CELLULAR TECHNOLOGIES 145 Table 3.13 CDMA2000 1xEV reverse link modulation schemes, code rate, encoded packet length, number of slots Data Rates (kbps) 9.6 19.2 38.4 76.8 153.6 Modulation BPSK BPSK BPSK BPSK BPSK Encoded packet length (bits)/(ms) 256/26.67 512/26.67 1024/26.67 2048/26.67 4096/26.67 Code rate 1/4 1/4 1/4 1/4 1/2 No. of slots 16 16 16 16 16 3.1.9 CDMA2000 1xEV Signaling The CDMA2000 1xEV layered architecture enables a modular design that allows partial updates to protocols, software, and independent protocol negotiation. The following are the CDMA2000 1xEV protocol stack layers: • Physical Layer: The Physical Layer provides the channel structure, frequency, power output, modulation, and encoding specifications for the Forward and Reverse link channels. • MAC Layer: The Medium Access Control layer defines the procedures used to receive and transmit over the Physical Layer. • Security Layer: The Security Layer provides authentication and encryption services. • Connection Layer: The Connection Layer provides air-link connection establishment and main- tenance services. • Session Layer: The Session Layer provides protocol negotiation, protocol configuration, and session state maintenance services. • Stream Layer: The Stream Layer provides multiplexing of distinct application streams. • Application Layer: The Application Layer provides the Default Signaling Application for trans- porting 1xEV protocol messages and the Default Packet Application for transporting user data. The detail configuration of all different layers in CDMA2000 1xEV standard is shown in Figure 3.12. It is to be noted from the figure that the overall structure of the CDMA2000 1xEV layered architecture was designed according to the general OSI reference model of seven-layer archi- tecture. 7 However, we can see some differences between the standard OSI reference model and CDMA2000 1xEv layered architecture. First of all, the MAC layer has been extracted from the data link layer in the OSI model to become a stand-alone layer. The security layer in the CDMA2000 1xEV is a newly added layer, which does not enjoy the similar emphasis in the OSI reference model. Similarly, both the Connection layer and Stream layer in CDMA2000 1xEV layered architecture do not appear in the OSI reference model as independent layers, although part of their functionalities has been included in either the Transport layer or the Presentation layer. Next, we will explain the major functions of different layers in CDMA2000 1xEV standard. 7 More detailed discussions on the OSI reference model of seven-layer architecture is given in Section 2.5. 146 3G MOBILE CELLULAR TECHNOLOGIES Figure 3.12 Layered network architecture in CDMA2000 1xEV standard. Physical layer The functionalities of the physical layer are obvious, delivering physical signaling through the air-link channels without refering to the detailed interpretation of the digital signals. For those descriptions, readers may go back to the previous Subsection 3.1.8 and Subsection 3.1.6. MAC layer The MAC Layer is a key component to optimizing the efficiency of the airlink and allowing multiple access to the network in a most cost-effective way. It is comprised of four component protocols, each of which play a part in the transmission of data and system information over the air-link channels, as explained below: • Control Channel MAC Protocol: It governs the transmission by the Access Network and the subsequent reception by the AT of information on the Control Channel. The Control Channel packets are constructed from the Security Layer packets, and contain information controlling 3G MOBILE CELLULAR TECHNOLOGIES 147 the Access Network transmission and packet scheduling, the AT acquisition, and AT packet reception on the Control Channel. This protocol also adds the AT address to transmitted packets. The rules for Control Channel supervision are part of this protocol as well. • Access Channel MAC Protocol: It specifies the rules for sending messages on the Access Channel by the AT. This includes the timing as well as power requirements for the transmission. The AT communicates with the Access Network via the Access Channel prior to setting up a traffic connection. • FTC MAC Protocol: It enables the system to send a user’s data packets at optimal efficiency, by utilizing variable and fixed transmission rates and ARQ interlacing. The ARQ interlacing coupled with the DRC and ACK Channel provides the handshake to increase the AT’s data throughput performance, resulting in increased capacity of the system. The FTC MAC Protocol also provides the rules that the Access Network uses to interpret the DRC Channel and the rules the AT uses for DRC supervision. • Reverse Traffic Channel MAC Protocol: It is very similar to the traditional CDMA 1x MAC layer. The protocol transports the information sent by the AT to enable the Access Network in acquiring the Reverse Traffic Channel; and the Reverse Traffic Channel data rate selection. Security layer The Security Layer ensures the security of the connection between the AT and the Access Network. It utilizes the Diffie–Hellman key exchange 8 to ensure the intended device is authenticated on the Access Network, and that the connection is not hijacked. It is not intended to encrypt the user’s data. For complete security of the user’s data it is best to use an end-to-end method, that is, IP Security (IPSEC). IPSEC is a set of protocols developed by the IETF to support the secure exchange of packets at the IP layer. IPSEC has been widely deployed in order to implement Virtual Private Networks (VPNs). IPSEC supports two encryption modes: Transport and Tunnel. The Transport mode only encrypts the data portion (payload) of each packet, but leaves the header untouched. The more secure Tunnel mode encrypts both the header and the payload. On the receiving side, an IPSEC-compliant device decrypts each packet. The majority of today’s VPN services utilize IPSEC to encrypt and protect information end-to-end. The Security Layer provides the following functions: • Key Exchange: It provides the procedures followed by the Access Network and the AT to exchange security keys for authentication and encryption. The system uses the Diffie–Hellman Key Exchange method. • Authentication: It provides the procedures followed by the Access Network and the AT for authenticating traffic. • Encryption: It provides the procedures followed by the Access Network and the AT for encrypt- ing traffic. Connection layer The Connection Layer consists of several protocols that are optimized for packet data processing. When they are combined they efficiently manage the 1xEV airlink, reserve resources, and prioritize each user’s traffic. They are designed to enhance the user’s experience while at the same time bringing 8 Diffie–Hellman key exchange is a cryptographic protocol which allows two parties that have no prior knowl- edge of each other to jointly establish a shared secret key over an insecure communications channel. 148 3G MOBILE CELLULAR TECHNOLOGIES efficiency to the carrier network. Each protocol in the Connection Layer is introduced individually as follows: • AirLink Management Protocol activates one of the below mentioned three State Protocols based on the AT state. • Initialization State Protocol (AT has not yet acquired the network) performs the actions associ- ated with acquiring the 1xEV network. This includes network determination, pilot acquisition and system synchronization. • Idle State Protocol (AT has acquired the network, however it is not sending or receiving any data) monitors the location of the AT via the Route Update Protocol, provides procedures for the opening of a connection, and supports AT power conservation. • “Suspend Mode” is a new addition to the Idle State Protocol. Suspend Mode expedites the connection setup process. In the suspend mode period, the AT advertises to the network that it will be monitoring the Control Channel before going into slotted mode for a certain period of time; so that the Access Network can quickly assign a TCH to the AT, if needed, rather than going through the usual paging and assignment procedure. • Connected State Protocol (AT has an open connection with the network) performs the actions of managing the radio link between the AT and the Access Network (handoffs controlled by the Route Update Protocol), and the procedures leading to the close of the connection. • Route Update Protocol plays a key part in enabling soft and softer handoffs. The AT’s Route Update Protocol constantly reports to the Access Network, which AP and sector it is using, as well as potential neighboring sectors. This information is used by the Access Network in maintaining a stable and good quality radio link as the AT moves throughout the network. • Overhead Messages Protocol is unique owing to the fact that it is used by multiple protocols. It broadcasts essential parameters pertaining to the operation of other protocols over the Control Channel. It also specifies rules for supervision of these messages over the Control Channel. • Packet Consolidation Protocol is a key element to providing effective QoS to the user. It is responsible for consolidating packets and properly prioritizing them, according to their assigned QoS, for the forward link, and de-multiplexing them on the reverse link. The priority tagging is done at the Stream Layer. It is capable of prioritizing for multiple streams to a single user and multiple streams to many users. Session layer The Session Layer protocols provide a support system for the lower layers in the protocol stack. It enables the assignment of the UATI to the AT and configuration information that supports the lower layers. The negotiation of a set of protocols and their configurations for communication between the AT and the Access Network are controlled by this protocol. The Session Layer contains the following protocols: • Session Management Protocol provides the means to control the ordered activation of the other Session Layer protocols. In addition, this protocol ensures the session is still valid and manages closing the session, resulting in the efficient use of spectrum. • Address Management Protocol specifies procedures for the initial UATI assignment and main- tains the AT addresses. 3G MOBILE CELLULAR TECHNOLOGIES 149 • Session Configuration Protocol provides the means to negotiate and provision the protocols used during the session, and negotiates the configuration parameters for these protocols. Stream layer The Stream Layer tags all the information that is transmitted over the airlink. This includes user traffic as well as signaling traffic. Lower in the stack, these values are read by the Connection Layer’s Packet Consolidation Protocol. The two protocols jointly provide effective prioritization of signaling and user traffic. The Stream layer maps the various applications to the appropriate stream and multiplexes the streams for one AT. Stream 0 is always assigned to the Signaling Application. The other streams can be assigned to applications with different QoS requirements or other applications. Application layer The Application Layer is the top layer and is a suite of protocols that ensure reliability and low erasure rate over the airlink. The underlining principle of this layer is to increase the robustness of the 1xEV protocol stack. The Application layer has two sublayers, which are the Default Signaling Application that provides best effort and reliable transmission of signaling messages, and the Default Packet Application that provides reliable and efficient transmission of the user’s data. The Default Signaling Application Protocol has two sublayers: • Signaling Network Protocol (SNP) provides a message transmission service for signaling mes- sages. These messages are initiated by other protocols, which indicate the appropriate message to be transmitted for a specific function. • Signaling Link Protocol (SLP) is the transport for the SNP messages. SLP provides a fragmen- tation mechanism for signaling messages, along with reliable and best-effort delivery services. The fragmentation mechanism increases the efficiency of sending signaling messages that may be larger than a single frame. Default Packet Application Protocol provides reliable and efficient delivery of the user’s data at a low PER, suitable for higher layers (e.g., TCP, UDP), along with mobility management that allows the Access Network to know the location of a mobile at any instance. Default Packet Application Protocol is comprised of two protocols: • Radio Link Protocol (RLP): Data applications are not as delay sensitive as voice applications; therefore wireless Internet systems provide various mechanisms for error detection and data retransmission. The RLP layer delivers a frame error rate in the order of 10 −4 . The combination of RLP and TCP layers deliver an extremely low frame error rate, which is comparable with most land-line data systems today. The RLP protocol uses a NAK-based scheme, thereby reducing the amount of signaling. In addition, the 1xEV enhanced RLP provides a more efficient retransmission mechanism due to the sequencing of octets, rather than the sequencing of frames. This approach eliminates complex segmentation and reassembly issues, in the case that a retransmitted frame cannot fit into the payload available at the time of retransmission. • Location Update Protocol: This protocol is used to provide mobility management, which enables the Access Network to know the location of an AT at any instance. This service is critical in providing seamless packet transport service to the user through PDSN selection and handover. • Point-to-Point Protocol (PPP): This protocol is not part of the 1xEV specification, however, it is a key protocol that 3G technologies leverage to provide end-to-end connectivity between the PDSN and each AT. Therefore, it is worth mentioning its role in the 1xEV system. The PPP [...]... situations: (1) At a handoff boundary and within a single frequency band; (2) At a handoff boundary and between frequency bands (assuming the mobile station has multiband capability); (3) Within the same cell footprint and within a single frequency band; and (4) Within the same cell footprint and between frequency bands (assuming the mobile station has multiband capability) Handoffs from CDMA2000 1x-EV... address and same PPP connection, therefore allowing a seamless handoff Handoffs from CDMA2000 1x to cdmaOne systems CDMA2000 supports the handoff of voice and data calls and other services from a cdmaOne system to a CDMA2000 system, such that the handoffs could happen in the following different scenarios: (1) At a handoff boundary and within a single frequency band; (2) At a handoff boundary and between... (2) At a handoff boundary and between frequency bands (assuming the mobile station has multiband capability); (3) Within the same cell footprint and within a single frequency band; and (4) Within the same cell footprint and between frequency bands (assuming the mobile station has multiband capability) CDMA2000 supports the handoff of voice and data calls and other services from a CDMA2000 system to a... (2) (3) (4) (5) New radio interface (UTRAN) SMS, EMS, and MMS FDD and TDD at 3. 84 Mcps Handover CAMEL Phase 2 and 3 used for prepaid services and access charge in GSM and GPRS networks (6) EDGE (7) GSM-UMTS interworking (8) Call forwarding enhancement Release -4 (March 2001) (1) (2) (3) (4) (5) (6) (7) New TDD mode at 1.28 Mcps Data synchronization (SyncML) Evolution of UTRA to support IP SMS and EMS... system capacity compared to 2G and 2.5G cellular systems; and (4) High-speed packet data services ranging from 144 kbps in wide-area mobile environments to 2 Mbps in fixed or in-building environments The standardization of 3G systems was conducted in several regions through their respective standard organizations: • ETSI: European Telecommunications Standards Institute • T1: Standardization Committee-Telecommunications... nodes and Radio Network Controllers (RNCs) lowers backhaul costs by giving operators a choice of backhaul services, including frame relay, router networks, metropolitan Ethernet and wireless backhaul IP-based 1xEVDO networks take advantage of off-the-shelf IP equipment such as routers and servers, and use open standards for network management 1xEV-DO networks have the flexibility to support both user- and. .. Release 4 specifications both for FDD and TDD To better comprehend where the UMTS standard stands in the ITU IMT-2000 proposals, we provide Figure 3.18, where we have plotted all major ITU endorsed IMT-2000 candidate proposals which are later called 3G standards From among all the proposals or standards that were listed, we classified them into (1) TWO core technologies (TDMA and CDMA); (2) THREE systems. .. neither wide nor narrow; it is just a bandwidth Nevertheless, the new 3G WCDMA systems indeed have a wider bandwidth than the existing 2G CDMA systems (i.e 1.25 MHz bandwidth in IS-95), which is why it is called wideband It should be noted that the name of WCDMA is true in a relative sense, as there are commercially available CDMA systems operating over a 20 MHz bandwidth At this moment, it is significant... Handoffs from CDMA2000 1x-EV to cdmaOne/CDMA2000 1x systems The interoperability between 1x and 1xEV Networks are covered in the TIA Standard, IS-878 The following are examples of the handoff scenarios that are possible between 1xEV and 1x systems: • AT establishes a data session in 1xEV Radio Access Network (RAN) While the AT is dormant, it performs idle handoff from a 1xEV RAN to another 1xEV RAN • While... Node B and the control equipment for Node Bs is called Radio Network Controller (RNC) The spectrum allocation in Europe, Japan, and Korea for the FDD mode is 1920–1980 MHz for the uplink and 2110–2170 MHz for the downlink, with the bands 1980–2010 MHz and 2170–2200 MHz intended for the satellite part of the future systems The UTRA-TDD mode utilizes two frequency bands in Europe, the 1900–1920 MHz and . rate (kb/s) 38 .4 76.8 153.6 307.2 307.2 6 14. 4 6 14. 4 921.6 1228.8 1228.8 1 843 .2 245 7.6 Modem QPSK QPSK QPSK QPSK QPSK QPSK QPSK 8PSK QPSK 16QAM 8PSK 16QAM Encoded 10 24/ 10 24/ 10 24/ 10 24/ 2 048 / 10 24/ 2 048 /. Packets Bits 256 512 10 24 2 048 40 96 Rate(kbps) 9.6 19.2 38 .4 76.8 153.6 Code Rate 1 /4 1 /4 1 /4 1 /4 1/2 Symbols 10 24 2 048 40 96 8192 8192 Rate(ksps) 38 .4 76.8 153.6 307.2 307.2 Rate(ksps) 307.2 307.2 307.2 307.2 307.2 Figure. frequency band; (2) At a handoff boundary and between frequency bands (assuming the mobile station has multiband capability); (3) Within the same cell footprint and within a single frequency band; and