3G Wireless Networks

WCDMA uses Quadrature Phase Shift Keying (QPSK) modulation in the uplink. This technique is depicted in Figure 6-5. The stream of spread and scrambled signals, such as the output shown in Figure 6-2, forms the complex-valued input stream of chips. ... [full story]

Once the different channels have been spread with appropriate channelization codes, they are combined, as shown in Figure 6-2, and then scrambled by a particular scrambling code. Two types of scrambling codes exist—long and short scrambling codes, with 224 possibilities ... [full story]

As mentioned, the channelization codes are used to separate multiple streams of data from a given user, whereas the scrambling codes are used to separate transmissions from different users. The channelization codes are known as Orthogonal Variable Spreading Factor (OVSF) ... [full story]

A physical channel is what carries the actual user data or control information over the air interface. A physical channel can be considered a combination of frequency, scrambling code, and channelization code, and in the uplink, as we shall describe ... [full story]

As mentioned, WCDMA uses a chip rate of 3.84 Mcps. As also mentioned, CDMA technology in general uses a spreading code to separate one user’s transmissions from those of another. In reality, however, there will be multiple simultaneous data streams ... [full story]

As described briefly in Chapter 4, “Third Generation (3G) Overview,” UMTS includes two of the air interface proposals submitted to the International Telecommunications Union (ITU) as proposed solutions to meet the requirements laid down for International Mobile Telephony 2000 (IMT-2000). ... [full story]

Universal Mobile Telecommunications Service (UMTS) represents an evolution of Global System for Mobile communications (GSM) to support thirdgeneration (3G) capabilities. In this chapter, we examine the details of the UMTS, including the air interface and network architecture. The initial focus ... [full story]

The specific migration path from any of the 2G platforms that an operator has deployed in a network to the 3G system involves the establishment of a migration path. The migration path involves numerous issues and technical challenges that will ... [full story]

The Wireless Application Protocol (WAP) is one of the many protocols being implemented into the wireless arena for the purpose of increasing mobility by enabling mobile users to surf the internet.WAP is being implemented by numerous mobile equipment vendors since ... [full story]

The deployment of CDMA2000 into a new network is different than integrating it into an existing network. To be more specific, the traffic volumes and usage patterns are undefined in an initial system, leading to a homogenous traffic distribution from ... [full story]

An operator can pursue several methods for estimating the amount of voice and packet traffic with regards to implementing CDMA2000 1xRTT. A more robust discussion with some examples is included in Chapter 13, “CDMA2000 System Design,” but the following concepts ... [full story]

CDMA2000, whether implemented as 1x only or a 1x/3x environment, needs to have the capability for handoffs and hangovers to exist in the system either between similar systems or legacy systems. Numerous decisions need to be made by the design ... [full story]

The frequency planning for CDMA2000-1x is the same as that done with IS-95. What is important is that the PN offset that is used for the existing sector, if IS-95 is deployed, be used for CDMA2000-1x. The PN offset value ... [full story]

The architecture that will be used for a CDMA2000 deployment is effectively the same as that used for an existing IS-95 system with the exception of the Packet Data Serving Node (PDSN) network, which is introduced with CDMA2000 systems. Additionally, ... [full story]

As implied previously, several deployment issues are associated with the introduction of CDMA2000-1x into a wireless system. Some of the obvious issues relate to the current spectrum usage that the operator has license control of. The spectrum usage considerations take ... [full story]

Phase one of CDMA2000, for the purposes of this discussion, is a 2.5G technology platform because it offers some but not all of the IMTS-2000 requirements that are envisioned for CDMA2000, like full mobility. For the purist at heart, IS-95B ... [full story]

Prior to the arrival of GPRS or EDGE, the need for higher speeds of data service was well recognized. At the time, GSM supported only data services of up to 9.6 Kbps—the maximum that could be provided on a single ... [full story]

 With the advent of EDGE, we find a number of new channel coding schemes in addition to the coding schemes that exist for GSM voice and GPRS. For packet data services in an EDGE network, we refer to Enhanced GPRS ... [full story]

As mentioned, EDGE uses the same 200-kHz channels and eight-timeslot structure as used for GSM and GPRS.With EDGE, however, 8-PSK modulation is introduced in addition to the 0.3 Gaussian Minimum Shift Keying (GMSK) used in GSM. 0.3 GMSK means ... [full story]

The network architecture for EDGE is basically the same as that for GPRS —largely the same network elements, the same interfaces, the same protocols, and the same procedures. We use the term “largely” because some minor differences exist in the ... [full story]

EDGE once stood for the term ‘Enhanced Data Rates for GSM Evolution.’ Not long after the technology was proposed, however, it was also suggested that it be used as part of the evolution of IS-136 TDMA networks. In fact, for ... [full story]

Among the nodes that need to be dimensioned for GPRS traffic are the BSC, the SGSN, and the GGSN. Generally, the capacity of a BSC is limited by the number of cells, the number of BTS sites (or interfaces to ... [full story]

The most straightforward way to determine the required GPRS air interface capacity is to estimate the amount of data traffic (in terms of bits/second) that a given cell will be required to handle in the busy hour. This can be ... [full story]

Dimensioning a GPRS network involves the dimensioning of a number of network elements (such as SGSNs and GGSNs) and a number of network interfaces (air interface, Gb, and Gn). Of each of the resources (nodes and interfaces) available in a ... [full story]

In GPRS, each PDU to or from the MS is passed individually and no permanent resource is established between the SGSN and MS. Thus, if a subscriber moves from the service area of one SGSN to that of another, it ... [full story]

The transfer of packet data is through the establishment of a Packet Data Protocol (PDP) context, which is effectively a data session. Normally, such a context is initiated by the MS, as would happen, for example, when a browser on ... [full story]

Combined GPRS/GSM Attach Figure 5-6 depicts a simple GPRS attach scenario that would apply to a Class-C MS. In the case of a Class-A or Class-B MS, the MS may want to simultaneously attach to the GSM network and the ... [full story]

GPRS functionality in an MS can be activated either when the MS itself is powered on, or perhaps when the browser is activated. Whatever the reason for the initiation of GPRS functionality within the MS, the MS must attach to ... [full story]

The following sections provide some straightforward examples of GPRS traffic. This allows for an understanding of the differences between GSM and GPRS, and later, the differences between GPRS and UMTS. Prior to describing these, we need to familiarize ourselves with ... [full story]

Figure 5-4 shows the signaling plane from MS to SGSN. At the lower layers, it is identical to the transmission plane. However, at the higher layers, we find the GPRS Mobility Management and Session Management (GMM/SM) protocol instead of the ... [full story]

Not only does the SGSN interface with a BSC for packet transfer to and from a given MS, direct logical interfaces are also used between an MS and an SGSN—for signaling (signaling plane) and for packet data transfer (transmission plane), ... [full story]

One can see a number of new network elements and interfaces. In particular, we find the Packet Control Unit (PCU), the Serving GPRS Support Node (SGSN), the Gateway GPRS Support Node (GGSN), and the Charging Gateway Function (CGF). The ... [full story]