CDMA One or IS-95

CDMA One is a second generation mobile telecommunications standard that uses CDMA, which is a multiple access scheme for digital radio, to send voice, data and signaling data between mobile telephones and cell sites.

CDMA, "code division multiple access" uses a digital modulation called spread spectrum which spreads the voice data over a very wide channel in pseudorandom fashion using a user or cell specific pseudorandom code. The receiver undoes the randomization to

collect the bits together and produce the original data. As the codes are pseudorandom and selected in such a way as to cause minimal interference to one another, multiple users can talk at the same time and multiple cells can share the same frequency. This causes an added signal noise forcing all users to use more power, which in exchange decreases cell range and battery life.

When CDMAone technology is chosen to implement in Neighborhood Area Networks of Smart Grid; Smart devices and Smart meters of NAN will be using CDMA locks, IC chips and linked to particular cellular carriers.

In USA service providers of CDMA include Verizon, Sprint operating in frequency band below 3000MHz. CDMA can provide up to 0.384 Mbit/s of Uplink and downlink capacity.

Below are advantages of using CDMAOne/IS-95

1) Capacity is IS-95's biggest asset; it can accommodate more users per MHz of bandwidth than any other technology.

2) Has no built-in limit to the number of concurrent users.

3) Uses precise clocks that do not limit the distance a tower can cover.

4) Consumes less power and covers large areas so cell size in IS-95 is larger.

5) Able to produce a reasonable call with lower signal (cell phone reception) levels.

6) CDMAOne uses soft handoff, reducing the likelihood of dropped calls.

7) IS-95's variable rate voice coders reduce the rate being transmitted when speaker is not talking, which allows the channel to be packed more efficiently.

8) Has a well-defined path to higher data rates.

Below are disadvantages of using CDMAOne/IS-95

1) Most technologies are patented and must be licensed from Qualcomm.

2) Breathing of base stations, where coverage area shrinks under load. As the number of subscribers using a particular site goes up, the range of that site goes down.

3) Because IS-95 towers interfere with each other, they are normally installed on much shorter towers. Because of this, IS-95 may not perform well in hilly terrain.

4) Even barring subsidy locks, CDMA phones are linked by ESN to a specific network, thus phones are typically not portable across providers.

3.2.4 3G Systems and UMTS (Universal Mobile Telecommunications System)

3G Systems were developed to provide global mobility with wide range of services which includes telephony, paging, messaging, Internet and broadband data. International Telecommunication Union (ITU) is the organization which defined the standard for third generation systems, referred to as International Mobile Telecommunications 2000

(IMT-2000). Third Generation Partnership Project (3GPP) which was formed performs technical specification work and technical development of 3G technology.

Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) mobile telecommunications technologies which is specified by 3GPP and is part of the global ITU IMT-2000 standard.

UMTS, using 3GPP, can support maximum data transfer rates of up to 45 Mbit/s (with HSPA+),[12] although at the moment users in deployed networks can expect a transfer rate of up to 384 kbit/s for R99 handsets, and 7.2 Mbit/s for HSDPA handsets in the downlink connection. This is still much greater than the 9.6 kbit/s of a single GSM error-corrected circuit switched data channel and 14.4 kbit/s for CDMAOne.

UMTS Architecture

A UMTS network consists of three interacting domains; Core Network (CN), UMTS Terrestrial Radio Access Network (UTRAN) and User Equipment (UE). The main function of the core network is to provide switching, routing and transit for user traffic.

Core network also contains the databases and network management functions.

The basic Core Network architecture for UMTS as seen in Figure 13 [18] is based on GSM network with GPRS. All equipment has to be modified for UMTS operation and services. The UTRAN provides the air interface access method for User Equipment. Base Station is referred as Node-B and control equipment for Node-B's is called Radio

Network Controller (RNC).

Figure 13: Structure of UMTS network

UMTS provides several different terrestrial air interfaces, called UMTS Terrestrial Radio Access (UTRA). [14] All air interface options are part of ITU's IMT-2000. In the currently most popular variant for cellular mobile telephones, W-CDMA (IMT Direct Spread) is used.

UMTS has enhanced security features compared to 2G protocols such as GSM, CDMA.

Below are security features implemented in UMTS, Entity authentication:

UMTS provides mutual authentication between the UMTS subscriber, represented by a smart card application known as the USIM (Universal Subscriber Identity Module), and the network in the following sense, 'Subscriber authentication': the serving network corroborates the identity of the subscriber and 'Network authentication': the subscriber corroborates that he is connected to a serving network that is authorized, by the subscribers home network, to provide him with services.

Signaling data integrity and origin authentication:

Integrity algorithm agreement: the mobile station and the serving network can securely negotiate the integrity algorithm that they use.

Integrity key agreement: the mobile and the network agree on an integrity key that they may use subsequently; this provides entity authentication.

User traffic confidentiality:

Ciphering algorithm agreement: the mobile and the station can securely negotiate ciphering algorithm that they use.

Cipher key agreement: the mobile and the station agree on a cipher key that they may use.

Confidentiality of user and signaling data: neither user data nor sensitive signaling data can be overheard on the radio access interface.

Network domain security:

The term ‘network domain security’ in the 3G covers security of the communication between network elements. In particular, the mobile station is not affected by network

domain security. The two communicating network elements may both be in the same network administrated by a mobile operator or they may belong to two different networks. [13]