Shahabuddin, Rahaman, Rehman, Ahmad, and Khan
10
Sub‐system. Mobile Switching Center (MSC) and subscriber databases are parts of it.
MSC carries out the switching to connect the calling party with the called party. MSC
is connected with the Public Switched Telephone Network (PSTN), as shown in
Figure 1.2. Home Location Register (HLR) and Visitor Location Resister (VLR) are used
to determine the suggested identity of the subscriber for the MSC.
The GPRS system can be upgraded from a GSM system by introducing new components, such as serving GPRS support node (SGSN), and gateway GPRS support node
(GGSN), shown in Figure 1.2. For handling data, the packet control unit (PCU) is necessary
in the BTS. SGSN was designed to provide location and mobility management. Providing
IP access router functionality and connecting the GPRS network to the internet and
other IP are the two tasks of GGSN [1].
The data rate of GSM was further increased with the introduction of an enhanced
data rate for GSM evolution (EDGE) back in 1997. EDGE specified the use of 8PSK
modulation that allows almost three times as much throughput compared to GPRS. An
EDGE user could enjoy 80 kbps to 120 kbps of data rate.
1.4.3 Code Division Multiple Access
Code Division Multiple Access (CDMA)‐based digital cellular technology was first proposed by Qualcomm in 1989. In 1993, Qualcomm obtained the acceptance of telecommunication industry association (TIA) to embrace their proposal as an IS‐95 standard,
which was the alternative to IS‐54 TDMA, which was adopted earlier as the digital
evolution of AMPS. Unlike GSM, multiple users share the same frequency band at the
same time in IS‐95 CDMA. A unique orthogonal spreading code is assigned for each user
that helps to distinguish between different users on the receiver side. Spread signals showed
noticeable improvement to multipath fading and interference. The channel bandwidth of
IS‐95 CDMA is 1.25 MHz for transmitting 9.2 kbps of lower voice signal.
The technical advantages of IS‐95 CDMA were more capacity in per MHz of bandwidth, there was no limitation of built‐in limit of number of users, power consumption
was low so cell size of IS‐95 was larger, and soft handoff was introduced. Another interesting feature was the ability to detect the period of silence so that transmission of data
could be paused to save energy and increase overall efficiency. The above features gave
CDMA systems a huge commercial and user acceptance.
Supplemental Code Channel (SCH) was introduced in the version of IS‐95B. It is also
known as packet mode transmission for increased efficiency. For example, it supports
14.4 kbps, which is allowed to combine 7 SCH to maintain the peak data rate of 115.2 kbps.
1.4.4 Security in 2G
The 2G cellular network was developed due to an increasing need for improved transmission quality, capacity and coverage. The advancements in semiconductor technology
and microwave devices made digital transmission possible in mobile communications.
2G cellular networks incorporated data communications, unlike 1G, amongst other
kinds of digital services such as text messages, picture messages and MMS (multimedia
messages). With digitized services coming into play, data confidentiality and security
10
Sub‐system. Mobile Switching Center (MSC) and subscriber databases are parts of it.
MSC carries out the switching to connect the calling party with the called party. MSC
is connected with the Public Switched Telephone Network (PSTN), as shown in
Figure 1.2. Home Location Register (HLR) and Visitor Location Resister (VLR) are used
to determine the suggested identity of the subscriber for the MSC.
The GPRS system can be upgraded from a GSM system by introducing new components, such as serving GPRS support node (SGSN), and gateway GPRS support node
(GGSN), shown in Figure 1.2. For handling data, the packet control unit (PCU) is necessary
in the BTS. SGSN was designed to provide location and mobility management. Providing
IP access router functionality and connecting the GPRS network to the internet and
other IP are the two tasks of GGSN [1].
The data rate of GSM was further increased with the introduction of an enhanced
data rate for GSM evolution (EDGE) back in 1997. EDGE specified the use of 8PSK
modulation that allows almost three times as much throughput compared to GPRS. An
EDGE user could enjoy 80 kbps to 120 kbps of data rate.
1.4.3 Code Division Multiple Access
Code Division Multiple Access (CDMA)‐based digital cellular technology was first proposed by Qualcomm in 1989. In 1993, Qualcomm obtained the acceptance of telecommunication industry association (TIA) to embrace their proposal as an IS‐95 standard,
which was the alternative to IS‐54 TDMA, which was adopted earlier as the digital
evolution of AMPS. Unlike GSM, multiple users share the same frequency band at the
same time in IS‐95 CDMA. A unique orthogonal spreading code is assigned for each user
that helps to distinguish between different users on the receiver side. Spread signals showed
noticeable improvement to multipath fading and interference. The channel bandwidth of
IS‐95 CDMA is 1.25 MHz for transmitting 9.2 kbps of lower voice signal.
The technical advantages of IS‐95 CDMA were more capacity in per MHz of bandwidth, there was no limitation of built‐in limit of number of users, power consumption
was low so cell size of IS‐95 was larger, and soft handoff was introduced. Another interesting feature was the ability to detect the period of silence so that transmission of data
could be paused to save energy and increase overall efficiency. The above features gave
CDMA systems a huge commercial and user acceptance.
Supplemental Code Channel (SCH) was introduced in the version of IS‐95B. It is also
known as packet mode transmission for increased efficiency. For example, it supports
14.4 kbps, which is allowed to combine 7 SCH to maintain the peak data rate of 115.2 kbps.
1.4.4 Security in 2G
The 2G cellular network was developed due to an increasing need for improved transmission quality, capacity and coverage. The advancements in semiconductor technology
and microwave devices made digital transmission possible in mobile communications.
2G cellular networks incorporated data communications, unlike 1G, amongst other
kinds of digital services such as text messages, picture messages and MMS (multimedia
messages). With digitized services coming into play, data confidentiality and security