gsm architecture simplified part 14

Number of Location Areas (LAs) has impact on BSC load. If there are many cells per area, the local page attempts will be quite heavy. If increasing the number of LAs, the paging load will go down. On the other hand: If high movability for mobiles, the load from location updates will increase. When finding the optimal point, also load in MSC must be looked into.

Section 8 Optimisation

Adding New Applications The following table presents the CP capacity impacts on an

average node

AUC (Authentication Center) -0.4% FNR (Flexible Numbering) -2.5% SCF (Service Control Function) -2.0% (Based on 10% IN calls) SSF (Service Switching Function) -10% (Based on 10% IN calls) PRA (Primary Rate Access 30B + D) -19% (Based on 10k BHCA PRA traffic)


Capacity Gains

IMEI Check on Location Update It is possible to switch off the IMEI check function for location

update, which increases the capacity with 2%.

Usage of Toll Ticket Output only those call data records that are needed, where

possible accounting should be used instead. For instance switching off the Land to Land call data record increases the capacity with 3.2%.


TMSI Reallocation Switching off the TMSI reallocation at location update, change of LAI, intra-

MSC function will result in 2% more capacity.

Authentication at Location Update Switching off authentication at location update, change of LAI, intra-MSC

will result in an increase of the capacity with 1%.


Selective IMEI Check It is advisable to use the selective IMEI check for all access types,

which results in a gain of capacity of 4%. To be able to decrease the system recovery time it is recommended to switch off IMEI checking for the access type location update.

Selective Authentication The usage of selective authentication for all access types is

strongly recommended from a capacity point of view. In case of the activation of selective authentication instead of authentication for each access, the increase of capacity is equal to 6.2%.


Conclusion

A better network and cell planning will result in some cases in more capacity, when less location updates and handovers are needed. Moreover the number of small nodes in a network may decrease the overall network capacity, since they may introduce more inter-MSC handovers, more new registrations and a higher amount of transit traffic compared to a network with several big nodes. Furthermore the split of GMSC and MSC allows a better maintainable network and more capacity in the separate entities, also the usage of different processors for each entity will be possible. Stand-alone HLR will also increase the total capacity in the network.


GPRS TCP/IP Strategies

Datagram: It is a technical term for a packet of data and composed of many components. The most basic is:

0100010101001010101001001011110101001010100101010100101010010101

0010101010100101010100101110000111110100100100010101000100000001

1110010010100100010101001010101001001011110101001010100101010100

1010100101010010101010100101010100101110001111101001001000101010

0010000000111100100101001000101010010101010010010111101010010101

0010101010010101001010100101010101001010101001011100001111101001

0010001010100010000000111100100101001000100

To: 129.23.88.12

From: 136.24.87.23

Header

Data


IP Datagram Components

Options (and padding)

Data

Destination Address Source Address

Time to Live Header Checksum Protocol Identification Flags Fragmentation Offset Version IHL Type of Service Total Length


Whats in a Datagram

Version: Version of IP (example: IPv4, IPv6) IP Header Length: The datagrams header size in 32 bit words. Type of Service: Indicates priority of the packet. This is determined

by the type of data in the packet. (QoS - Quality of Service) Total length: Size of the IP packet (in bytes). Identification: An integer number identifying the datagram.


Flags: A 3-bit field of which the low-order 2 bits control fragmentation. One bit specifies whether the packet can be fragmented; the second bit specifies whether the packet is the last fragment in a series of fragmented packets.

Fragmentation Offset: A sequence number for the bytes in this packet when reassembling.

Time-to-live: A counter that discards the datagram when it reaches a limited. This prevents the packet from looping endlessly on the network.

Protocol: Indicates which upper-layer protocol receives incoming packets after IP processing is complete.


Header Checksum: Helps ensure IP header integrity. Source Address: Specifies the sending node. Destination Address: Specifies the receiving node. Options: Allows IP to support various options, such as security. Data: Information payload.


TCP/IP is the Packet Data technology used by the Internet.

GPRS will also be using the TCP/IP standard.


Physical Link

Network Transport

TCP/

IP 7-

Laye

r Sta

ck

(OSI

Ref

eren

ce M

odel

)

TCP

Fiber cable, Microwave link

IP

Network Interface Card

WWW, e-mail, data services

Session Presentation Application


TCP Characteristics

Concerned only with the origin and destination on the network.

Adapts to congestion

Provides virtual connection


IP Addressing

For example: 150.215.17.9 (Octets 0-255) In binary form, it looks like: 10010110.11010111.00010001.00001001

IP number is like an address

136.20.2.3 136.20.2.2 136.20.2.1


An IP address consists of two parts Identifies the network Identifies the node or host

These two parts specifies the class where the node belongs..


Address Classes

There are 5 different address classes. The first byte of the first octet determines the class of the address.

Class A addresses start with 0. Class B addresses start with 10. Class C addresses start with 110. Class D addresses start with 1110. Class E addresses start with 1111


5 Classes of IP Address

1

125

31

63

15 15

Quantity of Domains (Networks) in each Class

Class A: 1-126

Class B: 128-191

Class C: 192-223

127: Reserved (loopback)


Finding an IPs Network Address When a node receives a packet, it needs to determine the Network

Address of the network where the destination node belongs. This is done by using the network subnet mask. Subtracting the subnet mask to an IP address results in the

identification of the network and node sections of an the IP address

10010110.11010111.00010001.00001001 150.215.017.009 - 11111111.11111111.00000000.00000000 255.255.000.000 10010110.11010111.00000000.00000000 150.215.000.000


Transmission Methods

Transmission is the supporting layer under TCP/IP.

Types of transmission Frame Relay ATM (Asynchronous Transfer Mode)


ATM

Asynchronous Transfer Mode - A high speed, low delay, multiplexing and switching technology that can support any type of traffic including voice, data, and video applications. ATM is ideally suited to applications that cannot tolerate time delay, as well as for transporting frame relay and IP traffic that are characterized as bursty.


Other Packet-Based Networks

X.25 --- A popular standard for packet-switching networks.

CLNP --- (Connection-Less Network Protocol) derived from IP.


gsm architecture simplified part 14

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