1. What is EDGE?
Enhanced data rate for global evolution (EDGE) is:
A high-speed mobile data standard
Intended to enable second-generation global system for mobile
communication (GSM)
Time division multiple access (TDMA) networks to transmit data at
up to 384 kilobits per second (Kbps).
EDGE manages to increase data speeds using the same 200 kHz
GSM radio carriers by means of a different type of modulation.
2. What is an EDGE in a network?
An edge device is a device which provides an entry point into
service provider core networks.
Examples include routers, routing switches, integrated access
devices (IADs), multiplexers, and a variety of metropolitan
area network(MAN) and wide area network (WAN) access
devices.
4. The EDGE Network
SGSN: GPRS Support Node - this forms a gateway to the services within the
network.
GGSN: Gateway GPRS Support Node which forms the gateway to the
outside world.
PCU: Packet Control Unit which differentiates whether data is to be routed to
the packet switched or circuit switched networks.
5. SGSN
(Serving GPRS Support Node)
It provides a variety of services to the mobiles:
Packet routing and transfer
Authentication
Attach/detach
There is a location register within the SGSN and this stores location
information.
It also stores the user profiles for all the GPRS users registered with the
particular SGSN.
6. GGSN
(Gateway GPRS Support Node)
Organizes the inter-working between the EDGE network and external packet
switched networks to which the mobiles may be connected.
Considered to be a combination of a gateway, router and firewall as it hides the
internal network to the outside.
Operation: When the GGSN receives data addressed to a specific user, it
checks if the user is active, then forwarding the data. In the opposite direction,
packet data from the mobile is routed to the right destination network by the
GGSN.
7. PCU
(Packet Control Unit)
It is a hardware router that is added to the BSC
PCU itself may be a separate physical entity
It is incorporated into the base station controller, BSC, thereby saving
additional hardware costs.
8. VOIP AND ITS CHALLENGES
What is VOIP?
Voice carried by IP (Internet Protocol)
Voice sent in same manner as e-mails and other internet data
RTP header added to IP packet to make a VOIP packet
At transmitter data (voice) is compressed, converted to digital and packets
carrying distinct serial numbers
At receiver data is decompressed, converted back to analogue and packets
rearranged
10. SYSTEM CAPACITY:
Provision of sufficient bandwidth is the first crucial step towards
achieving a desirable QOS (quality of service)
The challenge is that the available bandwidth is a limited resource
A bandwidth imbalance may exist in the uplink and the downlink
due to symmetrical bandwidth
11. PACKET LOST
Voice treated as normal data in network
Packets may be dropped when network is congested
Re-transmission of packets is not a solution for voice data as they
contain 40 to 80 ms of speech information
Packet Loss Concealment (PLC) or Packet Loss Recovery (PLR
) algorithms compensate lost data
Identification and classification of VoIP packets can reduce
packet loss
12. DELAY/NETWORK LATENCY
When voice packets take a longer time than expected to arrive at
their destinations
Packets arrive late or never at all
There are fixed delays and variable delays(jitter)
Causes of delay
Codec
Queuing
Wait for packet being transmitted
Serialization
Jitter buffer
13. JITTER
A variable delay caused mainly by queuing, contention and
serialization along the network
Occurs in slow and heavy congested links
queuing based on class, reservation of bandwidth and faster links
can reduce jitter
Types of jitter
Type A: this type is classified as a constant jitter.
Type B: this type is termed as the transient jitter.
Type C: this is the jitter composed of short term delay variations.
14. 5.ECHO
Repetition of voice
Echo time interval varies with the causes of the echo
PSTN have less echo due to less delays compared to VoIP
Two types of echoes:
Talkers echo
Listeners echo
Echo cancellers are used to remove echoes
15. 6.SECURITY:
Many consumer VoIP solutions do not support encryption yet
This makes it easy to eavesdrop
Compression used to prevent eavesdropping
This doesn’t completely prevent eavesdropping
Encryption and cryptography are the best solutions against eavesdropping
16. CONCLUSION
VOIP is a cheaper alternative of PSTN
Uses internet as the backbone network
Although cheap, VoIP has a very low Quality of service
Performance of VoIP is hindered by factors like delay and packet
loss
Internet is not perfectly designed for carrying voice
VoIP can only be used in conjunction with the PSTN and not to
replace it yet
17. Handover and Roaming:-
Roaming :-
The ability for a cellular customer to automatically make and
receive voice calls, send and receive data, or access other
services when traveling outside the geographical coverage area of
the home network, by means of using a visited network.
18. HAND OVER
The term handover is used when a subscriber wonders in the cells in a
local cellular system in a cellular technology. When a person travels
among different cellular systems in many countries or the city then it
is called that he is roaming.
The Smart mobile phone will change its sending and receiving channels
during the handover, but this occurs too rapidly for users to the notice.
