TOPOLOGY
CONTROL IN MOBILE AD HOC NETWORKS WITH COOPERATIVE COMMUNICATIONS
ABSTRACT:
Cooperative
communication has received tremendous interest for wireless networks. Most existing
works on cooperative communications are focused on link-level physical layer
issues. Consequently, the impacts of cooperative communications on
network-level upper layer issues, such as topology control, routing and network
capacity, are largely ignored. In this article, we propose a Capacity-Optimized
Cooperative (COCO) topology control scheme to improve the network capacity in
MANETs by jointly considering both upper layer network capacity and physical
layer cooperative communications. Through simulations, we show that physical
layer cooperative communications have significant impacts on the network
capacity, and the proposed topology control scheme can substantially improve
the network capacity in MANETs with cooperative communications.
ARCHITECTURE:
EXISTING
SYSTEM:
Most existing works are focused on link-level
physical layer issues, such as outage probability and outage capacity.
Consequently, the impacts of cooperative communications on network-level upper
layer issues, such as topology control, routing and network capacity, are
largely ignored. Indeed, most of current works on wireless networks attempt to
create, adapt, and manage a network on a maze of point-to-point non-cooperative
wireless links. Such architectures can be seen as complex networks of simple
links.
DISADVANTAGES
OF EXISTING SYSTEM:
1. Low Network Capacity.
2. Communications are focused on physical layer
issues, such as decreasing outage probability and increasing outage capacity,
which are only link-wide metrics.
PROPOSED
SYSTEM:
We propose a Capacity-Optimized Cooperative (COCO)
topology control scheme to improve the network capacity in MANETs by jointly
considering both upper layer network capacity and physical layer cooperative
communications. Through simulations, we show that physical layer cooperative
communications have significant impacts on the network capacity, and the
proposed topology control scheme can substantially improve the network capacity
in MANETs with cooperative communications.
ADVANTAGES
OF PROPOSED SYSTEM:
1. Improve the network capacity in MANETs.
2. Dynamic traffic pattern and dynamic network
without a fixed infrastructure.
3. There are a source, a destination and several
relay nodes.
4. Cooperation can benefit not only the physical
layer, but the whole network in many different aspects.
MODULES:
1. Transmission in MANETs
2. Network Constraints
3. Relaying Strategies
4. Cooperative Communications
5. Multi-hop Transmission
MODULES
DESCRIPTION:
1.
Transmission in MANETs:
With physical layer cooperative communications,
there are three transmission manners in MANETs: direct transmissions, multi-hop
transmissions and cooperative transmissions. Direct transmissions and multi-hop
transmissions can be regarded as special types of cooperative transmissions. A direct
transmission utilizes no relays while a multi-hop transmission does not combine
signals at the destination. In Fig. 1c, the cooperative channel is a virtual
multiple-input single-output (MISO) channel, where spatially distributed nodes
are coordinated to form a virtual antenna to emulate multi antenna
transceivers.
2.
Network Constraints:
Two constraint conditions need to be taken into
consideration in the proposed COCO topology control scheme. One is network
connectivity, which is the basic requirement in topology control. The
end-to-end network connectivity is guaranteed via a hop-by-hop manner in the
objective function. Every node is in charge of the connections to all its
neighbors. If all the neighbor connections are guaranteed, the end-to-end
connectivity in the whole network can be preserved. The other aspect that
determines network capacity is the path length. An end-to-end transmission that
traverses more hops will import more data packets into the network. Although
path length is mainly determined by routing, COCO limits dividing a long link
into too many hops locally.
The limitation is two hops due to the fact that only
two-hop relaying is adopted.
3.
Relaying Strategies:
• Amplify-and-forward
•
Decode-and-forward
In amplify-and-forward, the relay nodes simply boost
the energy of the signal received from the sender and retransmit it to the
receiver. In decode-and forward, the relay nodes will perform physical-layer
decoding and then forward the decoding result to the destinations. If multiple
nodes are available for cooperation, their antennas can employ a space-time
code in transmitting the relay signals. It is shown that cooperation at the
physical layer can achieve full levels of diversity similar to a MIMO system,
and hence can reduce the interference and increase the connectivity of wireless
networks.
4.
Cooperative Communications:
Cooperative transmissions via a cooperative
diversity occupying two consecutive slots. The destination combines the two
signals from the source and the relay to decode the information. Cooperative
communications are due to the increased understanding of the benefits of
multiple antenna systems. Although multiple-input multiple-output (MIMO)
systems have been widely acknowledged, it is difficult for some wireless mobile
devices to support multiple antennas due to the size and cost constraints.
Recent studies show that cooperative communications allow single antenna
devices to work together to exploit the spatial diversity and reap the benefits
of MIMO systems such as resistance to fading, high throughput, low transmitted
power, and resilient networks.
5.
Multi-hop Transmission:
Multi-hop transmission can be illustrated using
two-hop transmission. When two-hop transmission is used, two time slots are
consumed. In the first slot, messages are transmitted from the source to the
relay, and the messages will be forwarded to the destination in the second
slot. The outage capacity of this two-hop transmission can be derived
considering the outage of each hop transmission.
SYSTEM
REQUIREMENTS:
HARDWARE
REQUIREMENTS:
•
System : Pentium IV 2.4 GHz.
•
Hard Disk :
40 GB.
•
Floppy Drive : 1.44 Mb.
•
Monitor : 15 VGA Colour.
•
Mouse :
Logitech.
•
Ram : 512 Mb.
SOFTWARE
REQUIREMENTS:
•
Operating
system : Windows XP.
•
Coding
Language
: C#.NET
•
Data
Base :
SQL Server 2005
REFERENCE:
QUANSHENG GUAN, F. RICHARD YU, OTTAWA SHENGMING JIANG, VICTOR C. M.
LEUNG, HAMID MEHRVAR, “TOPOLOGY CONTROL IN
MOBILE AD HOC NETWORKS WITH COOPERATIVE COMMUNICATIONS” IEEE
Wireless Communications , April 2012.