![current elapsed time since its initial transmission, so that candidate relays can record this stamp and update it as
the queuing time increases.
ALGORITHM: - CENTRALIZED AND DISTRIBUTED ALGORITHM
<param name=”filetext”>
</param>
Public IEnumreable<string> producewordblocks(string filetext)
{
int blocksize=250;
int startpos=0;
int len=0;
for(int i=0;i<filetext.Length;i++)
{
i = i + blocksize > filetext.Length – 1 ? filetext.Length – 1 : i + blocksize;
while(i >= startpos && filetext[i] != “ “)
{
i--;
}
if(i == startpos)
{
i = i + blocksize > (filetext.Length – 1) ? filetext.Length – 1 : i + blocksize;
len = (i – startpos) + 1;
}
else
{
len = i – startpos;
}
yield return filetext.Substring(startpos, len).Trim();
startpos = i;
}
}](https://image.slidesharecdn.com/exploitingcooperativerelayforhighperformancecommunicationsinmimoadhocnetworks-131007081819-phpapp01/85/Exploiting-cooperative-relay-for-high-performance-communications-in-mimo-ad-hoc-networks-6-320.jpg)
Exploiting cooperative relay for high performance communications in mimo ad hoc networks
- 1. Exploiting Cooperative Relay for High Performance Communications in MIMO Ad Hoc Networks ABSTRACT With the popularity of wireless devices and the increase of computing and storage resources, there are increasing interests in supporting mobile computing techniques. Particularly, ad hoc networks can potentially connect different wireless devices to enable more powerful wireless applications and mobile computing capabilities. To meet the ever increasing communication need, it is important to improve the network throughput while guaranteeing transmission reliability. Multiple-input multiple-output (MIMO) technology can provide significantly higher data rate in ad hoc networks where nodes are equipped with multi-antenna arrays. Although MIMO technique itself can support diversity transmission when channel condition degrades, the use of diversity transmission often compromises the multiplexing gain and is also not enough to deal with extremely weak channel. Instead, in this work, we exploit the use of cooperative relay transmission (which is often used in a single antenna environment to improve reliability) in a MIMO-based ad hoc network to cope with harsh channel condition. We design both centralized and distributed scheduling algorithms to support adaptive use of cooperative relay transmission when the direct transmission cannot be successfully performed. Our algorithm effectively exploits the cooperative multiplexing gain and cooperative diversity gain to achieve higher data rate and higher reliability under various channel conditions. Our scheduling scheme can efficiently invoke relay transmission without introducing significant signaling overhead as conventional relay schemes, and seamlessly integrate relay transmission with multiplexed MIMO transmission. We also design a MAC protocol to implement the distributed algorithm. Our performance results demonstrate that the use of cooperative relay in a MIMO framework could bring in a significantly throughput improvement in all the scenarios studied, with the variation of node density, link failure ratio, packet arrival rate and retransmission threshold. GLOBALSOFT TECHNOLOGIES IEEE PROJECTS & SOFTWARE DEVELOPMENTS IEEE FINAL YEAR PROJECTS|IEEE ENGINEERING PROJECTS|IEEE STUDENTS PROJECTS|IEEE BULK PROJECTS|BE/BTECH/ME/MTECH/MS/MCA PROJECTS|CSE/IT/ECE/EEE PROJECTS CELL: +91 98495 39085, +91 99662 35788, +91 98495 57908, +91 97014 40401 Visit: www.finalyearprojects.org Mail to:[email protected]
- 2. ARCHITECTURE Existing System In this Existing System, a various MAC schemes have been designed to exploit the intrinsic features of MIMO to improve the throughput and reliability; they may not be able to handle consecutive packet loss due to severe path loss, continuous deep fading or temporary topology changes and link breakages. Continuous packet retransmissions would lead to significantly throughout reduction. The severe transmission conditions pose a big threat to the growth of wireless applications. Although beamforming can help improve the transmission reliability, it compromises the potential multiplexing gain and hence reduces the transmission rate. In addition, when the channel condition is extremely weak or the distance between the transmitter and receiver is temporarily very long, even beaming-forming may not be able to ensure the transmission reliability for the direct link. Moreover, the design of MAC scheme to coordinate beamforming transmissions in a multi- hop network is very difficult. Disadvantage 1. Less throughput 2. Poor reliability 3. Path loss 4. Topology & link breakages. Proposed System In this Proposed System, an alternative to MIMO technique, recent efforts have been made to enable cooperative relay transmission to cope with channel degradation, with the assumption that network nodes have single antenna.
- 3. Our proposed strategy is named as Cooperative Relayed Spatial Multiplexing (CRSM). The main contributions of this paper are as follows. We mathematically model the problem and provide a centralized algorithm with proved approximation ratio to serve as the performance reference of the distributed algorithm. We practically divide the problem into two phases and provide simple but effective distributed scheduling algorithms that seamlessly incorporate the use of cooperative relay into MIMO transmission, which can guide the practical protocol design; We propose a simple relay scheme to formulate relay set and invoke relay transmission without extra signaling overhead; We design an efficient MAC protocol to support our distributed algorithm. Advantages 1. Multiplexing 2. Throughput 3. Fast Transmission Modules 1. COOPERATIVE RELAY a. Concurrently exploiting cooperative diversity and spatial multiplexing for transmission robustness and higher throughput. b. Obtaining relay packets without extra overhead c. Relay packet forwarding in conjunction with normal packet transmissions d. Relaxed synchronization requirements taking advantage of multi-stream reception capability of receivers. 2. PACKET SCHEDULING WITH RELAY TRANSMISSION a. Simple formulation of a candidate relay set for a packet b. Simple priority-based relay selection without extra signaling c. Support of load balancing and reduction of delay impact on relay nodes d. Receiver-facilitated reduction of redundant relay transmission 3. RELAY OPERATIONS a. Finding Candidate Relay Nodes b. Triggering of Relay Transmission
- 4. c. Constraining the Delay of Relay Transmission Modules Description 1. COOPERATIVE RELAY a. Concurrently exploiting cooperative diversity and spatial multiplexing for transmission robustness and higher throughput. In this module, Different from the literature work which exploits cooperative diversity in a single antenna case only to improve the transmission quality, in the proposed work, the relay transmissions coordinate with the transmissions in a neighborhood and take advantage of cooperative multiplexing to improve the overall network throughput. b. Obtaining relay packets without extra overhead In this module, with multi-packet reception capability brought by multiple antennas, a relay node can obtain the packet to be relayed through overhearing during its own data receiving when the sender attempts for initial direct transmission. c. Relay packet forwarding in conjunction with normal packet transmissions In this module, Instead of simply postponing the transmissions of packets with relay nodes as the direct sender, which is often the case in the conventional cooperative diversity study, a relay node can transmit a relay packet concurrently with its own packets, therefore avoid excessive delay for its own packets. d. Relaxed synchronization requirements taking advantage of multi-stream reception capability of receivers. In this module, the direct transmissions and relayed transmissions are performed independently, and a receiver node takes advantage of multiple antennas to decode transmissions from multiple streams without requiring synchronization at the symbol level between neighboring nodes as in conventional cooperative diversity schemes. 2. PACKET SCHEDULING WITH RELAY TRANSMISSION a. Simple formulation of a candidate relay set for a packet In this module, the nodes in a neighborhood collaboratively determine if a relay transmission is needed without sophisticated signaling. b. Simple priority-based relay selection without extra signaling
- 5. In this module, a candidate relay node schedules the transmissions of relay packets with its own packets based on their relevant priorities. As the relevant priority of relay packets to existing packets in different candidate relay nodes are different, our scheduling naturally selects the relay transmission among a group of candidate relay nodes. c. Support of load balancing and reduction of delay impact on relay nodes In this module, in our scheduling, a packet that experiences a longer delay as a result of repeated transmission failures of its source node has its priority increased, which may be higher than some packets at a candidate relay node (especially when the relay node has a lower load). It is therefore more likely for a relay node with lower traffic to forward the relay packets, which would balance the load of nodes in a neighborhood and the relay transmission would not significantly impact the transmission of an overloaded candidate relay node. In addition, with extra packets buffered to forward for other nodes, a candidate relay node could have a higher priority of being scheduled for transmission. d. Receiver-facilitated reduction of redundant relay transmission In this module, as a node self-determines if it can be a relay in a time slot based on the priority of the cached packet to avoid signaling overhead, there is a likelihood that multiple nodes may attempt to perform relay transmission. 3. RELAY OPERATIONS a. Finding Candidate Relay Nodes In this module, in a conventional relay strategy, a source often broadcasts a relay request explicitly, and waits for replies from the potential relay nodes. This process not only introduces extra signaling overhead, but also adds in delay for relay transmission. Instead, the process of finding candidate relays in our scheme is automatically performed at qualified nodes without involving the source and destination of a packet. b. Triggering of Relay Transmission In this module, instead of explicitly invoking relay transmission, in our scheme, triggering of relay transmission and selection of relay node is incorporated with normal packet scheduling. If a failed direct transmission is detected, i.e. a candidate relay receives packet but does not receive the successful reception acknowledgement for packet. c. Constraining the Delay of Relay Transmission In this module, a packet is dropped if its reception fails after has elapsed since its first direct transmission. To ensure that the source node and all candidate relay nodes have a consensus on the packet transmission status, a packet transmitted from its source node is attached with a timestamp indicating the
- 6. current elapsed time since its initial transmission, so that candidate relays can record this stamp and update it as the queuing time increases. ALGORITHM: - CENTRALIZED AND DISTRIBUTED ALGORITHM <param name=”filetext”> </param> Public IEnumreable<string> producewordblocks(string filetext) { int blocksize=250; int startpos=0; int len=0; for(int i=0;i<filetext.Length;i++) { i = i + blocksize > filetext.Length – 1 ? filetext.Length – 1 : i + blocksize; while(i >= startpos && filetext[i] != “ “) { i--; } if(i == startpos) { i = i + blocksize > (filetext.Length – 1) ? filetext.Length – 1 : i + blocksize; len = (i – startpos) + 1; } else { len = i – startpos; } yield return filetext.Substring(startpos, len).Trim(); startpos = i; } }
- 7. System Requirements: Hardware Requirements: • System : Pentium IV 2.4 GHz. • Hard Disk : 40 GB. • Floppy Drive : 1.44 Mb. • Monitor : 15 VGA Color. • Mouse : Logitech. • Ram : 512 Mb. Software Requirements: • Operating system : - Windows 7 Ultimate (32-bit) • Coding Language : C#.Net • Front End : Visual Studio 2010