Paper About RF/FSO Transmision Media Hybrid

Power consumption is an important design consideration for wireless sensor networks (WSNs).  Hybrid radio frequency/free space optical (RF/FSO) WSNs have the potential to reduce this power consumption substantially. 

This paper studies the performance of the RF/FSO WSN by comparing its network lifetime against the lifetime of a traditional RF-only WSN.

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RF/FSO Wireless Sensor Networks: A performance study Click Here

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Lifetime Comparison of RF only and hybrid RF or FSO Wireless Sensor Networks Clic Here

So, Information about this paper according my understanding is

1) Author Name : 

Sashigaran Sivathasan And Dominic C. O’Brien

2) Title Of Paper : 

RF/FSO Wireless Sensor Networks: A performance study

3) Source : 

IEEE Communications Society subject matter experts for publication in the IEEE "GLOBECOM" 2008 proceedings.

4) Summary Of Reported Research :

Sensing, communication and data processing contribute to the power consumption of a sensor node, with most power being consumed for communications.

Therefore, the lifetime of the network might be extended by employing more energy-efficient communications.

On WSN transmission media usually using RF transmission. But this way is not efficient in energy. This paper propose RF/FSO hybrid for better performance and life time. Important report from this paper are.  

First this paper explain about alocation of transmission type. (Figure 1). Node sensor which Line Of Sight (LOS) with base station using transmission FSO. But node sensor which not LOS using transmission RF. This figure explain about topology which will be simulated.

This topologi made by considering Block Factor. Block Factor means everythings that make communication between each sensor become not LOS.

From this topology, known two point. Non Reconfiguring Network and Reconfiguring Network. Non Reconfiguring Network means that e.g if node 2 ( Clusster Head ) dead, node 4,5,and node 6 considered dead. Reconfiguring Network means that node 4,5 and 6 capable to searching new Cluster Head if node 6 dead.

Simulation from this paper show that better lifetime get from Reconfiguring Network. Reconfiguring Network become not benefit if blocking factor is low. In this case network does not require communication multihop. Node can comunicated with base station directly.

Another result from simulation are 

Best RF/FSO network coverage is when the blocking factor is low. Blocking factor make node sensor force increasing coverage area. This make increasing energy consumption. To avoid that, important to increasing node density. High node density means position each other of nodes isn't too far. This will guarantee each node sensor communication become more successfully.

5) Strength Of Invention:

From Simulation aproach, this paper show that Hybrid RF/FSO at least twice more longer liftime than only RF. Hybrid RF/FSO is better alternative for designing WSN on future work.

6) Weakness :

RF, FSO and Hybrid RF/FSO must Line Of Sight. Network Reconfiguration still important if Blocking factor is high.

7) Limitation:

This paper just simulating performance of RF/FSO in one topology as shown as figure 1.

Analizing relationship between lifetime, blocking factor, coverage area and node density.
Analyzing comparison between Non Reconfiguration Network and Configuration Network.