Computer Communications (Networks)

Computer Communications (Networks)

  • Arijit Mukherjee added an answer:
    In Mobile Cloud Computing which is cost effective? Task executed by the nearby mobile device or task executed by Cloudlet or Cloud Server?

    We know in Mobile Cloud Computing (MCC), mobile's task are executed in Cloud or CloudLet. Suppose we have 3 mobile device named A, B, C and a Cloud Server named C_Server and a CloudLet named C_Let. Note all the 3 mobile device is connected with the same CloudLet and Cloud Server.

    Now let Mobile Device A needs a service. Now my question is that if the other device (B and C) can perform the task, which will be more cost effective? Offload the task to the C_Server, C_Let or Other mobile device (B and C). Is there any reference paper about this topics?

    Please let me know.

    Thanks in Advance. :)

    Arijit Mukherjee · Tata Consultancy Services Limited

    Look for keywords like LoadSense, Bartendr and RadioJockey. All authored by VIshnu Navda.

  • Matthias Vodel added an answer:
    What key management protocol is used here?

    Either it is symmetric or asymetric.

    Matthias Vodel · Technische Universität Chemnitz

    I confirm the answer: asymmetric encryption.

    Symmetric encryption is not really good scalable for large sized and changing network topologies. (n * (n-1) ) / 2 key pairs would be required.

  • Sai R N added an answer:
    What are the GUI tools for stimulating mobile adhoc network ?

    Suggest any GUI tool which will operate in the same lines as NS2 to stimulate moblie adhoc network 

    Sai R N · BITS Pilani

    I think NetSim is the best for this

  • Ali Mahdi Owayid added an answer:
    Is it true that Information Technology Process Automation (ITPA) will generate cost saving for IT Outsourcing Service Providers?

    Is it true that ITPA will generate cost saving for IT Outsourcing Service Providers? Some people commented that outsourced to countries with lower labor cost can deliver the IT services cheaper than rolling out ITPA – what is your opinion / experience on this?

    Ali Mahdi Owayid · Al Buraimi University College

    In addition to the answers above, i think the scale of organization( small, medium and large)  as well as the offered package of the organization to IT people, all these factors will determine the cost.  Ex. Most of the telecom companies choose outsourcing because their package is high for IT people.

  • Ankur Varshney added an answer:
    What kind of simulator could I possibly use for simulating wireless data center topologies?

    I need to analyse their performance in terms of job completion time and if possible  potential interference of wireless links.

    Ankur Varshney · University of Oxford

    I'm surprised why no one mentioned OMNET++.

    Give it a shot. Also, if you are interested, go through this paper. It will give you a nice overview about the most popular simulators available.

  • Mwangalalo wa-Mbali added an answer:
    Where can I get the source code for the implementation of AOMDV routing protocol in OMNET++?

    I would like to add some optimization functions in the AOMDV routing protocol, i want add the concept of cooperative packet caching, but to do that, i have to have the code for the implementation of AOMDV.

    Mwangalalo wa-Mbali · University of South Africa

    Thank you for your assistance

  • Padma Priya added an answer:
    Which is the best platform to install NS2 on Linux?
    I have to simulate DCCP and UDP on NS2 , for my presentation and showing the differences in throughput, delay, and jitter. I want to know that NS 2.35 standalone supports DCCP simulation, do I have to write any code for this simulation?
    I am new to NS2 n linux platform.
    Help is appreciated.
    Padma Priya · BMS College of Engineering

    Fedora 12, 14 and Ubuntu 12 and 14 both are good.

  • Sanjeetha Raja added an answer:
    In experiments to assess performance IPv4 , IPv6 addresses delay in IPv6 always a little more than IPv4 . Is the header of IPv6 size or not ?

    TCP Segment Delay

    Ethernet delay

    Sanjeetha Raja · M.S. Ramaiah Institute of Technology

    Apart from the above mentioned reasons, not all the networks support IPv6 addresses, in that case we have to either use concept of tunneling or dual stack approach to solve this problem, this adds more delay.

  • Maragatharajan Muthuswamy added an answer:
    I work on node classification using the markov process. Can anyone share code for this purpose, please?

    Hi, I am doing research on Ad Hoc networks. I want to analyze the behaviour of nodes. Therefore, I have planned to use the markov chain process to monitor the states of the nodes. If any one is doing research related to this please share your commands?

    Maragatharajan Muthuswamy · Kalasalingam University

    Hi all.... Instead of NS2 shall we use GloMoSim for such a simulation

  • Tassoult Nadia added an answer:
    How do I simulate a certificate revocation list (CRL) for VANET in ns2?

    I am trying to simulate an update for CRL in each node and RSU based on an information in the received message from other nodes in the range using ns2.35 and sumo 0.22.

    It is my first experience with the simulation tools and I have no idea how to start.

    I am confused of using Veins (OMNET, SUMO),or NS2 all those tools at the same time.

    I hope you can help me to define what the proposed tools and examples or strategies are to first simulate VANET and then implement a new approach for CRL distribution in VANET.

    However, if you think that another simulation tool may help me in this topic, I will be appreciative of any kind of help.

    Thanks for reading my message,

    Best regards.

    Tassoult Nadia · Université de Béjaïa

    Dear Abdulaziz M. Ghaleb

    Thank you for your response,

    Its a time-limited task,  i don't  want to change from NS2 to NS3 ;

    Thanks for the suggestion.

  • Muhammad Naveed added an answer:
    What is the optimum way to reduce the energy consumption in identifying cluster heads in wireless sensor networks?

    Considering the issues of unequal clustering size and equal clustering size.

    Muhammad Naveed · COMSATS Information Technology Center – CITC

    Energy efficiency is an important part of WSN. Arie and Lopez have already added valueable stuff. I just wanted to add always take spatial characteristics of WSN specailly asymetricness of Links which makes really un predictable to deal with when you are designing or implementing a protocol for centralized architecture of WSNs.

  • Eduard Babulak added an answer:
    What are the main distinguishing qualities of heterogeneous cellular networks?
    Femto and Pico eNBs are some of the commonly adopted HetNets. Their deployment in the traditional macro base stations is meant to increase capacity to proffer solution to increasing demands for data but these solutions in turn pose greater a problem of interference. If they are important to be adopted why is this so?
    Eduard Babulak · Maharishi University of Management

    Examples of heterogeneous elements include microcells, picocells, femtocells, and distributed antenna systems (remote radio heads), which are distinguished by their transmit powers/ coverage areas, physical size, backhaul, and propagation characteristics. This shift presents many opportunities for capacity improvement,
    and many new challenges to co-existence and network management.

    source: Heterogeneous Cellular Networks: From Theory to Practice in LTE-ADVANCED AND 4G WIRELESS COMMUNICATIONS: PART 2

  • Eduard Babulak added an answer:
    Are there any implementations for contributory group key schemes (e.g. TGDH)?

    It will be much better if the implementations are deployed on platforms such as Android or iOS.

    Eduard Babulak · Maharishi University of Management

    I would recommend reading a paper treating similar topic on: Invitation-Oriented TGDH: Key Management for Dynamic Groups in an Asynchronous Communication Model, presented at Parallel Processing Workshops (ICPPW), 2012 in Pittsburgh, PA, USA.

    In this paper the authors propose a suite of group key management protocols that allows a group of users to agree on a shared group key, which can be used to protect a shared file system stored remotely in the cloud. The protocols supports the refreshment of the group key at each group membership modification. Compared to other similar solutions, the key novelty of our protocols is that they require asynchronous communication channels, and only constant number of exponentiations on average, worst case logarithmic number of exponentiations even if membership modifications are controlled by arbitrary user. Moreover, the proposed scheme is fully decentralized, and its design is led by a practical, invitation-oriented approach.

  • Abdelhakim El Ouadih added an answer:
    What is the difference between AWR, HFSS, ADS, CST?
    Under what circumstances and parameters is each best to be used? General Concept information about Microwave design softwares?
    Abdelhakim El Ouadih · Cadi Ayyad University

    I advise you to have a look up to this file consisting in on a survey about EM simulators either  differential as FEM used by HFSS and FIT used by CST or integral simulators like  FEKO , momentum ADS using MoM.

  • Viengvilay Xayavongsa added an answer:
    How can big data intelligence be applied in smart grid technology?

    Recently, big data intelligence is getting popularity among the researchers for different applications. Can we use the same for smart grid technology?

    Viengvilay Xayavongsa · University of Arkansas - Fort Smith

    In my opinion, the efficiency and fluidity in the execution of data intelligence in terms of smart grid technology and big data is entirely dependent upon the scalability of the architecture within the smart grid itself. I believe, hardware-wise, is the final limiting factor in such systems, but software shouldn't be neglected. You can do only so much with software if you're approaching the absolute limits of the hardware itself.

    The most efficient and scalable "smart grid" technology I can think of right now are the neurons in your brain. From what I understand, your brain can contain up to 100 billion neuron nodes (+/- a few hundred million depending upon epigenetic, evolutionary, and environmental factors) and each node can create up to 10,000 different connections which totals up to a staggering 1 Quadrillion connections (10k x 100 Billion = 1 x 10^15), if all neural connections were saturated at the same time (all in 3 pounds of weight, and it's the most energy efficient supercomputer in the world running on only roughly 12 watts of energy). There is no artificial intelligent computer or grid in existence that can do that, ever (at least for now).

    Keep in mind, when I'm talking about neural connections, it's logical connections, not physical connections. The logical connection algorithms are unique to the neuron itself, which is why you can have two neurons with one physical connection, but you can have the capacity of 10,000 x 10,000 logical connections. You can form 100 million algorithmic logical connections with just two neurons if each neuron contains a capacitance of 10,000 logical connections and each logical connection performs a process and stores a unique memory pattern at the same time. Now THAT, is a smart grid, isn't it great?

    We must analyze and implement our smart grid technology the same way. In other words, let's just try to mimic human neural evolution and apply such concepts to our own artificially fabricated neural networks.  We must examine how we can recall data as fast as we store it (parallel data manipulation). Instead of promoting asynchronous throughput, why not support near flawless completely synchronous full duplex throughput, at least at the local grid level?

    Don't get me wrong, I do understand that the law of thermodynamics applies in terms of data speed in relation to semiconductors and the copper media in which the electrical signals travel through (the brain, unlike the computer, both the processing center and media in which and electrical signal travels are all made of the same material, neurons), but why not have each node that does almost the same thing as a neuron (basically like microscopic routers that can form hundreds of multi-point data connections  with other mini-routers and each logical connection forms a unique memory path and the unique forming of the memory path is also simultaneously a process as if the memory and processing activity were synonymous, not separate), but on a smaller and more energy efficient scale? These mini-routers should function as smoothly and as quickly as a high-end layer-3 switch.

    The only difference between the brain and an artificial machine is that the brain stores memory in the form of neural connections or pathways and this memory can be recalled forming the same neural algorithm. So in reality, the question is how can we build a smart grid that can "store" and "process" data in the form of artificial neural connections at the same time? (parallel function) This will help not only increase data storage capacity, but also increase processing capacity at the same time, of course everything I've state is theoretical, but it doesn't mean it isn't probable or even plausible.

    Allowing this concept to be implemented in current or future technology can pave a pathway for the simultaneous growth of both the grid and data. This allows the grid to evolve in proportion to the amount of data being stored. In essence, two neurons can form 10,000^2 connections (100 million total unique connections) while two transistors can only form 2^2 connections (8 total connections, which doesn't even account for separate memory (because the process itself doesn't hold a memory pattern at the same time, it produces an output, yes, but it doesn't save the output in its own relative logical network path) storage such as cache, RAM, and SSD/HDD). Modern machines are still in their infancy in terms of development, but we're slowly trucking along and correcting fallacies on the way; no rush. :-)

    This is the power of human imagination. Let's dream big shall we?

  • Akhilesh Akhade added an answer:
    What is the role of "Agent" in NetSim WSN simulation ?

    In NetSim WSN, I can see a icon in the GUI for "agent", and also several properties for this including mobility. What is the role of this agent ?

    Akhilesh Akhade · BITS Pilani, K K Birla Goa

    The agent is an abstraction for what ever is being sensed by the sensor. So it can fire, pressure, intruder ...etc. This agent will be sensed by the sensor and information will be transmitted to the sink node.

  • Khalid EL GHOLAMI added an answer:
    How do you send a beacon message in ns-2?

    How do you send a beacon message containing informations like position, and how do you extract this information and signal strength by a second node?

    Khalid EL GHOLAMI · Université Blaise Pascal - Clermont-Ferrand II

    Well In WSN, I guess you're using the wpan model to simulate the IEEE 802.15.4 standard. In this case, you should use the beacon enabled mode. There is some examples in the ns-2 tcl folder for different configurations. (e.g. for NS-2.35 allinone, you can find them here \ns-allinone-2.35\ns-2.35\tcl\ex\wpan)

    To send some data from the coordinator using the Beacon, you should fill the Beacon frame's payload.

    These are the comments from the wpan model's developer inside the function :

    " void Mac802_15_4::beaconTxHandler(bool forTX)"

    /* To populate the beacon payload field, <macBeaconPayloadLength> and <macBeaconPayload> should be set first, in that order (use primitive MLME_SET_request). */

    So right after these comments, the program copies the payload to the beacon for transmission. So you have to fill that field before transmitting the beacon.

    And here is a FAQ from the wpan model's developer (Can be useful to solve some common issues :

  • P. Prakasam added an answer:
    Is there any literature on location prediction in MANET using any swarm intelligence technique ?

    Is there any possibility, we can do any research in this field ?

    P. Prakasam · United Institute of Technology

    Please find the following link which will provide you a very good literature on the same.

  • Hossam Faheem added an answer:
    Is there anyone have worked at Oversim and Omnet++?
    I need to know how to start simulate at oversim and Omnet++
    Hossam Faheem · Ain Shams University

    Of course you have to read the user guide and follow up the necessary steps.

  • Mohanchur Sarkar added an answer:
    Is anybody familiar with VoIP Tech over IPv4/IPv6?
    I require help for my research work in the telecom / networking domain. My research is on assigning/distribution of address space for devices in the telecom domain...
    Mohanchur Sarkar · Indian Space Research Organization

    You can also see Open h323 project ... actually meant for video conferencing over the net it contains source code and lot of information in the domain you want to work. Three is also a vibrant user group where questions/answers in this topic is exchanged. You may get good information on VoIP.

  • Mohanchur Sarkar added an answer:
    How can I prove the improvement in energy consumption on any protocol in WSN?

    I would like to know what are the standards that should be used to compare between any protocol and improvement on this protocol in wireless sensor network.

    Mohanchur Sarkar · Indian Space Research Organization

    A easier way to prove the improvement in energy consumption is to show the increase in network life time. First simulate a known WSN scenario using ns2 and record the network lifetime. Then implement the protocol in ns2 and using the same scenario record the lifetime of the network i.e after how much time the nodes die. This when shown in a graph  will show the improvement in energy consumption. This is the way generally WSN protocols are shown to be superior in energy consumption over other WSN protocolsn in Journal papers. 

  • Mohanchur Sarkar added an answer:
    How can I use LEACH in NS-2 to implement a wireless sensor network?

    Wireless sensor network implementation.

    Mohanchur Sarkar · Indian Space Research Organization

    Leach support is already there is ns2. You need to write some TCL scripts to evaluate the performance of LEACH. For this you may have to go through the tutorial which is available with ns2 source. If you have done some modification to LEACH then you need to recompile ns2 before running the TCL scripts. You can also see the official website of the inventor of LEACH for more information and help.

  • Vincent Savaux added an answer:
    How can I find the cyclic correlation for a multi-carrier CDMA signal?

    Does anybody have a reference?

    Vincent Savaux · École Supérieure d'Electricité

    As for any signal, simply use the correlation of the signal. A general example is given here:

  • Jorge Werner added an answer:
    Could anyone present some information, survey, mechanisms about SDN (Software Defined Networking) applied to cloud computing?
    As elastic cloud architectures and dynamic resource allocation evolve and as mobile computer operating systems and virtual machines usage grows, the need has arisen for an additional layer of software-defined networking (SDN). Such a layer allows network operators to specify network services, without coupling these specifications with network interfaces. This enables entities to move between interfaces without changing identities or violating specifications. It can also simplify network operations, where global definitions per identity do not have to be matched to each and every interface location. Such a layer can also reset some of the complexity build-up in network elements by decoupling identity and flow-specific control logic from basic topology-based forwarding, bridging, and routing.

    Jorge Werner · Federal University of Santa Catarina


  • Jose Ramon Coz added an answer:
    On modelling Priority in M/M1/K queue system?

    How do you model multiple priorities in both preemtive and non-preemtive mode in a M/M/1/k queue? I would liek to know the queuing delay( head of line) and system delay in such a system.

    Jose Ramon Coz · Ingeniería de Sistemas para la Defensa de España

    Check this paper:

  • Stefano Pergoloni added an answer:
    What is the Li-fi infrastructure?

    Dear Friends,

    Li-Fi is next internet revolution, what is the infrastructure for this technology ? And when do you think this technology will be in actual service?

    Thanks in advance

    Stefano Pergoloni · Sapienza University of Rome

    Li-Fi is a term referring to Visible Light Communications(VLC) for ubiquitous high-speed wireless access in indoor environment where Light Emitting Diodes (LED) are, likely, already available, so it's possible to use the same infrastructure for communication and illumination purpose.
    For the market I think that in the next years we will see a growing number of VLC products for everyone's use, especially related to locations based applications that not require addition hardware if we use at receiver side, for instance, a smartphone with a CMOS camera[R].
    After that also high speed data transfer could be present in our everyday life, for truly Li-Fi applications. Even now there are some companies in this field like pureLifi ByteLight Lightbee.


  • Abdul Razaque added an answer:
    Can anyone help me in calculating performance metrics like delay,throughout,etc from ns-2 trace file for vanet routing protocols?

    I am not familiar with the scripts.

    Abdul Razaque · University of Bridgeport

    Hello Radhika,

    I have already generated graphs for  protocols of AODV,AOMDV,DSR and DSDV from the trace files and thanks.

    You can check your message please.

  • Peng Xu added an answer:
    Has anyone here worked on key management or key exchange in DTN using one simulator?

    I want to analyse the effect of key management in DTN . I would appreciate any useful idea especially using ONE simulator.

    Peng Xu · Chinese Academy of Sciences

    Hello Philip, I think that OMNET and NETA would be one of the available choices for your problem. 

  • A.V. Paneendra added an answer:
    How do I extract x,y,z signals as a single signal from an accelorometer gyroscope phone then decompose it into 3 signals?

    I need to extract f x,y,z signals, then combine them and re-extract them from the same signal without loss of data. 

    A.V. Paneendra · Association for Computing Machinery

    Please say how to extract x,y,z data from ADXL345 gyroscope?

About Computer Communications (Networks)

A computer network is a collection of computers and other hardware components interconnected by communication channels that allow sharing of resources and information.

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