Wireless Mesh Networks

Wireless Mesh Networks

  • Nisar Ahmed Memon added an answer:
    4
    How to edit sip protocol header in real time?

    Hi Every one.

    we have asterisk based sip server and softphones.we created invite flooding attack on server.Now we want to change the sip header so that we can minimize invite flooding attack.

    Thanks

    Nisar Ahmed Memon

    Thanks sir. I have asterisk based server having softphone.Now sir what should I do ?

    please help?

    Thanks

  • Ali Alshammary added an answer:
    4
    Which tool is more compatible with the latest Transport layer schemes for wireless networks: NS-2 or NS-3?

    Hi everyone. I have just started working on Transport Layer Protocols for multi hop wireless networks. Please suggest to me if I should carry on my simulations in ns-2 or ns-3. And which is a better TCP compatible. Thank you so much.

    Ali Alshammary

    u can use ns-2 and ns-3 both work .

  • Senthil Kumar Sankareswaran asked a question:
    Open
    How can I draw an interlink network in cytoscape based on my special preferred proteins?

    I have 240 proteins which have been used in cytoscape GeneMANIA and then I used BiNGo to get 9 different networks. I merged our network image by Cytoscape merger but it appeared in separate group only.  

    I need that particular group interlink network. Can anyone suggest to me hoe to use different plugins or different tools.

  • Mehdi Amiri Nasab added an answer:
    3
    In wireless mesh networks, how do I decide the packet transmission with improved throughput under power constraint?

    In wireless mesh networks, how do I decide the packet transmission with improved throughput under power constraint?

    Mehdi Amiri Nasab

    you can use fazzy logic or automata  for select best decide  for your network ;

    for example fuzzy help you consider several parameters and select best decide base this parameters 

    or you can use automata for determinat state probability for next dicide 

    best regard ..

  • Albert Manfredi added an answer:
    1
    Apart from decoding complexity, is there any advantage in using fountain codes over random linear network coding on a line and non-mesh network ?

    assume that the decoding complexity is not an issue.

    Albert Manfredi

    I think the objectives may be different. The way I've thought of it, which may not always be the case, random linear network coding is a better way of transferring packets through a network, than by using traditional routing methods. With random linear coding, a single packet on a single link is used for multiple A to B connections at the same time. The conversations are then separated again close to the destination nodes. So this sort of coding maximizes the use of network bandwidth.

    Fountain codes are instead forward error correction codes which require very low overhead, compared with other FEC, and also low computational complexity. And they can even be implemented at the application layer, so different network client systems can use these without any impact on the infrastructure nodes.

    Or are you asking about the special case of using random linear network coding to accomplish forward error correction? In that case, if a given packet has been corrupted in transmission, the random linear network scheme will have to wait until a subsequent uncorrupted packet has been received, before it can correct the older packet. And the complexity issue then becomes the major issue, with fountain codes being simpler.

  • Yousef Darmani added an answer:
    13
    Which protocol gives better performance in terms of throughput and power efficiency for wireless mesh networks .whether UDP or TCP?

    which protocol gives better performance in terms of throughput and power efficiency for wireless mesh networks .whether UDP or TCP

    Yousef Darmani

    They are not the same and they don't perform as each other. Although I agree with Ar Reddy when he says UDP has higher throughput compare to TCP, but we must keep in mind their packet generator algorithms. Actually, TCP increases its window size when it gets ACK. Therefore, TCP sends more data toward its destination, if UDP's packet generation rate stays the same. Have a look at the old paper "MACAW A Media Access Protocol for Wireless LAN" for detailed information.

  • Tara Ramezani added an answer:
    2
    Does anyone have information bout low-latency in beacon scheduling for two-way transmission in Zigbee tree-based wsn?

    i'll need some algorithm for decrease latency for broadcast and converge cast

    Tara Ramezani

    tnx dear zeydin pal

  • Steven Baker added an answer:
    4
    How can we avoid 802.11b/g/n's interference when we use 802.15.4 systems?

    Currently, there is not any pure land on 2.4GHz ISM band because a lot of rf device use this band.
    My zigbee device use 2.4GHz band, but it always be broken by WIFI, do you have any idea to solve this issue?

    Steven Baker

    We did extensive testing with BT (1.0, 2.0, prior to adaptive frequency hopping) and followed a lot of the guidance from Matthew Shoemake's paper (link should be attached).   High-level:  Keep transceivers of the same frequency band at least 2-m apart.  Even if the 15.4 equipment is on a different channel than WiFi, there can be substantial interference and increase in the Packet Error Rate (PER) because the antenna bandwidth allows the entire band from 2.402 to 2.4835.  If one device is transmitting and very near the second that is trying to receive, the RF front end of the second may be saturated.

    As Mohammad pointed out, frequency hopping is a great solution to avoiding broad-band interference (that is what WiFi is from the .15.4 perspective).  I'll add "particularly if you have low data rates and can tolerate some latency waiting for a clear channel."  Ensure the middleware/driver can buffer data until a clear channel is found.  

    While the .15.4 system does not have data to transmit, occasionally listen on all the channels and keep track of where the least noise is an preferentially use those channels for transmission.  Before transmitting, listen to detect the noise level (you may not be able to decode the OFDM data from 802.11 for true CSMA/CA, but you can detect the noise).   If you search for 802.15.4 images, you should see some channel charts that show .15.4 channels (see link) and notice that for typical 802.11 configuration (using WiFi channels 1, 6, and 11) there is a gap between 802.11 channels 1 and 6, 6 and 11, and above 11 for .15.4 channels 15, 20, and 25,  respectively.   One can't guarantee these will be open, but they are more likely than others.  

    + 1 more attachment

  • Balaji Dhayabaran added an answer:
    11
    What kind of results have to be generated for SISO wireless Channel estimation using Least square estimation method?

    I am doing a simple channel estimation using Least squares algorithm in a SISO system using QAM modulation.

    I am new to this and I do not know what kind of results I have to plot.

    I wrote a Matlab code which estimates channel using Least squares algorithm and plots the average mean square error between original channel and estimated coefficients Versus the SNR.

    I am attaching the Matlab code and the plot for your reference. Kindly let me know what kind of results that I have to plot.

    Ready to give more details if you want.

    + 1 more attachment

    Balaji Dhayabaran

    Hi Nusrat,

    I already attached the matlab file in my first post. I dont have any problem in sharing ideas. If you want any other help I can help you out.

  • Ramy Atawia added an answer:
    3
    Any advice on Fast Fading?

    Could you please help me how i can generate an independent sample fast fading from Rayleigh distribution (NLOS) and the Rician distribution (LOS), I can the correlation in time due to mobility and also the correlation in frequency due to the multipath delay profile. i just need to get a statistically reasonable fading model.

    and some information about Jakes model.

    Thank you

    Ramy Atawia

    You can use the attached MATLAB which is supported by the ns-3 developers for simulating small scale fading in LTE according to the 3GPP documentations:https://www.nsnam.org/docs/release/3.21/models/html/lte-user.html

    + 1 more attachment

  • Abderrezak Rachedi added an answer:
    5
    For 40 nodes trust calculation experiment, is a 70% of selfish nodes environment possible for 40 nodes environment?

    please kindly provide solution for it. thankyou

    Abderrezak Rachedi

    Yes. You find the detail in these papers.

  • Dean Waters added an answer:
    4
    What is the application of a wireless mesh network?

    I want to have ideas on how to go doing a simulation in application of wireless mesh network using omnet++

    Dean Waters

    Mesh networks, as mesh sensor networks, are also being explored for use in agricultural settings to monitor sun, humidity, temperature, soil moisture, predator detection, etc.  

    A quick search popped up this:

    AGRO-SENSE: PRECISION AGRICULTURE USING SENSOR-BASED
    WIRELESS MESH NETWORKS
    Anurag D, Siuli Roy and Somprakash Bandyopadhyay

    http://www.123seminarsonly.com/Seminar-Reports/020/42275273-23514859-Agro-Sense-Precision-Agriculture-Using-Sensor-Based-Wireless-Mesh-Networks.pdf

  • Kennedy Chinedu Okafor added an answer:
    3
    How can I analyse throughput and transmission probability in an EDCA WLAN with each station having multiple traffic queues?

    I have 2 IEEE 802.11e network scenarios and i need to know the difference between them. One is a network where we assume stations transmit only one traffic type, say 4 stations and one transmits video, another transmits voice, another data, like that and the second scenario is where each station transmits all 3 or 4 traffic types. Question is:

    1. How is throughput analysed/affected in 2nd scenario considering each STA has multiple EDCAF.

    2. How do i analyse transmission probability on the channel?

    Kennedy Chinedu Okafor

    Using OPNET Modeller, configure an ESS or Adhoc WLAN and inject http traffic as well as configure the parameters. When you execute the simulation, you should be able to analyze the throughput metrics

  • Imad Jamil added an answer:
    4
    Which is better CSMA/CS vs TDMA ?

    Hello all, 

    Which access mechanism provides better performance (throughput, delay) TDMA or CSMA/CS ? and if you have a paper outline a comparison study of the two schemes...

    Many thanks 

    Imad Jamil

    Obviously you mean CSMA/CA.

    Actually, that depends on your needs. You need a simple, cheap, distributed, burden-less communication system, then CSMA/CA is the good choice. Using it you can got a fair network resources sharing between  contending nodes but you can't guarantee the optimal quality of service and fairness among nodes especially when the number of contending nodes increases. An example? IEEE 802.11 (Wi-Fi).

    In contrast, if you need a centralized, scheduled, managed, planned communication system and you can tolerate complex and expensive implementation, then TDMA is your choice. Using TDMA, you can always guarantee your target QoS on all nodes without unfairness because you're able to share optimally (or almost) the network resources among your nodes.

  • Hang Shen added an answer:
    3
    Hello all, I want to enhance AODV protocol by combining with hwmp protocol. Anyone familiar woth this?

    Please can any one help me to start this combination.

    Hang Shen

    NS-3 includes hwmp protocol, building upon which you can do some simulations to start your work. 

  • Harry Tunnell added an answer:
    4
    Can we transmit voice on zigbee device from one place to another?

    I want to implement at local area for secure communication of  military zone .

    Harry Tunnell

    There has been research to show that it is possible to use ZigBee to support voice communication. Here is one such study http://www.ijcta.com/documents/volumes/vol3issue1/ijcta2012030130.pdf

    A good source is the IEEE Xplore digital library, which has papers as recent as 2014 on the topic. You would have some work to do to determine how this would work in a military network, but voice using ZigBee is possible.

  • Maheswar Rajagopal added an answer:
    8
    What should be the proper parameters of wireless multimedia sensor network?

    If I would like to simulate wireless multimedia sensor network, what are the various parameters I need to to set? For instance, channel bandwidth, signal bandwidth, different protocols on various layers, data rate, tx power and many more.

    Maheswar Rajagopal

    In short, Include all QoS parameters

  • Kuldip Acharya added an answer:
    4
    Can you give me tcl script for Wireless mesh network in NS2 ?

    Dear all,

    I need running tcl scripts for wireless mesh network including gateway , routers For NS2 .

    please attach few,  if you have it.

    Thanks

    Kuldip Acharya

    Thanks Nidhi ~

  • Tuncay Ercan added an answer:
    5
    How to determine the weight of a link in wireless mesh network and the criteria behind ??

    How to determine the weight of a link in wireless mesh network and the criteria behind ??

    Tuncay Ercan

    first, you need to think about the minimum data rate requirements among different links. Data rate and probable congestion control in different nodes help to assign different weight values. Of course, you need to set up another admission control policy to evaluate your weighting links or at least being capable of dynamically change it

  • Osama Al Tameemi added an answer:
    3
    Can Toriodal distance measure enhance the simulation accuracy of random graphs and stochastic geometry?

    When performing analytical math on random graphs and point processes we usually tend to assume infinite sets, that is in order to enhance the tractability. However in practical systems and simulations we do not have an “infinite” space. A suggested workaround is to use Toroidal distances that convolves the flat simulation map similar to the famous “snakes” game.

    Can Toriodal distance measure enhance the simulation accuracy of random graphs?

    Is there any other method for counter-effect the edge problem ?


    Toroidal distance reference in the Appendix of:

    C. Bettstetter, "On the minimum node degree and connectivity of a wireless multihop network," in Proceedings of the 3rd ACM international symposium on Mobile ad hoc networking & computing, 2002, pp. 80-91.

    Osama Al Tameemi

    Edge effect, which refers to the points which lie at the border of ur finite deployment area, can bias the results especially as mentioned for interference, number of neighbors, and transmitted power. I would highly recommend using the  Toroidal distance to by-pass the edge effects.

  • Moshaddique Al Ameen added an answer:
    16
    What is the most energy efficient protocol for Wireless sensor networks?

    Energy is most important factor for Wireless sensor networks. A node is connected to the base station through a singlehop or a multihop. Here sleeping and wake-up schemes of different nodes are very important to achieve energy efficiency of the system. A protocol is used for communication between the nodes. So what is the most energy efficient protocol for Wireless sensor networks and how can we use priority and delay terms in designing protocols.

    Moshaddique Al Ameen

    The answer to your question is not straight forward. By nature MAC protocol depneds on the specific applications. You can refre to  "Energy Saving Mechanisms for MAC Protocols in Wireless Sensor Networks" http://dx.doi.org/10.1155/2010/163413 for some general overview.

  • Anuraag Misra added an answer:
    3
    Port "1" is inhomogeneously filled within the first 3 mesh cells but I cannot start solver. Can anyone explain why?

    Hi 

    When I was trying to simulate a design with coaxial line feeding in cst software I got the above error and the solver was aborted. The solution given for this error is please modify the mesh line distribution or the geometric model to meet this requirement.

    Please help me to overcome this problem.

    Thank you

    Anuraag Misra

    Please modify the mesh line distribution or the geometric model to meet the first 3 cell requirement.

  • Vinita Jindal added an answer:
    3
    Are there any real differences in Ad-hoc network applications?

    Can a member in ad-hoc network act as server and another act as a client of this server?

    Are there any restrictions about data forms that exchanged between these networks members? ie.. are these networks dedicated only for file transfer, or can be used for instant messages....?

    Vinita Jindal

    Yes any member in ad-hoc network act as server and another act as a client at different times.

    And moreover, there is no restrictions about data forms that will be exchanged between these networks members. they can send whatever they want. only things there has to be a path that should exist between source and destination.

  • Ali Hassan Sodhro added an answer:
    13
    Does anyone have experience with Network Metrics:Throughput, delay and jitter?

    As I have calculated Packet Loss Ratio, now want to calculate throughput, delay and jitter in Wireless Body Area Networks (WBAN), can anyone tell me how should I proceed further? Thanks in advance

    Ali Hassan Sodhro

    thanks nurul sarkar

  • Somil Saxena added an answer:
    9
    Is it possible to integrate an optical & and wireless network with NS-3 or NS-2?

    is it possible to integrate optical & and wireless network with NS-3 or NS-2?

    Somil Saxena

    what properties of PON, you wish to implement in backbone n/w?

  • mohammad azaharuddin Shaikh added an answer:
    23
    The minimum of energy required to communicate between two nodes (is there a closed form expression)?

    In wireless sensor networks, if we know the geometrical distribution process of nodes, can we calculate the expected energy cost to transmit a packet from point (A) to point (B) via other other nodes (routed via other nodes). What would be the least energy required?

    mohammad azaharuddin Shaikh

    in any network energy is transmitted from one node to another but according to the question,  it depends on the size of the packets and  there flag status of its header, means encoding style, which is to be transmitted as you know the geometric path you can calculate the total energy transmitted.

  • Nyembo Salama added an answer:
    13
    How can I create a fault tolerant network design without a single point of failure?

    What would be some of the approaches I could use in order to ensure a fault tolerant network design without a single point of failure, and which approach would be the best for an enterprise network?

    Nyembo Salama

    yes, the contribution "Muriel M Edard, Steven S. Lumetta, 'Network Reliability and Fault Tolerance" is highly helpful. 

  • Audrey Gendreau added an answer:
    21
    Does anyone have knowledge on the distance between two nodes in sensor networks?

    Apart from RSSI, what others parameters could be considered in calculating distance between two nodes. Would be thankful if anyone could recommend few high impact publication in this regard?

    Audrey Gendreau

    Here is a great article on this subject. 

  • Chandra Shekhar added an answer:
    3
    How does one find a neighborhood node in a wireless sensor network in Matlab?

    I have already created the wsn network and I'm finding the cluster head from that node and now I want to find the neighborhood nodes of cluster head. 

    Note: Are there any matlab functions to find that?

    Chandra Shekhar

    I hope, power level will help you.

  • Amal Algedir added an answer:
    5
    Does anyone have knowledge on Awk programs?

    I am trying to calculate delay in multiple hop wireless networks by using the AWK program from trace file but I have problem. It saves packet send time of last node as send time.

    Amal Algedir

    Thank you , I got code for m trace file

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