Effects of location awareness on concurrent transmissions for cognitive ad hoc networks overlayin(synopsis)

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  • 1. Effects of Location Awareness on Concurrent Transmissions for Cognitive Ad Hoc Networks Overlaying Infrastructure-Based Systems (Synopsis) 8
  • 2. ABSTRACT Through wideband spectrum sensing, cognitive radio (CR) can identify the opportunity of reusing the frequency spectrum of other wireless systems. To save time and energy of wideband spectrum, we investigate to what extent a CR system incorporating the location awareness capability can establish a scanning-free region where a peer-to-peer ad hoc network can overlay on an infrastructure-based network. Based on the carrier sense multiple access with collision avoidance (CSMA/CA) medium access control (MAC) protocol, the concurrent transmission probability of a peer-to-peer connection and an infrastructure-based connection is computed. It is shown that the frequency band of the legacy system can be reused up to 45 percent by the overlaying cognitive ad hoc network when CR users have the location information of the primary and secondary users. 8
  • 3. OBJECTIVE OF THE PROJECT EXISTING SYSTEM The existing things are consider the coexistence issue of the hybrid infrastructure-based and overlaying ad hoc networks has been addressed but in different scenarios. The idea of combining ad hoc link and infrastructure based link was proposed mainly to extend the coverage area of the infrastructure-based network. That is, the coverage area of ad hoc networks is not overlapped with that of the infrastructure-based network. In the present hybrid ad hoc/infrastructure-based network, which maintain the peer-to-peer cognitive radio (CR) users are located within the coverage area of the existing legacy wireless network. In this, to further improve the throughput of a wireless local area network (WLAN), it was suggested that an access point (AP) could dynamically switch between the infrastructure mode and the ad hoc mode. 8
  • 4. PROPOSED SYSTEM In this project, we are trying to provide the basic idea of utilizing location awareness to facilitate frequency sharing in a concurrent transmission manner. Specific achievements are summarized in the following: • We are going to show that a CR device having location information of other nodes can concurrently transmit a peer-topeer data in the presence of an infrastructure based connection in some region. We also dimension the concurrent transmission (or the scanning-free) region for CR users. Nevertheless, the wideband spectrum sensing procedure is still needed but is initiated only when the CR user is outside the concurrent transmission region. Therefore, the energy consumption of CR systems with location awareness capability can be reduced significantly. • Based on the CSMA/CA MAC protocol, a physical/MAC cross-layer analytical model is developed to compute the coexistence probability of a peer-to-peer connection and an infrastructurebased connection. Based on this analytical model, we find that concurrent transmission of the secondary CR users and the primary users in the legacy system can significantly enhance the total throughput over the pure legacy system. 8
  • 5. INTRODUCTION FEASIBILITY STUDY All projects are feasible given unlimited resources and infinite time. But the development of software is plagued by the scarcity of resources and difficult delivery rates. It is both necessary and prudent to evaluate the feasibility of a project at the earliest possible time. Three key considerations are involved in the feasibility analysis. Economic Feasibility: This procedure is to determine the benefits and savings that are expected from a candidate system and compare them with costs. If benefits outweigh costs, then the decision is made to design and implement the system. Otherwise, further justification or alterations in proposed system will have to be made if it is to have a chance of being approved. This is an ongoing effort that improves in accuracy at each phase of the system life cycle. Technical Feasibility: Technical feasibility centers on the existing computer system (hardware, software, etc.,) and to what extent it can support the proposed addition. If the budget is a serious constraint, then the project is judged not feasible. Operational Feasibility: People are inherently resistant to change, and computers have been known to facilitate change. It is understandable that the introduction 8
  • 6. of a candidate system requires special effort to educate, sell, and train the staff on new ways of conducting business. ALGORITHM & EXPLANATION The above figure is an illustrative example for the coexistence of two CR devices establishing a peer-topeer ad hoc link and a primary user connecting to the infrastructure-based network, where all the devices (MS1, MS2, and MS3) use the same spectrum simultaneously. The above figure illustrates a hybrid ad hoc/infrastructure-based network consisting of two CR devices (MS1 and MS2) and a primary user MS3. Assume that the secondary CR users MS1 and MS2 try to make a peer-to-peer connection, and the n primary user MS3 has been connected to the base station (BS) or AP of the legacy infrastructurebased system. In the figure, MS1, MS2, and MS3 are located at (r1, θ1), (r2, θ2), and (r3, θ3), respectively; the coverage area of the BS is πr2. All the primary and secondary users stay fixed or hardly move. We assume that the CR devices can perform the positioning technique to acquire their relative or absolute position by using GPS or detecting 8
  • 7. the signal strength from the BSs of legacy systems. The location information is broadcasted by using the geographical routing protocols. Although both the positioning and geographical routing may waste time and consume energy, they have no need to be processed for every data transmission. They are only performed when a new node joins or the node changes its position. Furthermore, with the help of upper layers, the location information is already stored in the device. Therefore, compared to the spectrum sensing at every transmission, we believe that the additional energy consumption and memory space due to the positioning and location update is relatively small. Based on the CSMA/CA MAC protocol, multiple users contend the channel, and only one mobile station within the coverage of the BS can establish an infrastructure-based communication link at any instant. To set up an extra peer to peer ad hoc connection in the same frequency band of the primary user, the secondary users not only require ensuring that the current infrastructure-based link quality cannot be degraded but also has to win the contentions between other feasible secondary users. Here, we consider that both primary and secondary users have identical transmit power. It is reasonable to assume that only one secondary user can establish a link after the contention at one instance due to the similar interference range. Denote SIRi and SIRa as the received signal-to-interference ratios (SIRs) of the infrastructure-based and ad hoc links, respectively. Then, we can define the coexistence (or concurrent transmission) probability (PCT) of the infrastructure-based link and CR-based ad hoc link in an overlapped area as follows: 8
  • 8. Where zi and za are the required SIR thresholds for the infrastructurebased and ad hoc links, respectively. To obtain the concurrent transmission region, it is crucial to calculate the coexistence probability of both the infrastructure and ad hoc links. If the link quality of the primary user cannot be guaranteed, CR devices have to sense and change to other frequency bands. We consider the two-ray ground reflection model in which there exist two paths between the transmitter and receiver. One is the line-ofsight, and the other is reflected from ground. Thus, the received power can be written as Where Pr and Pt are the received and transmitted power levels at a mobile station, respectively; hbs and hms represent the antenna heights of the BS and the mobile station, respectively; Gbs and Gms stand for the antenna gains of the BS and the mobile station, respectively; r is the distance between the transmitter and receiver; α is the path loss exponent; and 10ξ/10 is the logs normally distributed shadowing component. In our project, we are going to create an environment as a base station, some cognitive radios and some users. We are going to place some video frames in the base station for simulating the concept overlaying. Whenever, the user wants to retrieve a file with the carrier frequency through cognitive radios. For each GUI window as consider as a system. Also we will monitor the status of every cognitive radio. Software Requirements: 8
  • 9. # OPERATING SYSTEM : Windows XP # TECHNOLOGY : J2SDK1.4.1 And above Hardware Requirements: # PROCESSOR : Pentium III # CLOCK SPEED : 550 MHz # HARD DISK : 20GB # RAM : 128MB # CACHE MEMORY # OPERAING SYSEM : : 512KB Windows 2000 Professional # MONITOR : Color Monitor # KEYBOARD : 104Keys # MOUSE : 3Buttons MODULE DESCRIPTION 8
  • 10.  Base Station: Cognitive device must be able to detect very reliably whether it is far enough away from a primary base station and/or whether this primary base station is silent at a given point in time. For an individual detector this is very difficult due to different radio propagation paths and it may need to sense primary user signals buried deep under the noise floor.  Cognitive Radio: A cognitive radio transceiver is able to adapt to the dynamic radio environment and the network parameters to maximize the utilization of the limited radio resources while providing flexibility in wireless access. In this project, we show that a CR device having location information of other nodes can concurrently transmit a peer-to-peer data in the presence of an infrastructure based connection in some region. We also dimension the concurrent transmission (or the scanning-free) region for CR users. Note that a concurrent transmission region of a CR system is equivalent to a scanning-free region. A Cognitive Radio is a radio that can change its transmitter parameters based on interaction with the environment in which it operates.  Users: The identity of the users of radios who wish to join a network needs to be assured. In the CSMA/CA MAC protocol, multiple users contend the channel, and only one mobile station within the coverage of the BS can establish an infrastructure-based communication link at any instant. To set up an extra peer-to-peer ad hoc connection in the 8
  • 11. same frequency band of the primary user, the secondary users not only require ensuring that the current infrastructure-based link quality cannot be degraded but also has to win the contentions between other feasible secondary users. Here, we consider that both primary and secondary users have identical transmit power. It is reasonable to assume that only one secondary user can establish a link after the contention at one instance due to the similar interference range.  Multimedia frames: Wireless multimedia applications require significant bandwidth and often have to satisfy relatively tight delay constraints. Radio spectrum is a scarce resource. Limited available bandwidth is considered one of the major bottlenecks for high-quality multimedia wireless services. A reason for this is the fact that a major portion of the spectrum has already been allocated. On the other hand, actual measurements taken on the 0–6 GHz band and other spectrum occupancy measurements on licensed bands, such as TV bands, show the significant under utilization of the spectrum. Since Cognitive Radio can operate in different frequency bands which provides multimedia services. 8