M Tech Dissertations

Permanent URI for this collectionhttp://ir.daiict.ac.in/handle/123456789/3

Browse

Has files: YesSubject: search.filters.subject.Cellular telephone systems

Search Results

Now showing 1 - 4 of 4
  • Thumbnail Image
    ItemOpen Access
    Modeling MANETs using queuing networks
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2007) Munjal, Aarti; Srivastava, Sanjay; Lenin, R. B.
    Mobile Ad Hoc Networks (MANETs) are becoming an attractive solution to the services that require flexible establishment, dynamic and low cost wireless connectivity. Since nodes are mobile, routing results vary significantly with the underlying mobility model. So, modeling (nodes as well as wireless links between them) plays a critical role in the performance analysis of MANETs. This work involves modeling MANETs in two ways. In the first model, nodes are modeled as static and wireless links between a pair of nodes are available or unavailable for exponential durations. When the link is available, nodes are connected and can have data transmission and data are lost if the link is not available as the nodes are not connected. Second model involves mobility being captured by making the servers go ON/OFF for exponential amount of time, and no departure takes place while server is on vacation. This way one does not lose packets but the queuing delay increases. In this work, these two queuing networks are proposed to study to performance measures of MANETs. Numerical results are derived using mathematical equations and then verified through simulation.
  • Thumbnail Image
    ItemOpen Access
    Novel local oscillator circuit for sub-harmonic mixer
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2005) Kishore, G. Pavan Krishna; Biswas, R. N.; Parikh, Chetan D.
    Direct Conversion RF transceiver is the enabling technique for the next generation cellular and personal communication devices striving for miniaturization, long life of battery and cost effectiveness. Existing techniques of Direct Conversion suffer from undesired carrier radiation from the receiver. This leads to distortion in the signal received by the users in the close proximity. The proposed transceiver design is an approach to address the discussed issue of carrier radiation. The existing systems use Sub Harmonic mixer to overcome this problem with a sinusoidal Local Oscillator (LO) running at half of the required carrier frequency. The W-CDMA systems which use QPSK modulation need eight phases of the LO, the generation of which consume large power due to the linear circuits used. The proposed design implements the octet phase LO using non-linear circuits. This leads to the significant improvement in terms of power consumption and area. The core work of the thesis involves designing and analysis of new circuit topology that uses CMOS inverter chain for generating the octet-phase trapezoidal LO, to drive the Sub Harmonic mixer. The improvements are possible through the reduced size of transistors used in inverter and its non-linear operation. Thorough analysis of the circuit is performed for both sinusoidal and trapezoidal LO. Competitive results are obtained from the analysis of the design in terms of conversion gain, carrier suppression and Input referred 3rd order Intercept Point (IIP3). The design is modified to make it robust for varying ambient temperatures using a junction diode. A two port model of the Sub Harmonic mixer is derived, which proves a non-sinusoidal LO can be used in place of sinusoidal.
  • Thumbnail Image
    ItemOpen Access
    Design and implementation of a framework for context aware mobile services
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2004) Jain, Nikhil; Srivastava, Sanjay
    Applications designed for mobile platforms are traditionally hampered by the limita¬tions of the client devices, in particular limited user interface and the change of user environment due to mobility. Incorporating location of the device, and more generally the whole context of the user and device in the computation has clear advantages. A framework for context aware mobile services (FCAMS) targeted for cellular data net¬work is proposed. We provide a detailed architecture of the framework. The design provides a generic way to add context to the mobile applications. An implementation of the framework along with an example service, ATM Finder is done. Functional analysis of the implementation is performed.
  • Thumbnail Image
    ItemOpen Access
    Design and implementation of a framework for context aware mobile services
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2004) Nitin, Saksena; Srivastava, Sanjay
    Applications designed for mobile platforms are traditionally hampered by the limita¬tions of the client devices, in particular limited user interface and the change of user environment due to mobility. Incorporating location of the device, and more generally the whole context of the user and device in the computation has clear advantages. A framework for context aware mobile services (FCAMS) targeted for cellular data net¬work is proposed. We provide a detailed architecture of the framework. The design provides a generic way to add context to the mobile applications. An implementation of the framework along with an example service, ATM Finder is done. Functional analysis of the implementation is performed.