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Resource Management in Wireless Networks

Description: A local call admission control (CAC) algorithm for third generation wireless networks was designed and implemented, which allows for the simulation of network throughput for different spreading factors and various mobility scenarios. A global CAC algorithm is also implemented and used as a benchmark since it is inherently optimized; it yields the best possible performance but has an intensive computational complexity. Optimized local CAC algorithm achieves similar performance as global CAC algorithm at a fraction of the computational cost. Design of a dynamic channel assignment algorithm for IEEE 802.11 wireless systems is also presented. Channels are assigned dynamically depending on the minimal interference generated by the neighboring access points on a reference access point. Analysis of dynamic channel assignment algorithm shows an improvement by a factor of 4 over the default settings of having all access points use the same channel, resulting significantly higher network throughput.
Date: August 2006
Creator: Arepally, Anurag
Partner: UNT Libraries

Impact of actual interference on capacity and call admission control in a CDMA network.

Description: An overwhelming number of models in the literature use average inter-cell interference for the calculation of capacity of a Code Division Multiple Access (CDMA) network. The advantage gained in terms of simplicity by using such models comes at the cost of rendering the exact location of a user within a cell irrelevant. We calculate the actual per-user interference and analyze the effect of user-distribution within a cell on the capacity of a CDMA network. We show that even though the capacity obtained using average interference is a good approximation to the capacity calculated using actual interference for a uniform user distribution, the deviation can be tremendously large for non-uniform user distributions. Call admission control (CAC) algorithms are responsible for efficient management of a network's resources while guaranteeing the quality of service and grade of service, i.e., accepting the maximum number of calls without affecting the quality of service of calls already present in the network. We design and implement global and local CAC algorithms, and through simulations compare their network throughput and blocking probabilities for varying mobility scenarios. We show that even though our global CAC is better at resource management, the lack of substantial gain in network throughput and exponential increase in complexity makes our optimized local CAC algorithm a much better choice for a given traffic distribution profile.
Date: May 2004
Creator: Parvez, Asad
Partner: UNT Libraries

The impact of leadership capacity and style on professional learning communities in schools.

Description: Leadership capacity may be enhanced when school staff members work together as a professional learning community (PLC). Leadership style may impact how well a school staff work as a professional learning community. The purpose of this study was to assess the relationship between principal leadership style and the level of PLC on 18 campuses across the US that were working on becoming PLCs. Staff members answered questions from two surveys which measured the level of leadership capacity, leadership style of the principal, and level of professional learning community within the schools. Questions regarding leadership capacity and leadership style were taken from the Leadership Capacity School Survey. Questions designed to measure the level of PLC on a campus were taken from the Professional Learning Community Assessment. The product-moment correlation coefficient or Pearson r was calculated between the answers from the questions from both surveys. The results indicated that when a capacity building principal is working with staff members to create a PLC, a higher level of PLC development is evidenced. When principals used collaboration with their staff, their schools operated at a lower level as a PLC. These results encourage principals to consider building capacity among their staff members if they want to create professional learning communities on their campus.
Date: December 2008
Creator: Scoggins, Kimberly Travis
Partner: UNT Libraries

Capacity and Throughput Optimization in Multi-cell 3G WCDMA Networks

Description: User modeling enables in the computation of the traffic density in a cellular network, which can be used to optimize the placement of base stations and radio network controllers as well as to analyze the performance of resource management algorithms towards meeting the final goal: the calculation and maximization of network capacity and throughput for different data rate services. An analytical model is presented for approximating the user distributions in multi-cell third generation wideband code division multiple access (WCDMA) networks using 2-dimensional Gaussian distributions by determining the means and the standard deviations of the distributions for every cell. This model allows for the calculation of the inter-cell interference and the reverse-link capacity of the network. An analytical model for optimizing capacity in multi-cell WCDMA networks is presented. Capacity is optimized for different spreading factors and for perfect and imperfect power control. Numerical results show that the SIR threshold for the received signals is decreased by 0.5 to 1.5 dB due to the imperfect power control. The results also show that the determined parameters of the 2-dimensional Gaussian model match well with traditional methods for modeling user distribution. A call admission control algorithm is designed that maximizes the throughput in multi-cell WCDMA networks. Numerical results are presented for different spreading factors and for several mobility scenarios. Our methods of optimizing capacity and throughput are computationally efficient, accurate, and can be implemented in large WCDMA networks.
Date: December 2005
Creator: Nguyen, Son
Partner: UNT Libraries

Electric Power Monthly: August 1995

Description: Monthly publication containing statistical data at state, census division, and U.S. levels regarding "net generation by energy source; consumption, stocks, quantity quality and cost of fossil fuels; and capability of new generating units by company and plant" (p. iii).
Date: August 16, 1995
Creator: United States. Energy Information Administration.
Partner: UNT Libraries Government Documents Department