QoS and channel-aware packet bundeling for capacity improvement in cellular networks

We study the problem of multiple packet bundling to improve spectral efficiency in cellular networks. The packet size of real-time data, such as VoIP, is often very small. However, the common use of time division multiplexing limits the number of VoIP users supported, because a packet has to wait until it receives a time slot, and if only one small VoIP packet is placed in a time slot, capacity is wasted. Packet bundling can alleviate such a problem by sharing a time slot among multiple users. A recent revision of cdma2000 1xEV-DO introduced the concept of the multi-user packet (MUP) in the downlink to overcome limitations on the number of time slots. However, the efficacy of packet bundling is not well understood, particularly in the presence of time varying channels. We propose a novel QoS and channel-aware packet bundling algorithm that takes advantage of adaptive modulation and coding. We show that optimal algorithms are NP-complete, recommend heuristic approaches, and use analytical performance modeling to show the gains in capacity that can be achieved from our packet bundling algorithms. We show that channel utilization can be significantly increased by slightly delaying some real-time packets within their QoS requirements while bundling those packets with like channel conditions. We validate our study through extensive OPNET simulations with a complete EV-DO implementation.Supported in part by U.S. National Science Foundation under grant no. 072971

Quality of service and channel-aware packet bundling for capacity improvement in cellular networks

Title from PDF of title page, viewed on May 26, 2011VitaIncludes bibliographical references (p. 76-84)Thesis (Ph.D.)--School of Computing and Engineering. University of Missouri--Kansas City, 2011We study the problem of multiple packet bundling to improve spectral efficiency in cellular networks. The packet size of real-time data, such as VoIP, is often very small. However, the common use of time division multiplexing limits the number of VoIP users supported, because a packet has to wait until it receives a time slot, and if only one small VoIP packet is placed in a time slot, capacity is wasted. Packet bundling can alleviate such a problem by sharing a time slot among multiple users. A recent revision of cdma2000 1xEV-DO introduced the concept of the multi-user packet (MUP) in the downlink to overcome limitations on the number of time slots. However, the efficacy of packet bundling is not well understood, particularly in the presence of time varying channels. We propose a novel QoS and channel-aware packet bundling algorithm that takes advantage of adaptive modulation and coding. We show that optimal algorithms are NP complete and recommend heuristic approaches. We also show that channel utilization can be significantly increased by slightly delaying some real-time packets within their QoS requirements while bundling those packets with like channel conditions. We validate our study through extensive OPNET simulations with a complete EV-DO implementation.Introduction -- Related work -- Background on wireless systems -- Multiple packet bundling -- Evaluation -- Conclusion

Demand-Based Wireless Network Design by Test Point Reduction

The problem of locating the minimum number of Base Stations (BSs) to provide sufficient signal coverage and data rate capacity is often formulated in manner that results in a mixed-integer NP-Hard (Non-deterministic Polynomial-time Hard) problem. Solving a large size NP-Hard problem is time-prohibitive because the search space always increases exponentially, in this case as a function of the number of BSs. This research presents a method to generate a set of Test Points (TPs) for BS locations, which always includes optimal solution(s). A sweep and merge algorithm then reduces the number of TPs, while maintaining the optimal solution. The coverage solution is computed by applying the minimum branching algorithm, which is similar to the branch and bound search. Data Rate demand is assigned to BSs in such a way to maximize the total network capacity. An algorithm based on Tabu Search to place additional BSs is developed to place additional BSs, in cases when the coverage solution can not meet the capacity requirement. Results show that the design algorithm efficiently searches the space and converges to the optimal solution in a computationally efficient manner. Using the demand nodes to represent traffic, network design with the TP reduction algorithm supports both voice and data users

Scheduling and handoff algorithms for 3g and 4G networks

Orientador: Shusaburo MotoyamaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: Este trabalho apresenta um estudo de desempenho dos enlaces diretos dos sistemas CDMA 1xEVDO RA, UMTS/HSDPA e WiMAX com ênfase em escalonadores de dados e nos novos critérios de aceitação de tráfego handoff horizontal e vertical para redes 3G e 4G. Estes novos critérios de aceitação de tráfego handoff horizontal e vertical levam em conta a ocupação do enlace, a ocupação do buffer, a potência do sinal recebido (RSS) e o tamanho do quantum (DRR) como parâmetros para a decisão do processo de handoff. Além disso, o estudo considera os escalonadores de dados Max C/I (Maximum Carrier Interference), DRR (Deficit Round Robin), PF (Proportional Fair), Pr (Prioritário) e a nova proposta Pr/PF (Priority Proportional Fair). Os critérios combinados aos escalonadores são avaliados pormeio de métricas de QoS em função da chegada de tráfego HTTP interno ou em handoff. Os resultados mostraram que conforme o critério e o escalonador adotados, podem assegurar a QoS dos sistemas móveis e ainda aceitar uma boa quantidade de tráfego handoff. O estudo é baseado em simulações computacionais através da ferramenta de software MatlabAbstract: This work presents a performance study of the forward links of CDMA 1xEV-DO RA, UMTS/HSDPA and WiMAX systems with emphasis on data schedulers and new criteria for horizontal and vertical handoff traffic acceptance in the 3G and 4G networks. These new criteria for horizontal and vertical handoff traffic acceptance take into account the link occupation, the buffer occupation, the received signal strength (RSS) and the size of quantum (DRR) as inputs for decision of handoff process. Moreover, the study considers the data schedulers Max C/I (Maximum Carrier Interference), DRR (Deficit Round Robin), PF (Proportional Fair), Pr (Priority) and the new proposal Pr/PF (Priority Proportional Fair). The criteria combined with the data schedulers are evaluated using QoS metrics in function of internal HTTP traffic or handoff traffic. The results showed that depending on the chosen criterion and scheduler, it is possible to assure the QoS of mobile systems and still accept a good amount of handoff traffic. The study is based on computer simulations through Matlab software toolDoutoradoTelecomunicações e TelemáticaDoutor em Engenharia Elétric

Multimedia in mobile networks: Streaming techniques, optimization and User Experience

1.UMTS overview and User Experience 2.Streaming Service & Streaming Platform 3.Quality of Service 4.Mpeg-4 5.Test Methodology & testing architecture 6.Conclusion

Cuantificación del estado del canal para la minimización de la potencia en sistemas con transmisores adaptativos

Los sistemas de comunicación operando en canales (móviles) inalámbricos degradan considerablemente sus prestaciones (tasa de transmisión, consumo de potencia o probabilidad de error) debido a los desvanecimientos que sufre el medio inalámbrico. Esta degradación puede mitigarse aprovechando el conocimiento del estado canal (CSI) en el receptor y en el transmisor. El CSI puede ser perfecto si el error de estimación del canal es despreciable o cuantificado si no se conoce el valor exacto del canal sino únicamente la categoría (región) a la que el canal pertenece. La presente disertación tiene como objetivo diseñar y utilizar de manera óptima la cuantificación del CSI a fin de minimizar la potencia transmitida satisfaciendo requisitos de calidad de servicio en términos tasa de transmisión y probabilidad de error. El escenario básico de aplicación consiste en sistemas de comunicaciones móviles con transmisores adaptativos en los que el receptor tiene conocimiento perfecto del canal mientras que el transmisor, típicamente a través de un canal de control de retorno, únicamente conoce una versión cuantificada del mismo. Las contribuciones de esta tesis cubren sistemas de comunicaciones de distinta complejidad, operando sobre distintos tipos de canales, para uno o múltiples usuarios. Simulaciones numéricas validarán las derivaciones analíticas y mostrarán el significativo ahorro energético cuando se implementan los esquemas propuestos. Las principales contribuciones de esta tesis pueden resumirse como sigue: (i) se derivan esquemas de cuantificación y de adaptación como la solución de un problema de minimización con ligaduras; (ii) se prueba que los esquemas de cuantificación de canal corresponden al menos a un óptimo local; (iii) se prueba que los esquemas de adaptación son globalmente óptimos; (iv) se demuestra que la complejidad computacional por cada realización del canal requerida para implementar los esquemas adaptativos es moderada o despreciable; (v) se demuestra que las necesidades de envío de información de control del receptor al transmisor son sorprendentemente pequeñas y (vi) se muestra que la potencia consumida por los esquemas adaptativos basados en CSI cuantificado es considerablemente menor que la potencia consumida por sistemas no adaptativos y a su vez que la pérdida de prestaciones de aquellos frente a los que hacen uso de CSI perfecto es pequeña. Estas contribuciones motivan la implantación práctica de esquemas similares a los propuestos en sistemas reales de comunicaciones que, con un incremento moderado de la complejidad, obtienen significativas mejoras en sus prestaciones. _____________________________________________Performance of wireless communication systems (quantified in terms of transmission rate, power e±ciency or error probability) degrades severely due to fading effects introduced by the shared air-interface. This degradation can be mitigated if channel state information (CSI) is available at the receiver and/or the transmitter side. Full CSI can be assumed when sufficient training allows for essentially perfect channel estimation, while quantized CSI can be used when only the class (cluster or region) that the channel belongs to is known. This dissertation aims at optimally designing and exploiting quantized CSI to minimize transmit-power under rate and error probability constraints. The setup comprises a wireless communication system with channel-adaptive modulation; where the receiver has available perfect CSI while the transmitter has only quantized CSI. In this context, innovative claims from a high-level vantage point pertain to novel schemes with variable complexity, under different channel types shared by single or multiple users. Simulated numerical tests corroborate the analytical claims and reveal that significant power savings result when implementing the proposed schemes. Specific contributions can be summarized as follows: (i) the quantization and adaptive transmission parameters can be obtained as the solution of a judiciously formulated constrained minimization problem; (ii) the channel quantization algorithms developed attain at least a local optimum of the objective function; (iii)the adaptive schemes reach the global optimum; (iv) the required computational complexity per channel realization for the adaptive schemes ranks from moderate to negligible; (v) the amount of feedback transmitters need from the receiver is stunningly small; and (vi) power consumed by adaptive schemes based on quantized CSI is significantly less than that required by non-adaptive alternatives, and closely approaches the power savings achieved by the benchmark perfect transmit-CSI design. These features encourage practical deployment of the proposed schemes that, with moderate computational overhead, offer a significant performance improvement