An Efficient Cross-Layer Aware Mapping of VoIP Calls In Wireless OFDMA System. Part I. Problem description and channel tracking
Аннотация
Purpose: This work addresses the problem of efficient broadcasting of resource allocations descriptors for VoIP traffic in mobile OFDMA-based wireless systems. Methods: We present the problem of mapping overhead and show that it can be substantially reduced by using semi-persistent allocations and by taking advantage of the periodicity of VoIP frames, generated by a multi-phase vocoder. To handle the impact of mobility on the characteristics of the wireless channel we utilize a cross-layer decision approach that tracks the channel quality and predicts the expected mobile user behavior such that the system may under-react to channel changes in some cases. Results: We explicitly show how the variability of the wireless channel can be tracked by using a Markovian model with a set of discrete states. By estimating both state- and transition probabilities of the multi-state Markovian model, we underline the foundations for a cross-layer decision algorithm that is able to overlook short transitions in channel states, without changing the modulation and/or the coding schemes. The main advantage of this approach is the ability to support multiple codecs, or a single codec with different operational modes, both result in different packet sizes and different periods. Practical relevance: The proposed channel tracking mechanism is simple enough to be implemented in the base station of any practical OFDMA-based system using the WiMAX or LTE technology.Опубликован
2015-04-01
Как цитировать
Бен-Шимол, И., & Китросер, И. (2015). An Efficient Cross-Layer Aware Mapping of VoIP Calls In Wireless OFDMA System. Part I. Problem description and channel tracking. Информационно-управляющие системы, (2), 90-97. https://doi.org/10.15217/issn1684-8853.2015.2.90
Выпуск
Раздел
Информационные каналы и среды