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- Impact of using CSS PHY and RTS/CTS Combined with Frame Concatenation in the IEEE 802.15.4 Non-beacon Enabled Mode PerformancePublication . Barroca, Norberto; Borges, Luís M.; Chatzimisios, Periklis; Velez, Fernando J.This paper studies the performance improvement of the IEEE 802.15.4 non-beacon-enabled mode originated by the inclusion of the Request-To-Send/Clear-To-Send (RTS/CTS) handshake mechanism resulting in frame concatenation. Under IEEE 802.15.4 employing RTS/CTS, the backoff procedure is not repeated for each data frame sent but only for each RTS/CTS set. The maximum throughput and minimum delay performance are mathematically derived for both the Chirp Spread Spectrum and Direct Sequence Spread Spectrum Physical layers for the 2.4 GHz band. Results show that the utilization of RTS/CTS significantly enhances the performance of IEEE 802.15.4 applied to healthcare in terms of bandwidth efficiency.
- Performance enhancement of IEEE 802.15.4 by employing RTS/CTS and frame concatenationPublication . Barroca, Norberto; Velez, Fernando J.; Borges, Luís M.; Chatzimisios, PeriklisIEEE 802.15.4 has been widely accepted as the de facto standard for wireless sensor networks (WSNs). However, as in their current solutions for medium access control (MAC) sub-layer protocols, channel efficiency has a margin for improvement, in this study, the authors evaluate the IEEE 802.15.4 MAC sub-layer performance by proposing to use the request-/clear-to-send (RTS/CTS) combined with frame concatenation and block acknowledgement (BACK) mechanism to optimise the channel use. The proposed solutions are studied in a distributed scenario with single-destination and single-rate frame aggregation. The throughput and delay performance is mathematically derived under channel environments without/with transmission errors for both the chirp spread spectrum and direct sequence spread spectrum physical layers for the 2.4 GHz Industrial, Scientific and Medical band. Simulation results successfully verify the authors’ proposed analytical model. For more than seven TX (aggregated frames) all the MAC sub-layer protocols employing RTS/CTS with frame concatenation (including sensor BACK MAC) allow for optimising channel use in WSNs, corresponding to 18–74% improvement in the maximum average throughput and minimum average delay, together with 3.3–14.1% decrease in energy consumption.
- Investigating Inclusiveness and Backward Compatibility of IEEE 802.11be Multi-link OperationPublication . Medda, Daniele; Chatzimisios, Periklis; Velez, Fernando J.; Iossifides, Athanasios; Wagen, Jean-FrédéricNowadays is not possible to avoid considering the coexistence and the fusion of different wireless technologies as completely separated entities. The ever-growing number of devices employing multi-RATs (Radio Access Technologies) that require continuous wireless connectivity is posing great challenges. Furthermore, the requirements in terms of both throughput and latency originated by the use cases, are pushing the current technologies to their limits, especially for indoor dense deployments that are usually covered by Wi-Fi. The IEEE 802.11 Working Group is currently tackling such challenges by working on a new amendment of the standard (namely 802.11be), which introduces, among other novelties, the multi-link operation (MLO). Through MLO, the target is to achieve simultaneous transmission over multiple bands to obtain massive bitrate up to 40 Gbps. The introduction of MLO poses challenges on the coexistence with older legacy devices in mixed networks. This contribution explores how the coexistence of legacy IEEE 802.11 devices and new IEEE 802.11be devices realizing the proposed multi-link feature can be improved by using an appropriate static band assignment policy. Another issue is how the overall network behaves when varying the number of devices and the legacy/new nodes ratio. Simulations for three different band allocation cases close to reality are developed. Performance results in terms of aggregated, average throughput and fairness are derived for different conditions.