Tae Ok Kim

Performance analysis of IEEE 802.15.4 non-beacon mode with the unslotted CSMA/CA

We provide a simple mathematical model of IEEE 802.15.4 unslotted CSMA/CA by busy cycle of M/G/l queueing system to obtain several performance measures. Our performance measures can be used for determining the optimal number of devices while supporting the required QoS constraints on the average packet delay and the packet loss probability, and also for calculating battery lifetime.

Performance analysis of IEEE 802.15.4 with non-beacon-enabled CSMA/CA in non-saturated condition

This paper proposes an analytical model of IEEE 802.15.4, which is a standard toward low complexity, low power consumption and low data rate wireless data connectivity. In this paper, we concentrate on the MAC performance of the IEEE 802.15.4 LR-WPAN in a star topology with unslotted CSMA/CA channel access mechanism under non-saturated modes. Our approach is to model stochastic behavior of one device as a discrete time Markov chain model. We believe that many WSN applications would benefit from our analytical model because many applications in WSN generate traffic in non-saturated mode. We obtain five performance measures: throughput, packet delay, number of backoff, energy consumption and packet loss probability. Our results are used to find optimal number of devices satisfying some QoS requirements.

Performance Analysis of IEEE 802.11 DCF and IEEE 802.11e EDCA in Non-saturation Condition

We analyze the MAC performance of the IEEE 802.11 DCF and 802.11e EDCA in non-saturation condition where device does not have packets to transmit sometimes. We assume that a flow is not generated while the previous flow is in service and the number of packets in a flow is geometrically distributed. In this paper, we take into account the feature of non-saturation condition in standards: possibility of transmission performed without preceding backoff procedure for the first packet arriving at the idle station. Our approach is to model a stochastic behavior of one station as a discrete time Markov chain. We obtain four performance measures: normalized channel throughput, average packet HoL (head of line) delay, expected time to complete transmission of a flow and packet loss probability. Our results can be used for admission control to find the optimal number of stations with some constraints on these measures.

Performance Analysis of a CSMA/CA Based MAC Protocol for Cognitive Radio Networks

We develop an analytical model to investigate the performance of a decentralized MAC protocol based on IEEE 802.11 DCF for cognitive radio networks with single spectrum band. Our analysis provides the throughput obtained by secondary users and the interference ratio perceived by primary users (SUs). The theoretical approach is verified by comparing its numerical results to simulation results. Numerical and simulation results depict the fundamental properties on the performance under various network parameters such as the number of SUs, the packet size of SUs and the minimum contention window size.

Analytical model of IEEE 802.15.4 non-beacon mode with download traffic by the piggyback method

We analyze the MAC performance of the IEEE 802.15.4 LRWPAN non-beacon mode with the piggyback method in nonsaturated condition. Our approach is to model a stochastic behavior of one device as a discrete time Markov chain. We propose an analytical model describing the download behavior of a device using piggyback method. We obtain the performance measures such as throughput, packet delay, energy consumption and packet loss probability of a device. Numerical results and simulation results show that the piggyback method which removes a backoff procedure in the backoff method can reduce the delay, loss probability and energy consumption compared with backoff method. Our results can be used to find the optimal number of devices with some constraints on packet delay and packet loss probability.

Performance Analysis of IEEE 802.15.4 Non-Beacon Mode Where Downlink Data Packets Are Transmitted by Piggyback Method

We analyze the MAC performance of the IEEE 802.15.4 non-beacon mode where both uplink and downlink traffic flows are executed simultaneously and downlink data packets are transmitted by piggyback method. To build the mathematical model of the stochastic behavior of a device with both uplink and downlink traffic flows, we combine the Markov chain model for the uplink transmission in T.O. Kim et al (2006) and one for the downlink transmission in T.O. Kim et al (2006), so that performance measures (e.g., uplink packet delay and downlink packet delay) are influenced each other. We obtain performance measures such as throughput, packet delay, packet loss probability and average energy consumption per one slot of a device. Numerical results and simulation results show that the piggyback method can reduce the packet delay, packet loss probability and energy consumption compared with those of backoff method.

Analytic Model of IEEE 802.15.4 with Download Traffic

This paper proposes an analytical model of IEEE 802.15.4, which is a standard toward low complexity, low power consumption and low data rate wireless data connectivity. In this paper, we concentrate on the MAC performance of the IEEE 802.15.4 LR-WPAN with non-beacon mode and non-saturated condition in a star topology. Our approach is to model stochastic behavior of one device as a discrete time Markov chain. We propose an analytical model considering only download traffic. We obtain five performance measures : throughput, packet delay, number of backoff, energy consumption and packet loss probability. Our results are used to find optimal number of devices with some constraints on these measures.

Performance analysis of IEEE 802.15.4 superframe structure with the inactive period

Abstract We analyze the performance of IEEE 802.15.4 MAC with superframe structure including the inactive period where each device is in non-saturated conditions. The superframe structure with a inactive period has the following two primary characterizations: (i) deferment of packet transmission until the following active period due to insufficient backoff slots for completing the packet transmission, (ii) high competition in the head part of the active period due to packets which were deferred from the previous active period and were arrived during the previous inactive period. These characterizations complicate the construction of a mathematical model of MAC with the superframe structure including a inactive period. In this paper, we construct a discrete time Markov chain (DTMC) model which takes into account these characterizations. By analyzing the DTMC, we obtain the main performance measures such as throughput, packet delay distribution, packet loss probability and energy consumptions of devices and the PAN coordinator. We demonstrate high accuracy of the proposed model by comparing the numerical results with simulation results. Finally, we optimize the lengths of the beacon interval and the active period to maximize the battery life of devices while satisfying quality-of-service (QoS) constraints on packet delay and packet loss probability.

Throughput analysis of split-channel MAC with p-persistent CSMA on the control channel and reservation scheme

We deal with the split-channel MAC where total bandwidth splits into one control channel for RTS/CTS dialogue and several data sub-channels for data packet transmission. We consider the with-reservation scheme which allows successful RTS/CTS dialogue to be stored in a virtual queue for future transmission when all of the data sub-channels are occupied. We obtain the throughput of the split-channel MAC, when the control channel adopts p-persistent CSMA and has with-reservation scheme, by modeling the stochastic behavior of the sum of the number of occupied data sub-channels and the number of successful RTS/CTS dialogues in the virtual queue, and the state of control channel as a two-dimensional discrete time Markov Chain (DTMC). The numerical results show that throughput of with-reservation scheme outperforms that of without-reservation scheme in particular when the data packet size is large. Also, from the numerical results, we obtain the optimal value of p to maximize throughput as the number of stations and average packet size vary.

Performance Analysis of IEEE 802.15.4 Non-beacon Mode with Both Uplink and Downlink Traffic in Non-saturated Condition

We analyze the MAC performance of the IEEE 802.15.4 LR-WPAN with non-beacon mode and non-saturated condition in a star topology. Our approach is to model stochastic behavior of one device with both uplink and downlink traffic as a discrete time Markov chain. First, we propose an analytical model of a device with only downlink traffic. Then, by combining the model of a device with only uplink traffic in and one with downlink traffic in this paper, we obtain the performance measures such as throughput, packet delay, energy consumption and packet loss probability of a device with both uplink and downlink traffic. Our results can be used to find the optimal number of devices so as to satisfy QoS (quality of service) on delay and loss probability.