Performance analysis of a multiple access protocol for voice and data support in broadband wireless LANs (original) (raw)

Performance Analysis of Multiple Access Protocol

1986

Wireless Local Area Networks (WLANs) is one of the most promising access technologies for the upcoming fourth-generation wireless communication systems. In the last few years, several research efforts have been devoted to investigate possible multiple access schemes capable of supporting real-time traffic as well as best-effort data transmissions. In particular, the use of suitable transmission schemes allows not only to achieve higher data-rates, but also to perform resource allocation in order to guarantee specific service requirements. In this paper we propose a medium access control (MAC) scheme for a WLAN supporting realtime (voice) and best-effort (data) services, based on Orthogonal Frequency Division Multiplexing (OFDM) technique. A suitable analytical approach is proposed in order to derive the performance of the proposed MAC scheme. In particular, it is shown in the paper that a high overall network capacity in terms of simultaneously active users is achieved by effectively exploiting the multiuser capabilities offered by OFDM, together with a proper service differentiation.

A new MAC protocol for broadband wireless communications and its performance evaluation

Telecommunication Systems, 2013

This paper presents a new Time Division Multiple Access/Frequency Division Duplexing (TDMA/FDD) based Medium Access Control (MAC) protocol for broadband wireless networks, supporting Quality of Service (QoS) for real-time multimedia applications. It also gives the Call Blocking Probability (CBP), packet end-to-end delay and utilization analysis of different service classes, as they are most essential performance criterions in broadband wireless network assessment. The Connection Admission Control (CAC) mechanism in the proposed MAC efficiently organizes the bandwidth allocation for different service classes by means of a fairness based scheduling algorithm. In addition, the simulation model of the proposed MAC scheme is realized by using OPNET Modeler network simulator. The results of the analytical calculations for the CBPs are compared to those of the simulation of the proposed MAC, thus validity of the MAC protocol is proved.

OFDMA-Based Medium Access Control for Next-Generation WLANs

EURASIP Journal on Wireless Communications and Networking, 2009

Existing medium access control (MAC) schemes for wireless local area networks (WLANs) have been shown to lack scalability in crowded networks and can suffer from widely varying delays rendering them unsuited to delay sensitive applications, such as voice and video communications. These deficiencies are mainly due to the use of random multiple access techniques in the MAC layer. The design of these techniques is highly linked to the choice of the underlying physical (PHY) layer technology. The advent of new PHY schemes that are based on orthogonal frequency division multiple access (OFDMA) provides new opportunities for devising more efficient MAC protocols. We propose a new adaptive MAC design based on OFDMA technology. The design uses OFDMA to reduce collision during transmission request phases and makes channel access more predictable. To improve throughput, we combine the OFDMA access with a carrier sense multiple access (CSMA) scheme. Data transmission opportunities are assigned through an access point that can schedule traffic streams in both time and frequency (subchannels) domains. We demonstrate the effectiveness of the proposed MAC and compare it to existing mechanisms through simulation and by deriving an analytical model for the operation of the MAC in saturation mode.

An OFDM-TDMA/SA MAC Protocol with QoS Constraints for Broadband Wireless LANs

Wireless Networks, 2006

Orthogonal frequency division multiplexing (OFDM) is an important technique to support high speed transmission of broadband traffic in wireless networks, especially broadband wireless local area networks (LANs). Based on OFDM, a new multiple access scheme, called OFDM-TDMA with subcarrier allocation (OFDM-TDMA/SA), is proposed in this paper. It provides more flexibility in resource allocation than other multiple access schemes such as OFDM-TDMA, OFDM-frequency division multiple access (OFDM-FDMA), and orthogonal frequency division multiple access (OFDMA). With OFDM-TDMA/SA, a medium access control (MAC) is designed for broadband wireless LANs. It optimizes bit allocation in subcarriers so that maximum bits are transmitted in each OFDM symbol under a frequency selective fading environment. The OFDM-TDMA/SA MAC protocol also supports three classes of traffic such as guaranteed, controlledload, and best effort services. Based on the optimum subcarrier bit-allocation algorithm and considering heterogeneous QoS constraints of multimedia traffic, a hierarchical scheduling scheme is proposed to determine the subcarriers and time slots in which a mobile terminal can transmit packets. In such a way, the OFDM-TDMA/SA MAC protocol significantly increases system throughput in a frequency selective fading environment and guarantees QoS of multimedia traffic. Computer simulation is carried out to evaluate the performance of the OFDM-TDMA/SA MAC protocol. Results show that the new MAC protocol outperforms other MAC protocols for OFDM-based wireless LANs. . Currently he is a senior researcher in Kiyon Inc., where he leads a research and development team working on MAC and routing protocols for wireless mesh networks, ad hoc networks, and sensor networks. His research interests include computer networking, cross-layer optimization, software radios, and communication protocols for next generation wireless networks, wireless sensor networks, wireless ad hoc and mesh networks, wireless LANs, and UWB networks. He is a member of IEEE, ACM and ACM SIGMOBILE.

Capacity Improvement and Analysis for Voice/Data Traffic over WLANs

IEEE Transactions on Wireless Communications, 2000

Voice over wireless local area network (VoWLAN) is an emerging application taking advantage of the promising voice over Internet Protocol (VoIP) technology and the wide deployment of WLANs all over the world. The real-time nature of voice traffic determines that controlled access rather than random access should be adopted. Further, to fully exploit the capacity of the WLAN supporting voice traffic, it is essential to explore statistical multiplexing and to suppress the large overhead. In this paper, we propose mechanisms to enhance the WLAN with voice quality of service (QoS) provisioning capability when supporting hybrid voice/data traffic. Voice multiplexing is achieved by a polling mechanism in the contention-free period and a deterministic priority access for voice traffic in the contention period. Header overhead for voice traffic is also reduced significantly. Delay-tolerant data traffic is guaranteed an average portion of service time in the long run. A session admission control algorithm is presented to admit voice traffic into the system with QoS guarantee. Analytical and simulation results demonstrate the effectiveness and efficiency of our proposed solutions.

Performance Evaluation of Medium Access Control Protocol for Wireless Networks

2011

When several independent terminals need to access a limited resource, a Medium Access Control (MAC) protocol is needed in order to manage and assign the resource. If no type of protocol is considered, conflicts could occur if more than one terminal wants to access the resource at the same time. Therefore, this work reports the analysis of MAC protocols. In addition to, we propose a protocol that handles transmission rates to maximize the transmission success rate. This proposed protocol is based on CSMA (Carrier Sense Multiple Access)-CDMA (Code Division Multiple Access). Simulations show that the protocol improves traffic transmission in the network, as compared with fixed rate mechanisms used to access the wireless medium.

Medium access control protocol design for wireless communications and networks review

International Journal of Electrical and Computer Engineering (IJECE), 2022

Medium access control (MAC) protocol design plays a crucial role to increase the performance of wireless communications and networks. The channel access mechanism is provided by MAC layer to share the medium by multiple stations. Different types of wireless networks have different design requirements such as throughput, delay, power consumption, fairness, reliability, and network density, therefore, MAC protocol for these networks must satisfy their requirements. In this work, we proposed two multiplexing methods for modern wireless networks: Massive multiple-input-multipleoutput (MIMO) and power domain non-orthogonal multiple access (PD-NOMA). The first research method namely Massive MIMO uses a massive number of antenna elements to improve both spectral efficiency and energy efficiency. On the other hand, the second research method (PD-NOMA) allows multiple non-orthogonal signals to share the same orthogonal resources by allocating different power level for each station. PD-NOMA has a better spectral efficiency over the orthogonal multiple access methods. A review of previous works regarding the MAC design for different wireless networks is classified based on different categories. The main contribution of this research work is to show the importance of the MAC design with added optimal functionalities to improve the spectral and energy efficiencies of the wireless networks.

A Centralized MAC Protocol with QoS Support for Wireless LANs

2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, 2007

Wireless Local Area Networks (WLANs) are widely used in homes and offices, as well as in public places, mainly as the last mile of an Internet connection, but also as an interconnection between different devices. This extensive usage of WLANs, with the need of modern applications (such as Voice over IP) for high throughput and low transmission delays, impose the necessity for efficient protocols with Quality of Service (QoS) support. In previous work [6] the ability of Multi Carrier-Code Division Multiple Access (MC-CDMA) based Medium Access Control (MAC) protocols to achieve high efficiency has been demonstrated. This paper presents a MAC protocol, based on MC-CDMA that uses an Access Point (AP) to centrally control the network and provide QoS support. Extensive simulation results and a comparison with the standard IEEE 802.11e[3] prove the efficiency of the proposed protocol.

ENHANCED BANDWIDTH UTILIZATION IN WLAN FOR MULTIMEDIA DATA Copyright IJAET

Deployment of wireless local area networks (WLANs) is growing consistently and demanding the support of multimedia applications with acceptable quality of service (QoS). This is attracting the interest of researchers globally. Under the optimum QoS, a number of VoIP calls can be supported by a WLAN. Distributed Coordination Function (DCF) and Point Coordination Function (PCF), two MAC protocols specified in the IEEE 802.11 standard have upper bound on VoIP connections. Under DCF mode 12 calls and in 20 calls in PCF mode[1,2,3,4]. In this paper we are proposing an access media mechanism in which audio data is transmitted in PCF mode and best-effort traffic in DCF mode. In the proposed access media mechanism, polling list is dynamically updated so that only those stations are polled which have voice packets ready to transmit. We have proposed a multi-queued MAC architecture for the access point. We considered voice traffic in CBR mode. The simulation results show that the maximum number of VoIP calls supported by 802.11b is 26 and 14 when inter arrival time for voice packets is 20 ms and 14 ms respectively.

Impact of the Transmission Scheme on the Performance in Wireless LANs

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2009

In wireless LANs, different multiuser access methods such as TDMA, OFDMA and SDMA are available which can be used with or without channel knowledge at the transmitter and a single antenna (MISO) or multiple antennas (MIMO) at the receiver. A cross-layer scheduler is considered which can be configured with these different PHY methods as well as with knowledge about application requirements and channel conditions at the MAC layer. The scheduler computes priorities on the MAC layer that are handed over to the physical layer in order to keep quality-of-service constraints such as throughput and delay. In this paper, it is demonstrated that controlling the priorities by a QoS aware resource allocation method allows to meet the requirements by the applications under various channel conditions. MISO-SDMA has a relatively small performance penalty in comparison to MIMO-SDMA which gives the best result. For MIMO-TDMA and-OFDMA, channel knowledge at the PHY layer does not result in essential performance enhancement.