In this paper, a medium access control protocol is proposed for the integrated voice and data services in the local CDMA communication systems. Based on WB-TD/CDMA, uplink channels for the proposed protocol are composed of time slots with multiple spreading codes for each slot. During a talkspurt, a voice terminal transmits its entire packets over a reserved code. On the other hand, a data terminal transmits its packet after sensing the spreading code status. The base station broadcasts the status of spreading codes for each slot. In this protocol, voice packets never contend with data packets. The numerical results show that this protocol increases the system capacity for voice service by applying the reservation scheme. Despite the low access priority of data terminal, the data traffic performance can be increased in proportion to the number of spreading codes.

In designing WLAN MAC protocols, several issues must be considered. Among them, the hidden-terminal and exposed-terminal problems are two of the most important issues. The hidden-terminal problem has been analyzed by many researchers and significant improvements have been made. The exposed-terminal problem, however, has not been fully considered in the design of WLAN MAC protocols. In this paper, we propose two protocols. In the first one, referred to as channel splitting protocol, the channel is split into two subchannels--the control channel and the data channel--to solve several problems inherent in existing protocols, including hidden terminal and exposed terminal problems. With channel splitting, a control frame is transmitted through the control channel alternatively of a data frame which is transmitted through the data channel. In the second protocol, referred to as RTR/ATR reservation protocol, hosts that want to transmit data reserve several slotted data channels in advance to increase performance, while the first protocol reserves only one transmission. In the second protocol, control frames are transmitted through the control channel independently of data frames. The performance of the proposed protocols is evaluated by simulation and compared with existing protocols.

Efficient radio resource utilization and fairness are important goals that must be achieved since wireless ATM systems support various services with different traffic characteristics such as CBR and UBR. This paper proposes a novel delay-and-queuing data size-based MAC protocol for broadband wireless ATM. The proposed MAC protocol relies on a new resource scheduling algorithm that decides the priority of channel assignment based on both the queuing delay and the queuing data size in the transmission buffer. Simulation results confirm that the proposed MAC protocol is able to provide throughput fairness and to achieve excellent throughput performance for ATM services that experience dynamic traffic fluctuations.

Developments in new frequency bands for wireless communications make a broadband channel for new services possible. Great effort has been made researching and developing broadband wireless communication in the 60-GHz millimeter-wave band since the early 1990s. In this paper, we design an ATM (asynchronous transfer mode)-based indoor millimeter-wave wireless local area network (WLAN) that supports multimedia transmissions and focus on the wireless access topic for implementation of wireless ATM. We propose an integrated multimedia transmission protocol, based on the MAC (medium access control) protocol, called RS-ISMA (reservation-based slotted idle signal multiple access). It supports CBR (constant bit rate), VBR (variable bit rate), ABR (available bit rate) and UBR (unspecified bit rate) transmissions and provides QoS (quality of service)-dependent adaptive retransmissions. An RS-ISMA-based prototype full-duplex indoor high-speed WLAN in the 60-GHz band was developed.

A hybrid CDMA/TDMA, a combination of CDMA and TDMA, is proposed as a MAC protocol for wireless ATM networks. TDMA offers the ability to integrate different types of services in a flexible way by the use of multiple slots per frame, while CDMA allows multiple users to transmit simultaneously using their own codes. To reduce the multiple access interference in each slot, the channel access is controlled by an access permission probability or a round robin method. A shared code scheme is adopted to utilize the given code resource efficiently. The results of simulation show that the proposed scheme gives better performance than the JCP algorithm.

Recent progress in the optical transmission technology makes an ATM passive optical network (APON) a good candidate for access networks. APON based on tree topology requires efficient medium access control (MAC) to multiplex upstream data flows efficiently while not disturbing the original pattern. In this paper, we proposed a Window-based permit distribution scheme for the MAC protocol of APON. It derives the rate of generated cell during one spacing window by the unit called time segment, and spaces permits not to cluster the cells in upstream transmission. The purpose of the proposed scheme is to make the permit arrival rate close to the cell arrival rate, so, reduces the CDV even if under the various kinds of bursty traffic. In addition, the proposed scheme does not require the additional MAC overhead for cell arrival timing information. The result of simulation shows that the performance of proposed protocol is better than current protocols in terms of transfer delay and 1-point CDV.

Recent progress in the optical transmission technology makes an ATM passive optical network (APON) a good candidate for access networks. APON based on tree topology requires efficient medium access control (MAC) to multiplex upstream data flows efficiently while not disturbing the original pattern. In this paper, we proposed a Window-based permit distribution scheme for the MAC protocol of APON. It derives the rate of generated cell during one spacing window by the unit called time segment, and spaces permits not to cluster the cells in upstream transmission. The purpose of the proposed scheme is to make the permit arrival rate close to the cell arrival rate, so, reduces the CDV even if under the various kinds of bursty traffic. In addition, the proposed scheme does not require the additional MAC overhead for cell arrival timing information. The result of simulation shows that the performance of proposed protocol is better than current protocols in terms of transfer delay and 1-point CDV.

The channel throughput and packet delay of wireless medium access control (MAC) protocols with Rayleigh fading, shadowing and capture effect are analyzed. We consider CSMA/CA protocols as the wireless MAC protocols, since CSMA/CA protocols are based on the standard for wireless Local Area Networks (LANs) IEEE 802. 11. We analyze the channel throughput and packet delay for three types of CSMA/CA protocols; Basic CSMA/CA, Stop-and-Wait CSMA/CA and 4-Way Handshake CSMA/CA. We calculate the capture probability of an Access Point (AP) in a channel with Rayleigh fading, shadowing, and near-far effects, and we derive the throughput and packet delay for the various protocols. We have found that the performance of CSMA/CA in a radio channel model is 50 percent less than in an error free channel model in low traffic load, while the throughput and packet delay of CSMA/CA in a radio channel model show better performance than in an error free channel model in high traffic load. We also found that the 4-Way Handshake CSMA/CA protocol is superior to the other CSMA/CA protocols in high traffic load.

In this paper, we propose a modified R-ISMA (reserved idle signal multiple access) protocol for a wireless local area network (WLAN) with a hybrid system construction. The protocol can support a basic service area as large as that supported by a centralized system and allows the direct transmission between neighbor stations as in a distributed system without the problem of hidden terminals. Since a polling scheme is used during transmission of information packets, an ARQ (auto repeat request) scheme is easily applied. A dynamic analysis using transient fluid approximation analysys is used for performance evaluation. In the analysis, we use Fritchman channel model to describe a burst error environment. Some numerical examples using a set of practical system parameters are given. It is shown that the system performance is improved compared with a centralized system with R-ISMA.