Channel allocation schemes

About: Channel allocation schemes is a research topic. Over the lifetime, 10656 publications have been published within this topic receiving 182117 citations.

A dynamic channel assignment algorithm for a hybrid TDMA/CDMA-TDD interface using the novel TS-opposing technique

Abstract: It has been demonstrated that code division multiple access (CDMA) provides great flexibility by enabling efficient multiuser access in a cellular environment. In addition, time division duplex (TDD) as compared to frequency division duplex (FDD) represents an appropriate method to cater for the asymmetric use of a duplex channel. However, the TDD technique is subject to additional interference mechanisms compared to an FDD system, in particular if neighboring cells require different rates of asymmetry. If TDD is combined with an interference limited multiple access technique such as CDMA, the additional interference mechanism represents an important issue. This issue poses the question of whether a CDMA/TDD air-interface can be used in a cellular environment. The problems are eased if a hybrid time division multiple access (TDMA)/CDMA interface (TD-CDMA) is used. The reason for this is that the TDMA component adds another degree of freedom which can be utilized to avoid interference. This, however, requires special channel assignment techniques. A notable example of a system which uses a TD-CDMA/TDD interface is the Universal Mobile Telecommunications System (UMTS). This paper presents a novel centralized dynamic channel assignment (DCA) algorithm for a TD-CDMA/TDD air-interface. The DCA algorithm exploits a new technique which is termed "TS-opposing technique." The key result is that the new DCA algorithm enables neighboring cells to adopt different rates of asymmetry without a significant capacity loss.

Systems and methods for channel allocation for forward-link multi-user systems

Abstract: A method of allocating bandwidth is provided which involves for each sector of a plurality of sectors in a cell, using a respective subset of a total bandwidth; wherein for any two adjacent sectors, the respective subsets only partially overlap. A scheduling method is provided which involves for each sector, scheduling users for transmission on the respective subset of the total bandwidth by: for a given transmitter, allocating a respective fraction of capacity associated with the available bandwidth to each of at least two users selected from a plurality of users by performing an optimization for a selected scheduler design, the optimization selecting the at least two users and the optimization determining for each user the respective fraction of capacity; generating and transmitting a signal in which each of the at least two users has the respective fraction of capacity.

Efficient bandwidth allocation algorithm for ethernet passive optical networks

Abstract: Bandwidth allocation is one of the critical issues in Ethernet passive optical networks (EPONs). To achieve good network performance and thus provide guaranteed network service to end users, an EPON system must employ an efficient bandwidth allocation algorithm to dynamically allocate the limited bandwidth of the upstream transmission channel among multiple optical network units (ONUs). In the paper, an efficient bandwidth allocation algorithm for an EPON system is proposed. The proposed algorithm uses the multipoint control protocol (MPCP) defined by the IEEE 802.3ah Task Force to arbitrate the transmission of multiple ONUs, and incorporates a dynamic bandwidth allocation (DBA) scheme that makes use of the excessive bandwidth of lightly loaded ONUs to meet the bandwidth demand of heavily loaded ONUs. To improve bandwidth utilisation under high traffic load, an effective scheduling control mechanism is also incorporated to address the idle period problem. Through simulation experiments, it is shown that the proposed algorithm can significantly improve the network performance in terms of packet delay, queue length, and throughput under high traffic load as compared with a well-known DBA algorithm in the literature.

Centralized Scheduling and Channel Assignment in Multi-Channel Single-Transceiver WiMax Mesh Network

Abstract: The IEEE 802.16a standard defines WiMax mesh network, using the base station (BS) as a coordinator for the centralized scheduling. This paper proposes a centralized scheduling algorithm for WiMax mesh networks. In our scheme, each node has one transceiver and can be tuned between multiple channels, intending to eliminate the secondary interference for reducing the length of scheduling. We first study the problem when sufficient channels are supported, then extend our solution to the case with insufficient number of channels. Both the scheduling algorithm and the channel assignment strategies are included. The simulation results show that the multi-channel single-transceiver MAC can reduce the length of scheduling substantially as compared with the single channel system, and double channel may provide a performance similar to the multiple channels.

Quality-of-service provisioning system for multimedia transmission in IEEE 802.11 wireless LANs

Abstract: IEEE 802.11, the standard of wireless local area networks (WLANs), allows the coexistence of asynchronous and time-bounded traffic using the distributed coordination function (DCF) and point coordination function (PCF) modes of operations, respectively. In spite of its increasing popularity in real-world applications, the protocol suffers from the lack of any priority and access control policy to cope with various types of multimedia traffic, as well as user mobility. To expand support for applications with quality-of-service (QoS) requirements, the 802.11E task group was formed to enhance the original IEEE 802.11 medium access control (MAC) protocol. However, the problem of choosing the right set of MAC parameters and QoS mechanism to provide predictable QoS in IEEE 802.11 networks remains unsolved. In this paper, we propose a polling with nonpreemptive priority-based access control scheme for the IEEE 802.11 protocol. Under such a scheme, modifying the DCF access method in the contention period supports multiple levels of priorities such that user handoff calls can be supported in wireless LANs. The proposed transmit-permission policy and adaptive bandwidth allocation scheme derive sufficient conditions such that all the time-bounded traffic sources satisfy their time constraints to provide various QoS guarantees in the contention free period, while maintaining efficient bandwidth utilization at the same time. In addition, our proposed scheme is provably optimal for voice traffic in that it gives minimum average waiting time for voice packets. In addition to theoretical analysis, simulations are conducted to evaluate the performance of the proposed scheme. As it turns out, our design indeed provides a good performance in the IEEE 802.11 WLAN's environment, and can be easily incorporated into the hybrid coordination function (HCF) access scheme in the IEEE 802.11e standard.