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TDMA - CDMA
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Implementation and Evaluation of a TDMA MAC for WiFi-Based Rural Mesh Networks
WiFi mesh networks with outdoor links have become an attractive option to provide cost-effective broadband connectivity to rural areas, especially in developing regions. It is well understood that a TDMA-based approach is necessary to provide good performance over such networks. While preliminary prototypes of TDMA-based MAC protocols have been developed, there is no implementation-based validation/ evaluation in multi-hop settings. In this work, the author describes the elements of a multi-hop MAC implementation based on the open-source MADWIFI driver. The paper also presents an evaluation, with a detailed accounting of the various overheads, on a 4-hop (5-node) path. The paper shows that the implementation has no system overheads, achieves good throughput, and low delay/jitter.
170 days ago by Association for Computing Machinery3G Coming to Ukraine
The 3G family of standards such as WCDMA or UMTS has been developed by International Telecommunication Union (ITU), and is otherwise called International Mobile Telecommunications 2000 (IMT-2000). It covers 5 smaller standards, namely: WCDMA, CDMA2000, TD-CDMA/TD-SCDMA, DECT and UWC-136. According to the IMT-2000 standard, the 3rd generation mobile connection should be provided in an integrated network capable of data transfer: not less than 144 Kbps for highly mobile users (up to 75 miles per hour), 384 Kbps for low mobile users (up to 1.8 mile per hour), and 2.048 Mbps for immobile users within short distances.
445 days ago byExperimental Triple-Play Service Delivery Using Commodity Wireless LAN Hardware
This paper studies the feasibility of utilizing Wireless Local Area Network (WLAN) technology to deliver the Triple-Play services (video, voice and data) over a specific system model. Existing protocols are shown to not efficiently manage the wireless channel therefore one proposes a new Triple-Play Time Division Multiple Access (TP-TDMA) Media Access Control (MAC) protocol to provide Quality of Service (QoS) for these Triple-Play services in a point-to-multipoint network over an existing 802.11a physical layer. Through extensive simulation analysis, the protocol is shown to offer better performance than the 802.11e Enhanced Distributed Coordination Function (EDCF). Moreover, this protocol is implemented in hardware using the MADWiFi driver to verify the real-world performance. Both results of the simulation study and hardware implementation are provided.
564 days ago by University of Western OntarioCDMA and OFDM: The Convergence of Wireless Broadband Services
The one technology fits all approach will not suffice in the future competitive telecommunications market. Operators will leverage the most appropriate technology for a particular application or service. In most instances, 3G CDMA will remain the leading and most economical platform for the delivery of mobile broadband services.
599 days ago by CDMA Development Group (CDG)Performance of Transmission Spaced Selection Diversity in DS-CDMA Systems
The performance of transmission spaced Selection Diversity (SD) placed at Base Station (BS) in DS-CDMA system remains insufficiently clear. This performance will be evaluated by considering the effect of space distance between antennas and the maximum Doppler frequency (fd) on Bit Error Rate (BER) performance under optimum conditions which are not clarified until now. Moreover, analysis of this system is presented under the effect of Rayleigh fading.
703 days ago byInterference Management for Medium Access Control in CDMA Underwater Acoustic Sensor Networks
One of the major challenges for the deployment of Underwater Acoustic Sensor Networks (UASN) is the design of a suitable Medium Access Control (MAC) protocol, and CDMA has been earmarked as the most promising candidate. While several works have considered the problems of allocation of code and transmission power separately, this paper, proposes a receiver-centric interference management approach for joint code/power assignment for MAC in CDMA UASNs. Through extensive numerical simulations, the paper illustrates its efficacy and demonstrate its superiority to conventional transmitter-centric approaches, for both fixed-power code assignments and joint code/power assignments.
762 days ago by Trinity College DublinThe 3G Evolution: Taking CDMA2000 Into the Next Decade
Proving the business case for 3G (third-generation) wireless networks is sometimes considered to be a daunting challenge since it is assumed that 3G requires a massive amount of new hardware, large capital commitments, and new spectrum, all of which are further compounded by interoperability constraints between newly-deployed 3G networks and existing 2G networks. Nothing could be further from the truth. From its inception, the CDMA2000 evolutionary path was designed to minimize the impact of its introduction into an operator's network.
1633 days ago by CDMA Development GroupFurther Vision on TD-SCDMA Evolution
As the data rate of the mobile service increases fast, 2Mbps is not enough any more for Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). While the new B3G system to provide high data rate service is still in research, TD-SCDMA must be enhanced and evolved to provide higher data rate service with better QoS. Considering the status of Long Term Evolution (LTE) of 3G, which is been researching and standardizing in 3GPP, the evolution map of TD-SCDMA is presented in this paper, and the requirement on TD-SCDMA LTE and the potential features of LTE TDD is presented.
1714 days ago by Beijing University of Posts and TelecommunicationsAn Efficient Circulant MIMO Equalizer for CDMA Downlink: Algorithm and VLSI Architecture
Wireless communication is experiencing radical advancement to support broadband multimedia services and ubiquitous networking via mobile devices. MIMO (Multiple Input Multiple Output) technology using multiple antennas at both the transmitter and receiver has emerged as one of the most significant technical breakthroughs for throughput enhancement. This paper presents an efficient circulant approximation based MIMO equalizer architecture for the CDMA downlink.
1751 days ago by Rice UniversityEnabling CDMA 1X Data Roaming
CDMA wireless technology is generally available worldwide but is non-existent in Western Europe. Subscribers of CDMA networks who are reliant on wireless connectivity for data services are demanding that they have ubiquitous access, even when in Europe. Without this ability, their only option is to change their CDMA device for a GPRS device or to carry two devices. Likewise, the reverse case exists for users from Europe with GPRS devices who want to access CDMA-based data services in North America. While CDMA carriers have been rolling out CDMA2000 packet data networks, Wi-Fi has started to become a popular access technology within the home and the enterprise.
1753 days ago by Bridgewater Systems
