Adaptive Modulation and Coding

Redundant robotic manipulators offer enhanced flexibility, dexterity, and fault tolerance compared to conventional robotic systems. However, this redundancy also introduces significant complexity in motion planning and obstacle avoidance, particularly in dynamic environments where obstacles may move unpredictably. This article presents a conceptual discussion of an adaptive meta-heuristic control strategy designed for real-time obstacle avoidance in redundant robotic manipulators. By emphasizing adaptability, real-time responsiveness, and intelligent control coordination, the proposed strategy enables safe and efficient manipulation in uncertain and dynamically changing workspaces. The discussion avoids algorithmic and mathematical details, focusing instead on system-level design principles, operational benefits, and implications for advanced robotic applications.

In this paper, we exploit the potential of positioning technologies in wireless broadband communications, which are based on worldwide interoperability for microwave access (WiMAX), in particular the IEEE802.16* standards. By utilizing the additional features in WiMAX including multiple input multiple output (MIMO), adaptive modulation and coding (AMC), beamforming, relay station and power control, we believe that the features can be used for enhancing the location estimation accuracy in location services.

WiMAX technology is based on the IEEE 802.16 specification of which IEEE 802.16-2004 and 802.16e amendment are Physical (PHY) layer specifications. IEEE 802.16-2004 currently supports several multiple-antenna options including Space-Time Codes (STC), Multiple-Input Multiple-Output (MIMO) antenna systems and Adaptive Antenna Systems (AAS). The most recent WiMAX standard (802.16e) supports broadband applications to mobile terminals and laptops. Using Adaptive Modulation and Coding (AMC) we analyze the performance of OFDM physical layer in WiMAX based on the simulation results of Bit-Error-Rate (BER), and data throughput. The performance analysis of OFDM-PHY is done. In this paper, an extension to the basic SISO mode, a number of 2x2 MIMO extensions are analysed under different combinations of digital modulation (QPSK, 16-QAM and 64-QAM) and Convolutional Code (CC) with 1/2 , 2⁄3 and 3/4 rated codes. The intent of this paper is to provide an idea of the benefits of multiple antenna systems over single antenna systems in WiMAX type deployments.

Cognitive radio has been considered as a key technology toward future wireless communications due to better spectrum efficiency by accommodating secondary user system(s). We observe modern wireless communication systems widely applying adaptive modulation and coding (AMC) based on signal strength/quality, which has been ignored in earlier wireless networking research, and we call it as rate-distance nature. By pioneer introducing the rate-distance properties to slotted ALOHA multiple access (as an example of multiple access protocols) to mitigate interferences from the secondary system(s) to primary systems, we successfully demonstrate optimization of the secondary system's throughput, while maintain the primary system unchanged. Consequently, we optimize the spectrum throughput of the entire cognitive radio networks via joint physical and medium access control, rather than just spectrum utilization/efficiency at the physical layer.

Very high throughput satellites (VHTS) are the new trend in satellite communications systems in order to satisfy the increasing demand for both higher throughput and ubiquitous connectivity. Implementing an IP interactive network over a VHTS would enable the satellite to compete with terrestrial networks by offering ubiquitous added value services for end-user traffic. Even so, the simulations presented in this paper show that a 30% of throughput can be lost due to co-channel interferences. In existing interactive satellite networks such as REDSAT or AmerHis, the return uplink transmissions are inherently benefited from the MF-TDMA scheduling to mitigate the co-channel interferences present in VHTS. In such networks dynamic resource assignation (DAMA) is executed at each SuperFrame period (<100 ms). Therefore, any feasible optimization on the scheduling shall be performed in real time. In this paper, two parallel problems are faced at the same time: co-channel interference mitigation and real time scheduling. In particular, two novel interference-aware scheduling algorithms for a DVB-RCS2 return uplink are presented. Despite other previous works, the proposed algorithms are designed on the basis to be executed in real time on a fixed SuperFrame period basis. The performance assessment of the proposed algorithms is carried out through system-level simulations based on realistic satellite scenarios and interactive traffic models using DAMA in real time.

This document presents a practical interoperability test suite for CDMA2000 1xEV-DO (IS-856) wireless terminal devices. It consolidates laboratory and field procedures that validate system acquisition and idle operation, session and address management (UATI/RATI), access authentication (PPP-CHAP), control-channel overhead supervision, location update behavior, idle-state channel hashing, dual-idle operation with 1x/EV-DO, and voice/SMS interactions across Idle, Dormant, and Connected states. It further specifies active/dormant inter-system handoffs between EV-DO and 1x, power-save behavior, and forward/reverse link throughput measurements under relay/network models using Simple IP and Mobile IP. Each test includes a clear definition, step-by-step method of measurement, and minimum standard or pass criteria to support repeatability and carrier-grade reporting. The intent is implementation guidance rather than a normative specification.

This paper investigates iterative frequency domain technieques for the reception of spatially multiplexed single carrier signals transmitted over frequency-selective multiple input multiple output (MIMO) channels. The investigated equalizers are based on the softcancellation (SC) and minimum mean square error (MMSE) filtering technique for turbo-coded single carrier point-to-point MIMO systems. We consider two different transmit antenna separation techniques in the frequency domain: (1) antenna-by-antenna (AA) and (2) joint over antenna techniques (JA). (1) aims to separate signals in different layers by MMSE filtering antenna-by-antenna, whereas (2) aims to detect the composite signal comprised of the signals transmitted from the multiple antennas. In (2) the composite received signal is decomposed by using the spatial maximum aposteriori probability (MAP) algorithm. We evaluate performances in terms of frame error rate (FER) and troughput in pointto-point MIMO frequency-selective fading channels. Impacts of spatial correlation on performance of the two detectors are also investigated in this paper.

We carry out a comprehensive analysis of a range of wireless network efficiency considerations. Firstly, we explore the properties and the implications of the power-versus bandwidthefficiency criteria. Secondly, we perform a detailed top-down analysis of a typical commercial wireless network, which emphasizes the inherent differences between the aforementioned two efficiency metrics, while demonstrating that the appropriate choice of the network optimization criterion can have a profound effect on the overall network performance. Finally, we address the issue of resource management and its impact on the definition of the overall system efficiency. Acknowledgements: The work reported in this paper has formed part of the Delivery Efficiency Core 4 Research Programme of the Virtual Centre of Excellence in Mobile & Personal Communications, Mobile VCE, www.mobilevce.com. Fully detailed technical reports on this research are available to Industrial Members of Mobile VCE.

systems have evolved Q3 considerably in recent years, encouraging the deployment of multiple systems or multi-cellular technology, and improving the quality of service (QoS) offered to mobile users. For example 4G systems offers better quality of service than that offered by 3G and 3.5G. Furthermore, 4G systems, such as Long Term Evolution (LTE) also offers expanded cellular coverage and provides higher throughput. Such emerging systems certainly enhance the overall accessibility Internet, and enabling such networks to handle both new and migrating fixed users becomes a challenge. This paper evaluates system performance by developing a new LTE mechanism for allocating resources in the downlink based on call admission control (CAC) taking into account mobility within and between cellular users. The proposed mechanism uses adaptive modulation and coding (AMC) that divides the geographical area into several concentric regions. With this mechanism each call accepted by the system maintains its initial throughput regardless of the position of the user in the cell.

As new cellular networks support not only voice services but also many multimedia applications, the requirements for reliable data transmission at high speeds create heavy load on the system. Even though LTE/LTE-A technology takes action towards alleviating this load, it is still necessary to manage resources effectively because of the inadequacy of the available radio resources. Thus, the scheduler at the MAC layer of the base station plays a very important role in resource allocation to the user. In this study a novel algorithm for resource allocation in mobile environments is presented, with two variations addressing different input traffic. The idealized case (I-MAS algorithm) relates to the full-buffer model, while the realistic case (R-MAS algorithm) takes into consideration the specific characteristics of the incoming user traffic. The paper includes performance evaluation of the suggested algorithms in terms of mean and edge throughput, system fairness, and BLER and comparison with well-known algorithms like the round robin (RR) and best CQI (B-CQI) (full-buffer model) and their extensions for real-life traffic models, RR Traffic and B-CQI Traffic, respectively. When the simulation results are examined, it can be seen that the I-MAS and R-MAS algorithms maximize the throughput while at the same time distributing the resources fairly among the users. They also prove to be quite robust in mobile environments even at higher user speeds.

This document provides team PHY System proposal of a low frequency (Sub 11 GHz) wireless access PHY for point-to-multipoint voice, video and data applications. The submission is for consideration of the Task Group to develop a PHY standard for BWA system. This contribution will be presented and discussed within the Task Group in Session #11 for possible adoption as baseline for a PHY standard Sub 11 GHz BWA. This document has been prepared to assist IEEE 802.16. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. The contributor grants a free, irrevocable license to the IEEE to incorporate text contained in this contribution and any modifications thereof in the creation of an IEEE Standards publication; to 2001-01-18 IEEE 802.16.3c-01/08 1 contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE's name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE's sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.16. The contributor is familiar with the IEEE 802.16 Patent Policy and Procedures (Version 1.0) <http, including the statement "IEEE standards may include the known use of patent(s), including patent applications, if there is technical justification in the opinion of the standards-developing committee and provided the IEEE receives assurance from the patent holder that it will license applicants under reasonable terms and conditions for the purpose of implementing the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication.

Thanks to the facilities offered by telecommunications, telemedicine today allows physicians and clinicians to access, monitor and diagnose patients remotely. Telemedicine includes several applications such as remote monitoring of chronically ill patients, monitoring people in their everyday lives to provide early detection and intervention for various types of diseases, computer-assisted physical rehabilitation in ambulatory settings, and assisted living for the elderly at home, as well as remote monitoring of injured people in a postdisaster situation. These new applications require a reliable, wireless communication link between the devices implanted in the patient's skin and a clinician. In this article, this issue is discussed and a list of performance criteria for the different communication links used are addressed, especially focusing on the satellite link. Then an adaptive air interface which is designed to meet the performance constraints of bidirectional satellite communication links in an emergency situation in Ku/Ka/Q/V bands where when strong channel impairments occur is described and analysed.

Vertical handover (VHO) procedure facilitates service continuity in a heterogeneous wireless scenario under varying network as well as channel conditions. Decision criteria for VHO are, mainly, designed to maximize a combination of network parameters in order to guarantee a satisfying quality of service and maximize network operators and/our users expectation. The objective of this work is to formalize the VHO decision criteria as a QoS constrain bound problem and propose two strategies that permits to achieve QoS constrains without wasting resources. The former that minimize the power consumption and the latter that minimize the number of VHO. Numerical results are provided in order to compare the two strategies.

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Bit interleaved coded multiple beamforming (BICMB) was previously designed to achieve full spatial multiplexing of min(N, M ) and full spatial diversity of NM for N transmit and M receive antennas over flat fading channels. Furthermore, BICMB when combined with orthogonal frequency division multiplexing (OFDM) achieves full spatial multiplexing and full diversity order of NML over L-tap frequency-selective channels. BICMB requires full channel state information (CSI) both at the transmitter and receiver, however it uses uniform power and rate over the parallel channels established by multiple beamforming. In this paper, our main goal is to investigate the performance of the previously analyzed BICMB system via adaptive modulation and coding (AMC) to further utilize CSI and to improve system throughput performance. Hence, we name the new systems as Adaptive BICMB (ABICMB) over flat fading, and ABICMB-OFDM over frequency-selective channels. Simulation results show that adaptive system achieves 4-13 dB performance gain compared to non-adaptive case depending on the antenna configuration and environment. Systems analyzed require perfect CSI both at the transmitter and receiver, which may be difficult to obtain in a practical scenario. However, high performance gains achieved makes it worthwhile to study the performance of the proposed systems, leaving room for significant gain with limited feedback.

Bit interleaved coded multiple beamforming (BICMB) was previously designed to achieve full spatial multiplexing of min(N, M ) and full spatial diversity of NM for N transmit and M receive antennas over flat fading channels. Furthermore, BICMB when combined with orthogonal frequency division multiplexing (OFDM) achieves full spatial multiplexing and full diversity order of NML over L-tap frequency-selective channels. BICMB requires full channel state information (CSI) both at the transmitter and receiver, however it uses uniform power and rate over the parallel channels established by multiple beamforming. In this paper, our main goal is to investigate the performance of the previously analyzed BICMB system via adaptive modulation and coding (AMC) to further utilize CSI and to improve system throughput performance. Hence, we name the new systems as Adaptive BICMB (ABICMB) over flat fading, and ABICMB-OFDM over frequency-selective channels. Simulation results show that adaptive system achieves 4-13 dB performance gain compared to non-adaptive case depending on the antenna configuration and environment. Systems analyzed require perfect CSI both at the transmitter and receiver, which may be difficult to obtain in a practical scenario. However, high performance gains achieved makes it worthwhile to study the performance of the proposed systems, leaving room for significant gain with limited feedback.

Re: Call for Contributions: Initial PHY Proposals (IEEE 802.16.3-00/24) Abstract A PHY is proposed for 802.16.3 in which modulation format and coding rate can be adjusted on a block by block basis to provide optimum channel utilization for the widest range of channel conditions. Purpose This proposal is offered as a PHY layer for the 802.16.3 Task Group Notice This document has been prepared to assist IEEE 802.16. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release The contributor grants a free, irrevocable license to the IEEE to incorporate text contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it...