ADAPTIVE MODULATION AND CODING FOR WIMAX SYSTEMS

This project is on design and implementation of adaptive modulation in Wimax systems for broadband wireless networks. The majority of the work done is on acquiring the cannel signal to noise ratio (SNR) and comparing two pilot aided SNR estimation techniques with a blind estimator. Reddy Noise power estimator and Subspace based estimator are pilot aided, both of which are a combination of channel estimation and noise estimation. The third is a blind autocorrelation based Linear Predictor Interpolator. Fixed transmission systems make use of average modulation and coding which has reasonable performance in both high and low SNR conditions in the communication channel. This results in channel bandwidth under-utilization in high SNR conditions. The use of adaptive modulation improves the spectral efficiency by making use of variable bit loading, depending on the prevailing SNR.A higher modulation and coding rate is used in high SNR conditions, while a lower and noise robust is used in low SNR conditions. The main task of the project is to do a performance analysis of SNR estimation algorithms by implementing each on the IEEE 802.16d standard for broadband wireless local and metropolitan area networks (WMAN) working model. The SNR estimation technique which results in optimal performance will later be used to in a feedback system which inputs the channel SNR into a control mechanism that makes the decision to switch modulation and coding rate based on a predetermined SNR threshold value for each rate that ensures acceptable bit error rate (BER). First the SNR estimation using the three algorithms is implemented in Wimax system, based on the transmission protocols specified in Wimax. The performance of the estimators is then compared by determining the mean square error and computation time for each as the performance criteria and to compare the performance of the unaided SNR estimator in comparison to the conventional pilot aided SNR estimators

Adaptive Modulation and Coding and Cooperative ARQ in a Cognitive Radio System

In this paper, a joint cross-layer design of adaptive modulation and coding (AMC) and cooperative automatic repeat request (C-ARQ) scheme is proposed for a secondary user in a shared-spectrum environment. First, based on the statistical descriptions of the channel, closed-form expressions of the average spectral efficiency (SE) and the average packet loss rate (PLR) are presented. Then, the cross-layer scheme is designed, with the aim of maximizing the average SE while maintaining the average PLR under a prescribed level. An optimization problem is formed, and a sub-optimal solution is found: the target packet error rates (PER) for the secondary system channels are obtained and the corresponding sub-optimal AMC rate adaptation policy is derived based on the target PERs. Finally, the average SE and the average PLR performance of the proposed scheme are presented

analisis penerapan adaptive modulation and coding pada sistem ofdm uwb untuk area indoor

ABSTRAKSI: Pertumbuhan komunikasi wireless mendorong meningkatnya pemenuhan kebutuhan disisi pengguna dalam hal layanan data kecepatan tinggi secara real time, memperbaiki kualitas sinyal dan peningkatan data rate serta mengatasi masalah yang khas dalam sistem komunikasi itu sendiri yaitu interferensi. UWB (Ultra-Wideband) merupakan salah satu solusi untuk memenuhi kebutuhan tersebut karena sistem komunikasi UWB memiliki banyak keuntungan diantaranya: (a) Data rate yang tinggi (b) Path loss yang rendah dan lebih tahan terhadap multipath propagation (c) Transceiver yang lebih sederhana dan murah (d) Daya kirim yang rendah dan low interference (e) Keamanan transmisi. Federal Communication Commission (FCC) telah menetapkan bahwa frekuensi operasi UWB adalah (3.1 – 10.6) GHz, menunjukkan karakteristik sistem komunikasi UWB adalah bandwidth nya sangat lebar. FCC telah menetapkan bahwa bandwidth minimum untuk sistem UWB adalah 500 MHz. Permasalahan muncul ketika dihadapkan dengan kanal propagasi. Sinyal yang ditransimisikan melalui kanal akan dirusak secara statistik oleh derau Gaussian (AWGN). Hal yang lebih ekstrim dalam kanal wireless adalah noise eksternal dan interferensi yang pengaruhnya lebih signifikan dibandingkan AWGN, di mana kondisi tersebut dipandang sebagai kanal multipath fading. Untuk mengatasi masalah tersebut dibutuhkan suatu cara agar sistem UWB mampu menyesuaikan terhadap kondisi kanal yang fluktuatif tersebut, salah satu cara yaitu dengan penerapan teknik adaptive modulation and adaptive coding pada UWB. Adaptive modulation memungkinkan sistem untuk merubah-rubah skema modulasi berdasarkan fluktuasi kondisi kanal radio. Dari hasil simulasi dapat dilihat bahwa sistem OFDM UWB adaptive memberikan performansi yang lebih baik dibandingkan sistem OFDM UWB non adaptive dalam efisiensi bandwidth maupun efisiensi daya. Hal tersebut diperlihatkan oleh hasil simulasi yaitu: (a). Pada kondisi CM yang tetap untuk mencapai BER 10-4 dibutuhkan SNR sebesar 7dB untuk modulasi 16-QAM, ini menunjukan dicapainya efisiensi bandwidth sebesar 2.5% (b). Pada kondisi CM yang variable, untuk target BER 10-4 dicapai pada SNR 5.5dB, ini menunjukan dicapainya efisiensi daya (SNR) sebesar 2.05%.Kata Kunci : OFDM UWB, Adaptive Modulation and Coding, CM.ABSTRACT: Wireless communication development effects the grow of user needs in service of high-speed real time data transfer, solve the problem of signal quality and improve data rate, and also fix interference -the specific problem of communication system itself. UWB (Ultra- Wideband) is one of solution to fulfill that necessity because UWB communication system has many advantages, like: (a) High data rate (b) Low path loss and more stable from multipath propagation (c) simpler and cheaper transceiver (d) Low power transmit and low interference (e) Transmission security. Federal Communication Commission (FCC) decided that range UWB operation frequency is 3.1 GHz - 10.6 GHz, shown the very wide bandwidth as characteristic of UWB communication system. FCC decided that minimum bandwidth for UWB system is 500 MHz. The problems occur when the system faced propagation channel. Signal that transmits through the channel will be statistically destroyed with Gaussian Noise (AWGN). More extreme thing in wireless channel is external noise and the interference which has more significant effect than AWGN, where that condition known as multipath fading channel. Solution needed to solve that problem in order UWB system can fit with fluctuate channel condition, one of the solutions is using adaptive modulation and adaptive coding technique in UWB. Adaptive modulation make the system possible to change modulation scheme base on radio channel fluctuate condition. Simulation’s report showed that adaptive OFDM UWB system gave better performance than non-adaptive OFDM UWB system, both bandwidth and power efficiency. Its shown in simulation’s report: (a) For 16-QAM modulation, 7 dB of SNR is needed to get BER 10-4 on fix CM condition, its inform that bandwidth efficiency is reached 2.5% (b) On variable CM condition, 5.5 dB of SNR is needed to get BER 10-4, its inform that SNR efficiency is reached 2.05%.Keyword: OFDM UWB, Adaptive Modulation and Coding, CM

Receiver diversity with selection combining for drone communication around buildings at frequency 10 GHz

The communication network for cellular network keep development. This research analyzed about cellular network was used drone network. The mobile drone used frequency at 10 GHz for communication. The mobile drone moved around buildings. Buildings were used high variation. Base Station placed around building. This research was using macro diversity Base Station, variation building, variation modulation, and variation height of drone trajectory. Macro diversity mechanism used for that two Base Station. Selection Combining (SC) method was used for that macro diversity mechanism. The modulation communication based from Adaptive Modulation and Coding (AMC). Adaptive Modulation and Coding (AMC) was used Modulation and coding scheme (MCS). Modulation was used QPSK, 16 QAM, and 64 QAM. As the result described signal to noise ratio (SNR) at every node communication, probability MCS, and percentage coverage of drone trajectory. MCS probability for 64 QAM become increased with selection combining method. The percentages coverage of drone trajectory was obtained 77.2% of the first BS, 66.8% of the second BS, and 87.2% with SC method.The communication network for cellular network keep development. This research analyzed about cellular network was used drone network. The mobile drone used frequency at 10 GHz for communication. The mobile drone moved around buildings. Buildings were used high variation. Base Station placed around building. This research was using macro diversity Base Station, variation building, variation modulation, and variation height of drone trajectory. Macro diversity mechanism used for that two Base Station. Selection Combining (SC) method was used for that macro diversity mechanism. The modulation communication based from Adaptive Modulation and Coding (AMC). Adaptive Modulation and Coding (AMC) was used Modulation and coding scheme (MCS). Modulation was used QPSK, 16 QAM, and 64 QAM. As the result described signal to noise ratio (SNR) at every node communication, probability MCS, and percentage coverage of drone trajectory. MCS probability for 64 QAM become increased with selection combining method. The percentages coverage of drone trajectory was obtained 77.2% of the first BS, 66.8% of the second BS, and 87.2% with SC method

ANALISIS PENGARUH ADAPTIVE MODULATION AND CODING (AMC) TERHADAP PERFORMANSI SISTEM BROADBAND WIRELESS WiMAX 802.16e

ABSTRAKSI: Kebutuhan layanan nirkabel untuk saat ini dituntut untuk dapat memenuhi kebutuhan transmisi yang berkapasitas besar dengan bitrate tinggi. Salah satu teknologi yang dapat memenuhi kebutuhan tersebut adalah WiMAX 802.16e yang dapat melayani pengguna yang bergerak. Dengan kondisi pengguna yang bergerak (dapat berpindah-pindah), maka keadaan kanal yang ditempati oleh setiap pengguna akan selalu berubah setiap waktu. Dengan kondisi seperti itu, maka pengguna tidak dapat dilayani secara merata. Pengguna yang berada dekat dengan base station akan menerima layanan yang lebih baik daripada pengguna yang berada lebih jauh dari base station. Pada tugas akhir ini, membahas salah satu metode untuk mengatasi kondisi tersebut, yaitu menggunakan metode Adaptive Modulation and Coding (AMC) pada teknologi WiMAX 802.16e. teknologi ini digunakan untuk menjaga kualitas layanan agar performansi tetap terjaga. Modulasi yang digunakan adalah QPSK, 16QAM, dan 64QAM. Performansi WiMAX 802.16e akan diukur berdasarkan kondisi BER (Bit Error Rate) yang digunakan tanpa AMC, dengan AMC tipe I dan AMC tipe II.Hasil simulasi menunjukkan bahwa kinerja Adaptive Modulation and Coding tipe II lebih baik daripada AMC tipe I maupun tanpa AMC. AMC tipe II membutuhkan ±9.3 dB untuk mencapai nilai efisiensi sama dengan satu dan hanya membutuhkan ±14.7dB untuk mencapai nilai BER 10-6, lebih kecil dari AMC tipe I yang membutuhkan ±12.3 dB untuk mencapai efisiensi sama dengan satu dan ±15.1dB untuk nilai BER 10-6.Kata Kunci : WiMAX 802.16e, AMCABSTRACT: The need of wireless service currently required to meed the needs of large capacitytransmission with high bit rate. One of technology that can fulfill them is WiMAX 802.16ethat can serve moving users. With the condition of moving users (can be moved around), then the channel that occupied by each user will always change every time. With such condition, then the user can not be treated equally. Users who are close to the base station will receive better treatment and users who are located further away from the base station can be treat worse. On this thesis, we discuss a method to treat the condition, which is using the Adaptive Modulation and Coding (AMC) on 802.16e WiMAX technology. This technology is used to maintain the quality of service so that performance is maintained. Modulation used is QPSK, 16QAM, and 64QAM. WiMAX 802.16e performance will be measured based on the BER (Bit Error Rate) is used without the AMC, using AMC type I and type II. The simulation results show that the performance of Adaptive Modulation and Coding Type II is better than type I or without AMC. AMC type II needs ±9.3 dB to approach efficiency equals one and needs ±14.7dB for the target 10-6, smaller than AMC type I that needs ±12.3dB to approach efficiency equals one and needs ±15.1dB for the target 10-6Keyword: WiMAX 802.16e, AM

ANALISIS MODULASI ADAPTIF DAN CODING PADA HSDPA

ABSTRAKSI: Komunikasi wireless saat ini membutuhkan data-rate yang cukup besar untuk memenuhi kebutuhan konsumen yang terus meningkat, baik itu untuk transmisi voice, data, maupun video. Untuk itu dibutuhkan sistem komunikasi wireless yang mampu memberikan layanan dengan data-rate besar dan dengan tingkat efisiensi spektral yang tinggi salah satunya adalah dengan High-Speed Downlink Packet Access (HSDPA).HSDPA merupakan salah satu standar 3G telephony (Wideband-CDMA) yang dipublikasikan oleh 3GPP (3rd Generation Partnership Project). Untuk mengatasi kendala dalam propagasi sinyal HSDPA dilengkapi dengan Fast Retransmission dan Hybrid Automatic Repeat reQuest (HARQ) yang dapat mengirimkan kembali data yang rusak dalam proses transmisi. Selain itu untuk meningkatkan kinerja sistem HSDPA juga dilengkapi Adaptive Modulation and Coding (AMC). AMC memungkinkan sistem untuk merubah skema modulasi berdasarkan kondisi kanal radio. Tugas Akhir ini membahas tentang penggunaan Adaptive Modulation and Coding pada HSDPA menggunakan algoritma Threshold Method.Penggunaan teknik Adaptive Modulation dan Coding pada HSDPA dapat meningkatkan kinerja dan efisiensi sistem yaitu dengan mengoptimalkan kualitas sinyal trasmisi. Untuk target BER 10-4 teknik AMC memberikan perbaikan berkisar dari 0,3 dB hingga 11 dB pada variasi kecepatan user. Ketika kondisi kanal memungkinkan sistem HSDPA mampu mencapai peak data rate yaitu sebesar 3,6 Mbps.Kata Kunci : HSDPA, Adaptive Modulation and Coding, Algoritma Threshold MethodABSTRACT: Nowadays wireless communication desires high data-rate to meet up raising customer’s demands, in voice, data, and video transmission. One of the most suitable solutions to meet that condition with high spectral efficiency is High-Speed Download Packet Access (HSDPA).HSDPA is one of 3G telephony standards (Wideband-CDMA) published by 3GPP (3rd Generation Partnership Project). Fast retransmission Hybrid Automatic Repeat reQuest (HARQ), which has ability to retransmit fault data during transmission, present to overcome problems in HSDPA’s signal propagation. Besides that, Adaptive Modulation and Coding (AMC) is applied to improve performance of HSDPA’s system. AMC grants the system an ability to switch modulation scheme based on radio channel conditions. This Final Assignment investigates the usage of Adaptive Modulation and Coding on HSDPA with fixed threshold algorithm.Applied Adaptive Modulation and Coding method on HSDPA enhances system’s performance and efficiency which optimizes transmission signal’s quality. For BER target 10-4, AMC method gives improvement around 0.3 dB to 11 dB depends on its user velocity. When channel condition is in easy circumstance, HSDPA system can achive its peak rate which is 3.6 Mbps.Keyword: HSDPA, Adaptive Modulation and Coding, Algoritma Threshold Metho

Robust measurement-based buffer overflow probability estimators for QoS provisioning and traffic anomaly prediction applicationm

Suitable estimators for a class of Large Deviation approximations of rare event probabilities based on sample realizations of random processes have been proposed in our earlier work. These estimators are expressed as non-linear multi-dimensional optimization problems of a special structure. In this paper, we develop an algorithm to solve these optimization problems very efficiently based on their characteristic structure. After discussing the nature of the objective function and constraint set and their peculiarities, we provide a formal proof that the developed algorithm is guaranteed to always converge. The existence of efficient and provably convergent algorithms for solving these problems is a prerequisite for using the proposed estimators in real time problems such as call admission control, adaptive modulation and coding with QoS constraints, and traffic anomaly detection in high data rate communication networks