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Transcript of LTE
In this case the number of users was varied while the bandwidth was fixed to 5 MHz Reference table that contains the CQI index, the modulation scheme and channel coding rate corresponding to the CQI value Reference Symbols (Signals) Multiple access: uses OFDMA in the downlink and SC-FDMA in the uplink.
Data rates: 100 Mbits/s in the downlink and 50 Mbits/s in the uplink.
Throughput: in the downlink the average user throughput per MHz is 3 to 4 times higher than the previous versions and in the Uplink the average user throughput per MHz is about 2 to 3 times.
Bandwidth: Ranges from 1.4 to 20 MHz Features of LTE Extra parameters can be added such as cell throughput, channel type, and channel capacity to evaluate the performance of the system. Future Work The results also showed that in both scheduling algorithms :
The throughput decreases as the number of users in the network increase while keeping the bandwidth fixed .
The throughput increases as the bandwidth increases while keeping the number of users fixed. The results showed that the throughput in the Best CQI algorithm was higher than the throughput in the Round Robin (RR) algorithm since the resource blocks are allocated to users with the best CQI Round Robin scheduling is the guaranty of fairness for all users, and it is easy to implement.
The Best CQI scheduling maximizes the throughput by scheduling the user with the best channel quality.
. Conclusion Distribution of RB and Throughput when a Bandwidth of (10MHz) was used Distribution of RB and Throughput when a Bandwidth of (5 MHz) was used Distribution of RB and Throughput for 10 Users Distribution of RB and Throughput for Five Users Distribution of RB and Throughput when a Bandwidth of (10 MHz) was used Distribution of RB and Throughput when a Bandwidth of (5 MHz) was used Distribution of RB and Throughput for Five Users Simulation Environment Two scheduling algorithms (Round Robin and Best CQI) were simulated on a MATLAB-based LTE Downlink Level simulator.
Methodology In LTE, there are 15 different CQI values ranging from 1 to 15, depending on the value of SNR.
Scheduling Algorithms Two scheduling algorithms were suggested in this thesis, the Round Robin Scheduling and the Best Channel Quality Indicator Scheduling (Best CQI). The limited resources to transmit.
Sharing the available resources efficiently while trying not to interfere. Problem Statement The radio resource block can be seen as a frequency-time grid.
Frequency domain is divided into sub-carriers where each sub-carrier spans 15 KHz. Each sub-band consist of 12 sub-carriers.
Time domain can be divided into slots which has a duration of 0.5ms. Each sub-frame consists of 2 time slots and each frame consist on 10 sub-frame. Resource Block Long Term Evolution (LTE) is a wireless broadband technology developed by the Third Generation Partnership Project (3GPP). Introduction Introduction
Results and Discussion
Conclusion and Future Work Agenda Distribution of RB and Throughput when a Bandwidth of (15 MHz) was used Distribution of RB and Throughput when a Bandwidth of (3MHz) was used Distribution of RB and Throughput when a Bandwidth of (15 MHz) was used Distribution of RB and Throughput when a Bandwidth of (3 MHz) was used
In this case the bandwidth was varied while the number of users was fixed to 10 users Distribution of RB and Throughput for 20 Users Distribution of RB and Throughput for 10 Users
Distribution of RB and Throughput for Single User T subframe = 1ms. N data bits: data to be sent.
24: Cyclic Redundancy Check (CRC). The LTE physical layer supports different bandwidths from 1.4 MHz to 20 MHz with subcarrier spacing of 15 kHz. If UE report high CQI even when the real channel quality is poor? In this case, the network would send a large transport block size according to the CQI value and it would become highly probable that UE failed to decode it. The UE send a NACK to network where it has to retransmit it How it works ? The Best CQI scheduling assigns the resource blocks to the user with the best CQI. Best (CQI) Scheduling How it Works ? To share the available resources efficiently, scheduling algorithms were used.
Proposed Solution LTE Architecture
DownLink Scheduling Algorithms
In Long Term Evolution Distribution of RB and Throughput for 20 Users N coded bits: data plus redundant bits.
Modulation order: 2, 4 or 6.
Assigned RB: no of RB in bandwidth
Ns_RB: number of symbols per RB = 84
Total no refsym: reference symbols = 4
Sync symbols: synchronization symbols.
CHsyms: Channel Symbol Equations used to plot the throughput In this case the bandwidth was varied while the number of users was fixed to 10 users. Distribution of RB and Throughput when a Bandwidth of (1.4MHz) was used Case 2: Bandwidth used Varied Distribution of RB and Throughput for Single User In this case the number of users was varied while the bandwidth was fixed to 5 MHz Case 1: Number of Users Varied Result and Discussion Nrb= no of resource block.
Resource Block Size = 180 KHz. Case 2: Bandwidth used Varied Distribution of RB and Throughput when a Bandwidth of (1.4 MHz) was used Round Robin Scheduling Prepared by:
1. Amal Hashim Ahmed.
2. Reem Abd elaziz Mahmoud.
3. Walaa Salah Aldeen khidir.
4. Wishah Osman Amin Ismail.
Dr. Jacqueline.J.George If the network sends a large transport block even though UE reports low CQI, it is highly probable that the UE failed to decode it. The UE send a Negative Acknowledge (NACK) to the network where it has to retransmit it. Scenario 1: Round Robin Algorithm Case 1: Number of Users Varied Scenario 2: Best CQI algorithm where where where where Thanks For
Your Attention The work done in this project covers two of the downlink scheduling algorithms (RR and Best CQI). This can be extended to include other scheduling algorithms.