Tx and Rx are further departed therefore the antennas have to be placed on the chassis roof, type 2 is favorable if the propagation distance is limited whereas type 1 shows more advantage over a longer range. This selection is based on 2 considerations: 1) a shorter distance results in less free space propagation loss and therefore allows for additional reflection loss, 2) the elevation of path type 2 deviates from the horizontal direction more significantly with a shorter horizontal direction, therefore a vertically directive antenna would cause less interference on the horizontal LoS paths (because all the chassis have the identical size). We make the general suggestion that if the AoD/AoA elevation is at least 2 times the antenna Half Power Beam Width (HPBW) in the vertical direction away from the horizontal direction, type 2 has an advantage over type 1. The criterion should be adapted for every concrete scenario. Stochastic Channel Modelling The stochastic channel modelling is based on massive ray tracing simulations. We choose a Tx position in the room corner (Tx 1) and in the room center (Tx 2) for propagation path type 1/2. For path type 3, we selected Tx and Rx positions randomly on identical or adjacent chassis. Based on the simulation results, we derive a stochastic channel model in the following approach: Determine number of propagation paths. Assign a to each propagation path. Determine the pathloss of each propagation path according to its delay. Define the angular difference of each NLoS path to the LoS path. Generate uniformly distributed phase for each path. Generate frequency dispersion for each path. In the following sections, we will explain the process step by step to obtain the stochastic channel model. Path Numbers is always 1 LoS path. The empirical distributions of the numbers of NLoS paths are presented in . Table NLoS Path number distributions Type 1/2, Tx 1 Number of paths 17 18 19 20 21 Probability (%) 27 35 22 15 1 Type 1/2, Tx 2 Number of paths 16 17 18 19 20 21 Probability (%) 32 29 12 16 8 3 Type 3 Number of paths 3 4 5 6 7 8 9 11 0 Probability (%) 22 8 8 8 6 3
Tx and Rx are further departed therefore the antennas have to be placed on the chassis roof, type 2 is favorable if the propagation distance is limited whereas type 1 shows more advantage over a longer range. This selection is based on 2 considerations: 1) a shorter distance results in less free space propagation loss and therefore allows for additional reflection loss, 2) the elevation of path type 2 deviates from the horizontal direction more significantly with a shorter horizontal direction, therefore a vertically directive antenna would cause less interference on the horizontal LoS paths (because all the chassis have the identical size). We make the general suggestion that if the AoD/AoA elevation is at least 2 times the antenna Half Power Beam Width (HPBW) in the vertical direction away from the horizontal direction, type 2 has an advantage over type 1. The criterion should be adapted for every concrete scenario. Stochastic Channel Modelling The stochastic channel modelling is based on massive ray tracing simulations. We choose a Tx position in the room corner (Tx 1) and in the room center (Tx 2) for propagation path type 1/2. For path type 3, we selected Tx and Rx positions randomly on identical or adjacent chassis. Based on the simulation results, we derive a stochastic channel model in the following approach: Determine number of propagation paths. Assign a to each propagation path. Determine the pathloss of each propagation path according to its delay. Define the angular difference of each NLoS path to the LoS path. Generate uniformly distributed phase for each path. Generate frequency dispersion for each path. In the following sections, we will explain the process step by step to obtain the stochastic channel model. Path Numbers is always 1 LoS path. The empirical distributions of the numbers of NLoS paths are presented in . Table NLoS Path number distributions Type 1/2, Tx 1 Number of paths 17 18 19 20 21 Probability (%) 27 35 22 15 1 Type 1/2, Tx 2 Number of paths 16 17 18 19 20 21 Probability (%) 32 29 12 16 8 3 Type 3 Number of paths 3 4 5 6 7 8 9 11 Probability (%) 22 8 8 8 6 3 0
15-14-0310-13-003d-channel-modeling-document.docx