Juha Meinila

Practical aspects of using IMT-advanced channel models

A geometry-based stochastic channel model was adopted for IMT-advanced evaluations. The complexity of the channel model has been under discussion within ITU-R working groups as well as in industry and academia performing system level simulations of future B3G/4G systems. The complexity reduction is a key task to improve the model usability. However, the complexity reduction should be made without reducing the model accuracy and generality too much. The large scale propagation parameters are random variables with certain distribution. One set of large scale and small scale parameters is called a ldquodroprdquo. To obtain statistical confidence, the number of drops has to be sufficient. Also in each drop, the length of simulation should be long enough. Therefore it is necessary to investigate the required number of drops and impulse responses per drop. Even more important is to study if we need multiple drops at all. This paper presents several approximation steps from full multi-drop IMT-advanced model to simple AWGN. The main message of this paper is to introduce the different approximation steps and their impact on simulation complexity. Simplification of accurate model is always possible, and the methods are known, but doing vice versa is impossible without additional information. Another result is that average channel model is not sufficient, but multiple drops are needed. Additionally, this paper discusses practical aspects on network level simulations such as network layout, user types and penetration losses.

Effects of Noise Cut for Extraction of Wideband Channel Parameters

Effects of noise cut for extracting wideband channel parameters were investigated by 15, 20, 25, and 30 dB fixed levels, and a method of dynamic noise cut. The comparisons are given by deriving the power delay profiles (PDPs), the rms delay spread (DS), number of paths (NoPs) and Ricean K-factors based on indoor-to-outdoor wideband measurements at 5.25 GHz with RF bandwidth of 100 MHz. The conclusion is that the traditional method using fixed level noise cut is in general under estimate the DS and NoPs. K- factors are not sensitive to noise irrespective of what kind of method is applied and how deep of the fixed levels. The PDPs are not very sensitive to fixed level noise cut, however, obvious changes can be observed by dynamic noise cut. The dynamic noise cut is preferred in case of clear noise floors for the measured IRs.

A Novel Full Path-Loss Model for a Street Crossing in Urban Microcells

Based on the wideband multi-input multi-output (MIMO), channel measurements carried out in downtown Helsinki, Finland, with 11 measurement routes at 3 base station (BS) sites, a full path-loss model including transition region is developed for urban microcells with Manhattan street blocks. The carrier frequency was 5.3 GHz with 100 MHz bandwidth. The size of a transition region is about 7-10 times of the first Fresnel radius with 15-23 m street widths. The model can continuously predict the path-loss when a mobile station (MS) is turning a street crossing from the line-of-sight (LOS) to non-LOS (NLOS) routes. Moreover, the proposed path-loss model is validated by an independent measurement carried out in downtown Oulu, Finland, for urban microcells at the same carrier frequency and bandwidth. By comparison with the measurement results obtained in both Helsinki and Oulu downtowns, it is found that the proposed path-loss model in this communication is more accurate in most of the measured routes, and it is also concise and easy to be implemented for coverage prediction in urban microcells.

Indoor, Rural and Suburban Channel Models and Parameters for B3G Link and System Level Simulations

Based on the wideband measurements for indoor, rural and suburban environments at 5.25 GHz with 100 MHz bandwidth, the basic required channel parameters and models such as the rms delay spread, number of clusters, path delays, and tapped delay line models were derived for beyond 3G (B3G) wireless communications. The results derived in the paper could be the necessary models and parameters for B3G system level and link level simulations, and also for the planning B3G radio systems