Wireless Communication

Merkebu Tekaw ¹, Dilip Mali ², Sinshaw Bekele ¹

Affiliations
1 School of Electrical and Computer Engineering, Ethiopian Institute of Technology (EiT-M) Mekelle University, Mekelle, ET
2 School of Electrical and Computer Engineering, Ethiopian Institute of Technology (EiT -M) Mekelle University, Mekelle, ET

Abstract

Most commonly cellular systems use smaller cells to handle high population of mobile users. But this solution leads to higher handoff requests which require good handoff management algorithms which give priority to handoff calls on the expense of blocking the originating calls. Guard channel based schemes are among the schemes that give priority to handoff calls. This work aims to combine the concept of time threshold and load balancing to the existing guard channel based schemes so as to decrease the dropping probability of handoff calls. The Matlab based simulation results show that the proposed systems have good performance in terms of handoff call dropping probability.

Keywords

Blocking Probability, Dropping Probability, Guard Channel Scheme, Handoff Call, New Call

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Dilip Mali ¹, Freweyni Kidane ¹, Tawatu Abreha ¹, Sinshaw Bekele ¹

Affiliations
1 Department of Electrical and Computer Engineering, EiT-M, Mekelle University, Mekelle, ET

Abstract

Smart antennas are usually employed at the base stations to radiate narrow beams to serve different users by using spatial processing. In this paper the use of adaptive antenna arrays on CDMA networks to suppress cochannel interference is carried out using newly proposed SMI-RLS algorithm which will compensate the singularity problem of SMI algorithm and minimizes the complexity of RLS algorithm. The simulation results proved that the proposed SMI-RLS algorithm is able to place deeper nulls than the other algorithms and it has minimum complexity compared to RLS algorithm.

Keywords

Interference Suppression, Smart Antennas, Adaptive Beam Forming.

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Sinshaw Bekele ¹, Dilip Mali ¹

Affiliations
1 Department of Electrical and Computer Engineering, Ethiopian Institute of Technology-Mekelle (EiT-M), Mekelle University, Mekelle, ET

Abstract

Multiuser and multi-antenna techniques are considered key to the latest mobile communication technology, which is termed as Long Term Evolution (LTE), to achieve peak user data rates. These techniques demand a precise measurement of the channel state. This study presents a review of channel estimation techniques put forward for LTE-downlink. Performance and implementation complexity of different pilot-assisted schemes such as Minimum Mean Square Error (MMSE), Least Square (LS) based channel estimation methods will be discussed in detail. Furthermore, semi-blind algorithms which make use of the data symbols in addition to the pilot tones are also presented.

Keywords

Channel Estimation, LTE, MU-MIMO, LS, LMMSE.

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