cific RS sequences, has been developed. Depending on time variance of the radio channels, more or less intercell IF suppression is possible. In the 3G-LTE specification, reference symbols are intended for the purpose of intracell channel estimation; Frequency shifts sequences of length three enable the separate estimation of all three channels belonging to the sectors of the same NB. Furthermore, pilot symbols for the different transmit anten- nas are defined and located on different time and frequency positions (i.e., orthogonal in a resource block). In addition, pilots are scrambled using gold sequences (PRSs) to be defined by the network operators. Schiffermüller and Jungnickel [33] propose applying in addition block-orthogonal sequences © 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPP LTE Radio and Cellular Technology Beam forming with Distributed AEs Beam forming with 1/2 Spacing (open space) Position x/y: x/y = 40/0; 20/25.05; 20/50.1; 35/99.65 Position x/y: X = 20 y = 50, 50.05 50.1, 50.15 4 AEs, As 2 25 m 4 AEs, As = 5 cm Desired Power for MT1: Interference Power for MT1: Combining ZF; Assigned BS:1 234567 Combining ZF; Assigned BS:1234567 341.4 341.4 341.3 341.3 341.2 341.2 341.1 341.1 340.9 340.9 340.8 340.8 340.7 340.7 340.6 340.6 340.5 340.5 Signal, MRC IF notch, ZF X Coordinate (meter) X Coordinate (meter) Figure 7.16 Far-field beam-forming pattern: (a) for central and distributed AEs; (b) for MRC versus ZF IF notches. (e.g., Hadamard sequences) HS spread over the time domain from slot to slot with a maximum sequence length of 16. Definition 7.2 (Block-Orthogonal Sequence) Each row of a block-orthogonal sequence matrix HS is orthogonal to all other rows of the same matrix with full correlation length (i.e., CCH = I). Reducing the correlation length to n yields a matrix with block-wise orthogonal properties, where each block is of size nxn. Furthermore, each nth row should be identical for a given correlation length N. Figure 7.18 visualizes the suggested pilot grid, where the number (h