1. Interference Mitigation Performance with 4 antenna BS IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number: IEEE S802.16m-08/005 Date Submitted: 2008-01-17 Source: Michael Erlihson, michaele@runcom.co.ilmichaele@runcom.co.il Doron Ezri dorone@runcom.co.ildorone@runcom.co.il Runcom Technologies Moshe Levi St. 11, Rishon LeZion 75658, Israel * http://standards.ieee.org/faqs/affiliationFAQ.html Venue: Call for Contributions on Project 802.16m System Description Document (SDD) - IEEE 802.16m-07/047, specifically, changes to the 802.16m reference model. Base Contribution: IEEE P802.16m-08/005 Purpose: To incorporate the requirement of placing of at least 4 Rx antennas at the BS. Notice: This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.16. Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and.http://standards.ieee.org/guides/bylaws/sect6-7.html#6http://standards.ieee.org/guides/opman/sect6.html#6.3 Further information is located at and.http://standards.ieee.org/board/pat/pat-material.htmlhttp://standards.ieee.org/board/pat

2. Outline: Motivation Mathematical model Simulation Results Conclusions Text Changes

3. Motivation: According to the requirements of 802.16m, high data rates shall be in difficult conditions, e.g. in the presence of a strong interference. Thus the standard supports advanced antenna techniques, for example such as Rx beamforming (Rx BF). Since in many of the deployment scenarios envisioned for 802.16m, the system performance is limited by interference (e.g. inter-cell interference), Rx BF techniques are likely to play a major role.

4. Examined scenarios: PUSC UL w/o Subchannel rotation. symbols (time) subcarriers (frequency)‏ data subcarrier pilot subcarrier This transmission format is applied here since it allows a large density of pilots in a relatively small frequency band. This allows the generation of a weight vector designed for a band as small as 4 SCs.

5. Mathematical model Denote by the channel from the desirable source and by the signal from the desirable source. We also assume the presence M of sources of interference.Thus, the mathematical model for the received signal is: where is the channel of the i-th interference source and is an additive white Gaussian noise (AWGN) with unit power.

6. Mathematical model: We define the signal to interference ratio (SIR), the signal to noise ratio (SNR) and the signal to interference and noise ratio (SINR) as follows: where is the channel power of the desirable user, is the channel power of i-th interferer and is the noise intensity.

7. Ranging: Ranging codes are transmitted from the user to the BS in order to obtain information on the network set-up and synchronize the link. In particular, ranging is used to obtain the information about the user presence (user RNG sequence detection) and also for the time synchronization (user timing offset calculation).

8. Simulation parameters: ITU benchmark Pedestrian B 3 km/h and Vehicular A 60km/h channels. The correlation between users' user’s channels is 0.5 or zero (the correlation is assumed real valued). The interference channels are assumed uncorrelated with the desirable user channels. RNG sequence length=144 subcarriers. Convolutional Turbo Coding, FEC block size=480bits, QPSK 1/2, Carrier frequency=2.5GHz.

9. Simulation results: Ranging Number of Rx antennas effect, Ped. B 3km/h; No correlation.

10. Simulation results: Ranging SIR effect; Ped. B 3km/h; no correlation,SIR=-10dB

11. Simulation results: Ranging Correlation effect; SIR=-10dB, Ped. B 3km/h;

12. Simulation results: Ranging Channel effect; SIR=-10dB, no correlation

13. Simulation results: Rx BF on UL Data MRC 1X4 versus Rx BF, SIR=-10dB, zero correlation, Ped. B 3km/h.

14. Simulation results: Rx BF on UL Data SIR effect; Correlation=0.5, Pedestrian B 3km/h.

15. Simulation results: Rx BF on UL Data Correlation effect; SIR=-10dB, Pedestrian B 3km/h.

16. Simulation results: Rx BF on UL Data Rx BF for various channel models; SIR=-10dB, correlation=0.5.

17. Conclusions: BF algorithms provide significant performance gains in the case of strong interference for the ranging signals and for UL data. The scenarios of extremely strong interference where chosen to demonstrate the resilience of BF methods to interference in various transmission methods (not necessarily narrow band signals as PUSC w/o Subchannel rotation). Since Rx BF methods require larger number of antennas at the BS, we believe 4 antennas at the BS should be a starting point for the 16m.

18. Text Changes Include a Receive Beamforming section in the SDD: Receive Beamforming The system shall support receive beamforming techniques at the BS. The minimum number of antennas for receiver beamforming at the BS shall be four.