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Submission doc.:IEEE 802.22-07/0208r0 April. 2007 Chang-Joo Kim, ETRI Slide 1 [Ranging for WRAN system] IEEE P802.22 Wireless RANs Date: 2007-04-19 Authors: Notice: This document has been prepared to assist IEEE 802.22. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) 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 IEEEs name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEEs 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 802.22. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chairhttp://standards.ieee.org/guides/bylaws/sb-bylaws.pdf Carl R. StevensonCarl R. Stevenson as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at email@example.com@iee.org
Submission doc.:IEEE 802.22-07/0208r0 April. 2007 Chang-Joo Kim, ETRI Slide 2 Purpose This presentation provides the OFDMA ranging which will be the part of 8.9.2. Ranging in the current draft. Basically, it is based on the ranging part in the IEEE802.16. With considering the parameters of the WRAN system, we propose the method of generating the transmission symbols for initial ranging and modify the length of ranging code and the structure of ranging subchannel.
Submission doc.:IEEE 802.22-07/0208r0 April. 2007 Chang-Joo Kim, ETRI Slide 3 Ranging for WRAN Structure of transmission symbol –Initial Ranging –Periodic Ranging, Bandwidth Request and Incumbent Notification defined in the Table 37, 39 of current draft Ranging code –Using the same PRBS of 802.16 to generate the pseudorandom ranging code –Length of ranging code : 140 bits (cf. IEEE 802.16 : 144bits) Relating to the ranging subchannel Ranging subchannel –Constituted by assembling the multiple subchannels of the US –With considering the number of subcarriers per subchannel
Submission doc.:IEEE 802.22-07/0208r0 April. 2007 Chang-Joo Kim, ETRI Slide 4 Initial Ranging (1) Used for synchronizing to the BS for the first time –Be able to measure the timing offset and the transmit power level
Submission doc.:IEEE 802.22-07/0208r0 April. 2007 Chang-Joo Kim, ETRI Slide 5 Initial Ranging (2) The number of transmission symbols-1 –Relating to the TTG TTG : RTD + RF switching delay at CPE (WiBro : 9us) –Since RF switching delay is required by each CPE, the # of required symbols depends on the round trip delay –Cell coverage : 33km (typical) RTD : 220us Minimum OFDMA symbol duration is 231us. (8MHz, CP = 1/32) Two symbols are acceptable.
Submission doc.:IEEE 802.22-07/0208r0 April. 2007 Chang-Joo Kim, ETRI Slide 6 Initial Ranging (3) The number of transmission symbols-2 –Cell coverage : up to a maximum of 100km In FRD : The typical range of the system is 33 km for a coverage of population density of about 1.25 person/km2 and above, and up to a maximum of 100 km where higher base station transmit power is permitted in the relevant regulatory domains. –3 or 4 symbols may be required according to the cell coverage. –Need the flexible method to generate the transmission symbols Cell coverage RTD (us) The # of required symbols for initial ranging Min. symbol duration [ 8MHz, CP=1/32 : 231us] Max. symbol duration [ 6MHz, CP =1/4 : 373.33 us] 33km220.0022 50km333.3332 80km533.3343 100km666.6743
Submission doc.:IEEE 802.22-07/0208r0 April. 2007 Chang-Joo Kim, ETRI Slide 7 Initial Ranging (4) Generation of transmission symbols for initial ranging –Using the BPSK modulation with phase rotation in the frequency domain The amount of phase rotation is proportional to the index of subcarriers. Phase rotation make the samples in the time domain be cyclically shifted. –Can maintain the phase continuity while supporting various number of symbols By increasing l parameter in the below equation according to the symbol index –Easily performed by using the offset to the n index in the process of IFFT. –where s(n,l) is the l-th OFDMA symbol for initial ranging with the sample index n subcarrier index k. l is [ 0 ~ 3]. C k is the ranging code. R is the set of index of subcarriers within the ranging subchannel. N FFT is the size of 2K FFT, 2048. N CP is the size of the cyclic prefix (= guard interval).
Submission doc.:IEEE 802.22-07/0208r0 April. 2007 Chang-Joo Kim, ETRI Slide 8 Initial Ranging (5) Phase continuity in the red circle –Using the same ranging code for each symbol –Two consecutive OFDMA symbols –ex) three consecutive OFDMA symbols
Submission doc.:IEEE 802.22-07/0208r0 April. 2007 Chang-Joo Kim, ETRI Slide 9 Periodic Ranging/BW request/Incumbent Notification Used by CPE that have already synchronized to the BS In the case of one symbol In the case of three symbols –Using three different ranging codes
Submission doc.:IEEE 802.22-07/0208r0 April. 2007 Chang-Joo Kim, ETRI Slide 10 Ranging codes –Same PRBS as IEEE802.16 –The length of each ranging code is 140 bits. (802.16 : 144 bits) –Ranging code group (refer to the table 39 in the draft) All the ranging codes used on this upstream will be between S and ((S+N+M+L+I) mod 256), 0 <= S <= 255. –N, M, L and I is the number of initial-ranging codes, periodic-ranging codes, bandwidth-request codes and incumbent notification codes, respectively. s6:s0 = US_IDcell (s6 is the MSB of US_IDcell)
Submission doc.:IEEE 802.22-07/0208r0 April. 2007 Chang-Joo Kim, ETRI Slide 11 Performance Detection Probability and False alarm probability –802.16 : ITU - Pedestrian-B and Vehicular-B –802.22 : WRAN Profile B and C –SNR : 20dB –There is no big difference between the channel environments of two systems
Submission doc.:IEEE 802.22-07/0208r0 April. 2007 Chang-Joo Kim, ETRI Slide 12 Ranging subchannel All pilot and data subcarriers within the ranging subchannel are used for ranging transmission. Construction of one ranging subchannel –If using the 7x1 with 60 subchannels for US 5 subchannels (28 subcarriers per subchannel) used for ranging subchannel –If using the 7x1 with 120 subchannels for US 10 subchannels (14 subcarriers per subchannel) used for ranging subchannel –Two types of ranging subchannel can support the 140 bits of ranging code.
Submission doc.:IEEE 802.22-07/0208r0 April. 2007 Chang-Joo Kim, ETRI Slide 13 Conclusion Initial ranging transmission may be performed during two or three symbols. The phase continuity of the initial ranging symbols is obtained by using the simple procedure of phase rotation in the frequency domain. The length of ranging code is 140 bits. Ranging subchannel can consist of the five or ten subchannels of US. Normative text will be based on this presentation.
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