2007年5月25日 星期五
Technology Review: Mapping Traffic Flow
Technology Review: Mapping Traffic FlowThe software determines the average speed of roadways across the United States based on two years of historical traffic-speed data collected from commercial fleet vehicles; it uses real-time global positioning software and road sensors from the department of transportation.
2007年5月18日 星期五
HP Lab's Location-Based Project :MSCAPE
MSCAPERS
HP Lab launch a project exploring the Location-Based games and city walking tours.
HP Lab launch a project exploring the Location-Based games and city walking tours.
2007年5月17日 星期四
Comparision between AAS and MIMO
The view graph showed above is the summary based on the Nortel's white paper: MIMO or AAS: Key Technology choice in deploying WiMAX.
Unstrung - WiMax/Broadband Wireless - BT Wants WiMax - Wireless News Analysis
Unstrung - WiMax/Broadband Wireless - BT Wants WiMax - Wireless News Analysis
"If the auction gets too aggressive we don't have to play -- we have learned from our past experience. If the price is right, then that's fine. If the price is too high then the MVNO opportunity is the other option," BT Wholesale CTO Matt Beal said
"If the auction gets too aggressive we don't have to play -- we have learned from our past experience. If the price is right, then that's fine. If the price is too high then the MVNO opportunity is the other option," BT Wholesale CTO Matt Beal said
2007年5月16日 星期三
Multicast and Broadcast Services in Mobile WiMAX
Multicast and Broadcast Service (MBS) is defined as an interoperability feature (IO-MBS) by WiMAX Forum and will be tested in Wave 2. MAC and Physical layer related to MBS already defined in IEEE802.16e. Hence, the implementation between MS and BS is more clear. Currently, WiMAX forum not yet define the interface between MBS server and ASN GW but some common industry implementation methodology can be done by vendor.
ASN GW can be a proxy for multicast and broadcast just like an multicast router in IP world. When the MS need to receive multicast service, an IGMP join message for a specific multicast channel will be sent to ASN GW. After some authorization procedure, ASN GW will notify BS to setup multicast channel with the requesting MS through DSA messages which is defined in 802.16. After DSA procedure, MS can receive the multicast channel information from MBS_MAP. Before MS terminate the multicast reception, an IGMP leave message will be sent to AGW. Broadcast service can also be acquired through DSA process and MBS_MAP but bypass the IGMP process.
Mobility function of MBS service can be supported through MBS zone. When the MS moving in the BS culster within the same MBS zone, there is no need to setup new connection ID.
read more ...
Channel Coding and Modulation Required by WiMAX Forum and IEEE 802.16e
Although the Convolution Turbo Code (CTC) is optional in 802.16e, yet both of the Convolution Code(CC) and Convolution Turbo Code(CTC)are required to be implemented in BS and MS according to WiMAX forum's Mobile WiMAX System Profile Release 1 and will be tested in Wave 1. 64-QAM in uplink direction is optional in 802.16e and WiMAX forum's System Profile.
2007年5月15日 星期二
Mandatory Modulation and Coding Rate in Fixed WiMAX OFDM mode
The coding scheme of Reed-Solomon (RS) error correction code can be denoted as (n, k, T), where
n is the number of overall bytes after encoding,
k is the number of data bytes before encoding,
T is the number of data bytes which can be corrected. From the property of RS code, T=(n – k )/2.
The encoding is performed first passing the data in block format through the RS encoder and then passing it through the convolutional code (CC) encoder. Hence,
Coded block size = (the number of overall bytes after RS encoding) / CC code rate
IEEE 802.16-2004 OFDM mode require that the RS-CC overall encoding rate 1/2 should be used as the coding mode when requesting access the network (except in subchannelization modes, which use only convolution code 1/2 and bypass RS code)and in FCH burst.
For example in 16-QAM modulation using RS code (64, 48, 4), the number of overall bytes after RS encoding is 64. And then using CC code rate 2/3, the resulting coded block size is 64*(2/3) ie.96 which is also resulting the overall coding rate 1/2 (ie. 48/96).
2007年5月10日 星期四
Unstrung - WiMax/Broadband Wireless - Sprint Goes Femto With WiMax - Wireless News Analysis
Unstrung - WiMax/Broadband Wireless - Sprint Goes Femto With WiMax - Wireless News Analysis
Femtocell fullfill the coverage at indoors and in-building. Also possible to provide FMC(fixed mobile convergence)service.
picoChip Design Ltd. provide WiMAX reference design using picoArray for total WiMAX MAC and PHY solution including Femtocell of 802.16e OFDMA WiMAX.
The picoChip's WiMAX solution is committed to supporting the standards roadmap and providing customers with a seamless upgrade path to new capabilities, including AAS, MIMO and .16j mobile relay.
Femtocell fullfill the coverage at indoors and in-building. Also possible to provide FMC(fixed mobile convergence)service.
picoChip Design Ltd. provide WiMAX reference design using picoArray for total WiMAX MAC and PHY solution including Femtocell of 802.16e OFDMA WiMAX.
The picoChip's WiMAX solution is committed to supporting the standards roadmap and providing customers with a seamless upgrade path to new capabilities, including AAS, MIMO and .16j mobile relay.
2007年5月7日 星期一
Scalable OFDMA selected by WiMax Forum
在802.16-2005 section 8.4.2.3中規定Channel Bandwidth與sampling factor之間的關係, 由Channel Bandwidth(BW), number of used sub-carrier(Nused)與sampling factor可決定sub-carrier spacing, 在相同的sampling factor之下, sub-carrier spacing是固定的
WiMAX forum 為了提高設備實作時的互連性, 特別依據802.16-2004及802.16-2005再明確規範出各項必要及選項功能, 完整描述於WiMAX_Forum_Mobile_System_Profile Release 1.0的文件中,
OFDMA with TDD是System Profile Release 1的基本要求, 台灣選用2.5GHz屬於WiMAX forum定義的2.496GHz~2.69GHz Band Class 3, 移動台MS必須支援整個Band Class的frequency range, 基站台BS則可依BS Vendor宣告支援特定Band Class的部分frequecy range, 但至少需支援到最大channel bandwidth的3倍
Channel Bandwidth為1.25MHz, 5MHz, 10MHz, 20MHz時, 皆為1.25Hz的倍數, 查表得sampling factor n=28/25
Channel Bandwidth為1.75MHz, 7MHz, 8.75MHz時, 皆為1.75MHz的倍數, 查表得sampling factor n=8/7
在802.16-2004 Section 8.4.2.4提到sampling frequency Fs=floor(n*BW/8000)*8000
BW為5MHz的sampling frequency Fs=floor((28/25)*5/8000)*8000=5.6MHz
BW為10MHz的sampling frequency Fs=floor((28/25)*10/8000)*8000=11.2MHz
又sub-carrier frequency spacing可由此推算 deltaF=Fs/Nfft
所以在保持sub-carrier frequency spacing不變的條件下, 只要變動FFT size即可支援不同的channel bandwidth具OFDMA功能, 也就是scalable OFDMA
BW為5MHz若使用Nfft=512, 則BW為10MHz時, Nfft=1024, 而sub-carrier frequency spacing皆維持為deltaF=5.6/512=10.94kHz
Useful symbol time Tb= 1/deltaF, 所以BW為5MHz及10MHz的useful symbol time Tb=1/10.94=91.4usec
在Mobile WiMAX System Profile release 1的section 4.1.1.4中選定cyclic prefix(CP)的必要項目為1/8, 以保護傳送中因multipath fading造成的影響, 所以Guard Time Tg=Tb/8=91.4/8=11.4usec, 加上cyclic prefix 以後的OFDMA symbol duration Ts=Tb+Tg=91.4+11.4=102.9usec, 以Mobile WiMAX System Profile release 1的section 4.1.1.5規定frame length的必要項目為5ms, 因此一個frame可以有5/0.129=48個OFDMA symbol
The guard time can protect the multipath delay spread whose delay time is smaller than guard time. The common pratice about the delay spread in home is 50nsec and the delay spread in outdoors is 300nsec. The guard time in WiMAX is much larger than those common pratice delay spread values.
公式摘要:
Nused= number of used sub-carrier
Nfft= smallest power of 2 greater than Nused
Sampling Frequency Fs=floor(n*BW/8000)*8000
Sub-carrier frequency spacing deltaF=Fs/Nfft
Useful symbol time Tb=1/deltaF
Guard Time Tg=Tb*CP
OFDMA symbol duration Ts=Tb+Tg
使用OFDMA時, 當channel bandwidth變大時只要改變FFT size, 仍可維持相同的Sub-carrier frequency spacing及OFDMA symbol time
In other words, the basic principles of Scalable OFDMA are outlined as:
WiMAX forum 為了提高設備實作時的互連性, 特別依據802.16-2004及802.16-2005再明確規範出各項必要及選項功能, 完整描述於WiMAX_Forum_Mobile_System_Profile Release 1.0的文件中,
OFDMA with TDD是System Profile Release 1的基本要求, 台灣選用2.5GHz屬於WiMAX forum定義的2.496GHz~2.69GHz Band Class 3, 移動台MS必須支援整個Band Class的frequency range, 基站台BS則可依BS Vendor宣告支援特定Band Class的部分frequecy range, 但至少需支援到最大channel bandwidth的3倍
Channel Bandwidth為1.25MHz, 5MHz, 10MHz, 20MHz時, 皆為1.25Hz的倍數, 查表得sampling factor n=28/25
Channel Bandwidth為1.75MHz, 7MHz, 8.75MHz時, 皆為1.75MHz的倍數, 查表得sampling factor n=8/7
在802.16-2004 Section 8.4.2.4提到sampling frequency Fs=floor(n*BW/8000)*8000
BW為5MHz的sampling frequency Fs=floor((28/25)*5/8000)*8000=5.6MHz
BW為10MHz的sampling frequency Fs=floor((28/25)*10/8000)*8000=11.2MHz
又sub-carrier frequency spacing可由此推算 deltaF=Fs/Nfft
所以在保持sub-carrier frequency spacing不變的條件下, 只要變動FFT size即可支援不同的channel bandwidth具OFDMA功能, 也就是scalable OFDMA
BW為5MHz若使用Nfft=512, 則BW為10MHz時, Nfft=1024, 而sub-carrier frequency spacing皆維持為deltaF=5.6/512=10.94kHz
Useful symbol time Tb= 1/deltaF, 所以BW為5MHz及10MHz的useful symbol time Tb=1/10.94=91.4usec
在Mobile WiMAX System Profile release 1的section 4.1.1.4中選定cyclic prefix(CP)的必要項目為1/8, 以保護傳送中因multipath fading造成的影響, 所以Guard Time Tg=Tb/8=91.4/8=11.4usec, 加上cyclic prefix 以後的OFDMA symbol duration Ts=Tb+Tg=91.4+11.4=102.9usec, 以Mobile WiMAX System Profile release 1的section 4.1.1.5規定frame length的必要項目為5ms, 因此一個frame可以有5/0.129=48個OFDMA symbol
The guard time can protect the multipath delay spread whose delay time is smaller than guard time. The common pratice about the delay spread in home is 50nsec and the delay spread in outdoors is 300nsec. The guard time in WiMAX is much larger than those common pratice delay spread values.
公式摘要:
Nused= number of used sub-carrier
Nfft= smallest power of 2 greater than Nused
Sampling Frequency Fs=floor(n*BW/8000)*8000
Sub-carrier frequency spacing deltaF=Fs/Nfft
Useful symbol time Tb=1/deltaF
Guard Time Tg=Tb*CP
OFDMA symbol duration Ts=Tb+Tg
使用OFDMA時, 當channel bandwidth變大時只要改變FFT size, 仍可維持相同的Sub-carrier frequency spacing及OFDMA symbol time
In other words, the basic principles of Scalable OFDMA are outlined as:
[1]Sub-carrier spacing is independent of channel bandwidth
[2]The number of sub-carrier scales with channel bandwidth
[3]The smallest unit of bandwidth allocation, based on the concept of subchannels, is fixed and indepedent of bandwidth and other modes of operation.
[4]The number of subchannels scales with bandwidth and the capacity of each individual subchannel remains constant.
Testing Waves of WiMax
WiMAX forum defines waves and releases for certification work of WiMax.
The 3 testing waves of fixed WiMax IEEE 802.16-2004 including: Wave 1 Air protocol interoperability, Wave 2 Outdoor CPE, QoS, Security, Wave 3 indoor CPE, PC cards, nomadic service .
The 4 testing waves of mobile WiMax IEEE 802.16-2005 including: Wave 1 Air protocol interoperability, Wave 2 CPE, QoS, Wave 3 Handoff, Simple mobility, Wave 4 full mobility. The planned schedule for wave 1 of mobile wimax will be in 1st half of 2007. Wave 2 certification will not happen until 2nd half of 2007.
New added mandatory test items for wave 2 of mobile wimax including: handover, QoS, power saving, Ipv6. New added mandatory MS test items for wave 2 of mobile wimax also including: (2x2)MIMO, Beamforming, MBS(Multicast Broadcast Service). It may happen for wave 2 plugfest test in 23-27 October at Taipei.
In the document of WiMAX forum's Mobile WiMAx System Profile Release 1 section 3.3.5,
MIMO, Beamforming, MBS, ETHx are all interoperability features. Four interoperability feature groups are defined as IO-MIMO, IO-BF, IO-MBS, IO-ETHx. Those which pass the test of the interoperability feature groups will be certified with the "WiMAX Certified with NNNN capability" label.
Wave 1 test of Mobile WiMAX will be delayed to 2007 June or July. Wave 2 test will be delayed to 2007/12 or 2008/1
The 3 testing waves of fixed WiMax IEEE 802.16-2004 including: Wave 1 Air protocol interoperability, Wave 2 Outdoor CPE, QoS, Security, Wave 3 indoor CPE, PC cards, nomadic service .
The 4 testing waves of mobile WiMax IEEE 802.16-2005 including: Wave 1 Air protocol interoperability, Wave 2 CPE, QoS, Wave 3 Handoff, Simple mobility, Wave 4 full mobility. The planned schedule for wave 1 of mobile wimax will be in 1st half of 2007. Wave 2 certification will not happen until 2nd half of 2007.
New added mandatory test items for wave 2 of mobile wimax including: handover, QoS, power saving, Ipv6. New added mandatory MS test items for wave 2 of mobile wimax also including: (2x2)MIMO, Beamforming, MBS(Multicast Broadcast Service). It may happen for wave 2 plugfest test in 23-27 October at Taipei.
In the document of WiMAX forum's Mobile WiMAx System Profile Release 1 section 3.3.5,
MIMO, Beamforming, MBS, ETHx are all interoperability features. Four interoperability feature groups are defined as IO-MIMO, IO-BF, IO-MBS, IO-ETHx. Those which pass the test of the interoperability feature groups will be certified with the "WiMAX Certified with NNNN capability" label.
Wave 1 test of Mobile WiMAX will be delayed to 2007 June or July. Wave 2 test will be delayed to 2007/12 or 2008/1
Unstrung - WiMax/Broadband Wireless - AT&T Looking at WiMax for Video - Wireless News Analysis
Unstrung - WiMax/Broadband Wireless - AT&T Looking at WiMax for Video - Wireless News Analysis
Wave 3 WiMax Profile with 4*4 MIMO may happen in 2010.
Wave 3 WiMax Profile with 4*4 MIMO may happen in 2010.
聯合新聞網 | 財經產業 | 科技產業 | WiMAX釋照 11家搶兩張
聯合新聞網 | 財經產業 | 科技產業 | WiMAX釋照 11家搶兩張中華電信、台灣大哥大、遠傳電信、東訊、泛亞、和信、華聯國際商務、寰宇通、威達有線電視、大同、威寶、聯合通科技、亞太固網及大眾電信, 其中泛亞、和信分別屬於台哥大、遠傳集團，兩家的申請資格是否通過，將再進行審查
CHT
TCC +泛亞
FETnet + 和信
Vibo + 東訊
大同 + 大眾
亞固,
威達有線, 聯合通, 寰宇通, 華聯國際
CHT
TCC +泛亞
FETnet + 和信
Vibo + 東訊
大同 + 大眾
亞固,
威達有線, 聯合通, 寰宇通, 華聯國際
2007年5月6日 星期日
WIMAX系统中的多天线技术及应用 - 技术探讨 - WiMAX - 通信世界网
WIMAX系统中的多天线技术及应用 - 技术探讨 - WiMAX - 通信世界网This document will discuss the MIMO technology including AAS, STC etc which are defined as optional technology in IEEE 802.16e.
2007年5月1日 星期二
Downlink and Uplink path of WiMax BS for OFDMA part
Scalable OFDMA的設計主要由OFDM核心以及傳送與接收Subchannelization等兩個部分所構成。
OFDM核心控管FFT
OFDM核心控管FFT運算與Cyclic Prefix的附加與移除，FFT的大小是一個參數，必須在設計時進行指定。
‧下行傳送
下行OFDM核心模組執行Frequency Domain輸入資料的IFFT，並增加Cyclic Prefix到產生的Time Domain資料之上。Cyclic Prefix附加模組包含一個控制器，可以做為從FFT輸出封包的緩衝區，並增加相對於輸出封包開端一樣的內容到輸出封包的結尾之上，如此一來將需要非常大的記憶體資源，如果數據機在TDD模式下運作時，其中的嵌入式記憶體可以跟上行OFDM核心共享。
‧上行接收
上行OFDM核心模組執行Time Domain輸入資料的FFT作業，並移除Cyclic Prefix，必須提供同步化訊號以指定Cyclic Prefix的起點，移除Cyclic Prefix模塊會在Cyclic Prefix期間忽略資料，並將剩餘的Sampling 寫入到FFT輸入緩衝區中。
當Channel特性變更之後，在Cyclic Prefix時間的起點之後，便可能不會一直有同步脈衝，這個硬體必須被設計來處理這種狀況，但是脈衝的變化程度將被限制在Cyclic Prefix的時間之內，且起始脈衝將不會在Preamble Symbol完全被Phase Lock前出現。
Subchannelization及產生Pilot
Frequency Domain所代表的資料是由控制模組所構成，用以產生相對應的RAM儲存模組的讀取與寫入位址。未處理的輸入時槽將放在記憶體模組中，並透過跨越Frequency Domain的方式來分配資料樣本，用次通道化模組來構成OFDMA符號，並產生必須的引導與保護載波。
FFT的大小必須在合成時進行設置，但是在運作模式(FUSC/PUSC)與IDCell的值可以在執行時進行設置，在PUSC模式下，至少需要有兩個資料符號傳送到緩衝區，在這個模式中，兩個符號將必須同時被構成。
Desubchannelization取得資料Slot
解次通道化模組將執行以下的處理程序，以便從接收到的OFDMA符號中萃取出資料時槽：
．重新整理所接收的副載波，並從FFT巨集核心功能中組成OFDMA符號。
．萃取出Null Subcarrier與Pilot Subcarrier。
．輸出每個資料Slot。
OFDM核心控管FFT
OFDM核心控管FFT運算與Cyclic Prefix的附加與移除，FFT的大小是一個參數，必須在設計時進行指定。
‧下行傳送
下行OFDM核心模組執行Frequency Domain輸入資料的IFFT，並增加Cyclic Prefix到產生的Time Domain資料之上。Cyclic Prefix附加模組包含一個控制器，可以做為從FFT輸出封包的緩衝區，並增加相對於輸出封包開端一樣的內容到輸出封包的結尾之上，如此一來將需要非常大的記憶體資源，如果數據機在TDD模式下運作時，其中的嵌入式記憶體可以跟上行OFDM核心共享。
‧上行接收
上行OFDM核心模組執行Time Domain輸入資料的FFT作業，並移除Cyclic Prefix，必須提供同步化訊號以指定Cyclic Prefix的起點，移除Cyclic Prefix模塊會在Cyclic Prefix期間忽略資料，並將剩餘的Sampling 寫入到FFT輸入緩衝區中。
當Channel特性變更之後，在Cyclic Prefix時間的起點之後，便可能不會一直有同步脈衝，這個硬體必須被設計來處理這種狀況，但是脈衝的變化程度將被限制在Cyclic Prefix的時間之內，且起始脈衝將不會在Preamble Symbol完全被Phase Lock前出現。
Subchannelization及產生Pilot
Frequency Domain所代表的資料是由控制模組所構成，用以產生相對應的RAM儲存模組的讀取與寫入位址。未處理的輸入時槽將放在記憶體模組中，並透過跨越Frequency Domain的方式來分配資料樣本，用次通道化模組來構成OFDMA符號，並產生必須的引導與保護載波。
FFT的大小必須在合成時進行設置，但是在運作模式(FUSC/PUSC)與IDCell的值可以在執行時進行設置，在PUSC模式下，至少需要有兩個資料符號傳送到緩衝區，在這個模式中，兩個符號將必須同時被構成。
Desubchannelization取得資料Slot
解次通道化模組將執行以下的處理程序，以便從接收到的OFDMA符號中萃取出資料時槽：
．重新整理所接收的副載波，並從FFT巨集核心功能中組成OFDMA符號。
．萃取出Null Subcarrier與Pilot Subcarrier。
．輸出每個資料Slot。
Source: Altera
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