2007年12月29日 星期六

Homework 12-22-2007

1. Compare the business models of Metropolitan Wi-Fi Networks in the world.
Comment:
1. Seoul, South Korea :
Koreans have a fascination with PC gaming unlike any other country in the world. In South Korea, there are multiple television channels dedicated solely to broadcasting the day's video game events. Talented video game players are treated like celebrities similar to famous basketball players in the United States. At the center of all of the gaming is Seoul, which has played an important part in expanding Internet usage throughout all of South Korea.

Internet access in Seoul is extremely cheap, averaging around $20 per month for a 10Mpbs connection -- that's more than 4 times as fast and half the price of the average broadband connection in the United States. Some areas of Seoul boast commercial Internet speeds of more than 100Mbps for merely $30 per month. With speeds that fast it would only take you 5 minutes to download a two-hour high definition movie.

Seoul's current expansion plans include a $439 million project to add wireless Internet access to the subway trains. "The plan would be to create a wifi network, and then charge roughly $20 per month for access."

With such a huge broadband presence and a dedication to offering cheap, fast Internet solutions, Seoul is the definition of wired.

2. Taipei, Taiwan:

For a mere $70 million, Q-Ware Corp. was able to build a wireless network consisting of more than 20,000 access points with enough range to provide service for 90 percent of Taipei's population. That number is remarkable considering Taipei has more than 2.6 million residents in a 105 square mile area. Access to the city wide WiFi network is available for a low monthly fee ranging from $4.50 to $12.

Perhaps the biggest benefit of having city wide WiFi comes in the form of a near-ubiquitous Internet access. Users no longer have to find Internet cafés or wait until they get home to receive stock updates or check email on their laptops. Instead, anyone can simply activate a WiFi enabled device and enjoy -- pending they have purchased the service from Q-Ware Corp. of course.

To go along with the WiFi project, Ying-jeou Ma has implemented several types of free web services for the city's inhabitants including lifetime email accounts, ability to pay for city service bills online and a "three-hour online training course for Taipei citizens to acquire and sharpen their Internet skills."

Although in size and overall Internet capabilities Taipei is no Seoul, in terms of wireless penetration Taipei comes in at number one.

3. Tokyo, Japan


Internet in Japan is fairly cheap considering the speed trade off. Japan's most popular Internet option comes in the form of 100Mbps VDSL from Nippon Telegraph and Telephone (NTT) for $50 per month. For the truly ambitious Internet user, a 1Gbps fiber to the home (FTTH) option is available from Kansai Electric Power for $90 per month.

Because of the great speeds and availability Tokyo broadband users are able to obtain, web conferencing and VoIP calls have become the norm. In fact, the VoIP market in Japan totals more than 10 million unique IP lines.

Between 2005 and 2010 NTT plans on spending more than $40 billion making it the single most expensive telecommunications project in the history of the country. The renovations include plans for providing ubiquitous broadband for the entire country's 45 million households.

When it comes to raw broadband speed for the most number of users, Tokyo leads the world.

4. Hong Kong, China

As the case with most of the other Asian IT markets, broadband in Hong Kong is very cheap considering the amount of bandwidth provided. Hong Kong Broadband Network (HKBN), the leading IT company in the area, provides a 10Mbps residential connection for merely $16 per month. A 100Mbps connection costs $34 per month, making Hong Kong one of the few cities in the world with the ability to provide such high speeds to residential areas at an affordable cost.

HKBN also offers a broadband TV service equipped with more than 70 channels (displayed in DVD quality) on topics from the news to education to adult movies. Hong Kong is also in the process of pushing VoIP telephony technology as opposed to the old fashion telephone. HKBN offers a second generation broadband phone capable of video conferencing, instant messaging and all of the standard expected features for $6 a month.

If you're looking for the total digital experience, Hong Kong is your destination of choice.

5. Singapore

Compared to the other Asian epicenters, Singapore's Internet is relatively expensive as a 30Mbps connection costs around $77 per month. However, for the same Internet service in the United States, you would expect to pay at least $180 per month. Fortunately, if you're willing to have a few restrictions placed on your surfing, you can receive free 4Mpbs broadband from Singapore ISP StarHub.

When it comes to IT expansion, Singapore might be the most active country in the world. Last year, the Singapore government launched a 10 year plan to modernize the country's IT approach.

The plan calls for 80,000 new jobs, improving broadband penetration to 90 percent, improving IT assets and revenue and increasing broadband infrastructure capabilities to support IPv6 and speeds up to 1Gbps.

6. Stockholm, Sweden
TeliaSonera, the leading telecommunications company in Sweden, offers a 24Mpbs broadband Internet service for $50 per month pending the user signs an 18 month contract and uses a TeliaSonera phone which costs around $20 per month. Considering how expensive everything else in Sweden is, $70 per month for fast and reliable broadband is a steal.

While most cities are developing plans to increase the number of WiFi hotspots they have, Stockholm is busy engaging in a different type of wireless Internet technology:WiMAX. WiMAX is similar to WiFi in that it provides wireless Internet within a limited range. However, when it comes to the radius of the range and available bandwidth produced by the signal, WiMAX is far superior to WiFi (we're talking 20 feet versus 2 miles). Stockholm is currently testing ways to blanket the city in a WiMAX grid.

7. Various Municipal Projects, United States

With the invention of wireless mesh networks, WiFi access around the globe is beginning to increase at an exponential rate. Wireless mesh networks work by transmitting signals from strategically placed receivers (or nodes) within a network rather than one central location. In turn, the wireless signal is able to travel very large distances offering service to a record number of users.

Currently, several cities in the United States are taking on municipal WiFi projects to offer city wide Internet access at a very affordable (and occasionally free) price. Most of the cities' solutions involve some form of a wireless mesh network. Here are some of the cities experimenting with this technology.

8. Paris, France

Currently Paris is developing a strategy to employ city wide FTTH on an "open network." The project is currently being run by "Free", a subsidiary of French telecommunications company Iliad and is expected to take 5 years to complete costing around $1.3 billion. Subscribers to the service will receive a 50Mbps broadband connection, unlimited local calls (including some international options) and HDTV for $40 per month.

Not to be outdone, France Télécom is currently implementing an optical network capable of producing 2.5Gbps downstream speeds for its subscribers. The project is in developmental phases right now and available to a very limited number of users for $90 per month.


The government is also flirting with the idea of blanketing Paris in a WiMAX grid.

9. Shoreditch, England


For the most part, the United Kingdom has reasonable broadband options with an 8Mbps connection averaging between $40 and $80 per month. The U.K. is loaded with Internet hotspots and offers a wide variety of WiFi options. If you're looking to shop around and get the most bang for your buck, the U.K. boasts enough broadband plans (and prices) to accommodate the most infrequent Internet user to the biggest businesses. As for the nation's most connected city, however, one need look no farther than Shoreditch, a town in east London.

An experiment in Shoreditch to reduce the crime rate and improve the quality of living turns a user's television into a full scale digital device. The project is called "Digital Bridge" and includes broadband Internet on your TV, unlimited evening and weekend phone calls, digital TV and our favorite feature: Shoreditch TV.

10. Silicon Valley, United States

With companies residing in the area including Google, Cisco, HP, Intel and Yahoo!, you can be sure that Silicon Valley is sure to rank among the world's most connected regions.

It what proves to be the biggest wireless project yet, Silicon Valley (an area covering 42 municipalities and 1,500 square miles in California) plans to provide its 4.2 million residents with free WiFi. The project aims to offer 1Mbps wireless Internet free of charge and is being spearheaded by IBM and Cisco.

Currently several cities in Silicon Valley -- including San Jose, Mountain View, and Santa Clara -- already offer city wide WiFi to their residents, making the area a frequent candidate among world leaders in broadband penetration.

When it comes to Internet access and speed, these 10 cities are going above and beyond the status quo in providing the best technology at the right price to its residents. From DSL to Cable to Fiber in the home, these cities have combined both public and private efforts to ensure widespread accessibility at speeds much higher and rates much lower than their peers.



2. Read the abstracts of the full papers, and then make your comments.
Robin Kay, Developing a comprehensive metric for assessing discussion board
effectiveness, British Journal of Educational Technology, Vol 37 No5 2006. pp. 761-783
Comment:
論壇的快速發展與廣泛的應用,在近年快速成長,在我的感覺,他的功能似乎比Blog少了那麼一些,但是論壇的安全性與隱私性卻比Blog來的強。
將論壇應用在教學上,卻獲得比在課堂上更多的效益與幫助,使學生間的互動增加了,而在互動的過程之種,不止學生們能因討論而獲得更多的知識,連師長也能從中獲取不少的新觀念及想法。
研究顯示學生對於社會活動(social activity)很有興趣,社會”活動”不保證社會”學習”會發生;對認知處理(cognitive processing)的分析有證據顯示出學生有意願跟合作的常識了解新觀念;論壇參與跟課堂實際表現的關連指出在某種程度上有明顯的學習。

2007年12月21日 星期五

Homework 12-15-2007

1. Read the abstracts of the full papers, and then make your comments.
Feng Fua, Lianghuan Liua, and Long Wang. Empirical analysis of online social networks in the age of Web 2.0, Physica A: Statistical Mechanics and its Applications Volume 387, Issues 2-3, 15 January 2008, Pages 675-684

Comment:
此篇算是研究分析報告,目的在以統計及經驗法則,去分析Web2.0時代兩種有點相同又有點不同的東東,分別是Blog與SNS(社交服務網絡)。
在本篇論文中,他專注於兩個華人線上社交網路(online social network),sina blogs 和 Xiaonei SNS。第一個是最大的華人部落格提供者,在中國有超過兩百萬註冊者。後者是中國最大且最受歡迎的SNS。只開給大學生。在這論文有詳細的統計性質的經驗法則分析。發現這兩種網路都有小世界和無空間限制等特點,在實際世界觀察的到。而且degree(in/out) and degree(in/out) 和 clustering coefficient and degree 和 受歡迎度(觀看次數) and in-degree(部落格)之間的關係都研究過。並且顯示了部落格是屬於沒有分類的混合格式,但Xiaonei是有的。

2007年12月15日 星期六

Homework 12-1-2007

1. 查詢近期WiMax 產業分析報告ㄧ篇,作成100字摘要。
Comment:
Titel:WiMAX晶片業者發展現況
摘要:在WiMAX市場的發展上,晶片不僅是WiMAX產品中佔有成本比重相當大的零組件,對於其特性的影響也十分深遠,屬於上游零組件的晶片對於WiMAX的發展扮演相當重要的地位,WiMAX未來普及的狀況、終端產品的售價都將與WiMAX晶片的發展息息相關,本篇報告對於以下做分析:
一、WiMAX晶片市場的規模
二、全球WiMAX晶片廠商的發展現況
2.1:Intel
2.2:picoChip
2.3:Fujitsu
2.4:SEQUANS
2.5:Wavesat
2.6:Runcom
2.7:Beceem
三、TRI觀點


2. 簡述 Qualcomm收購Airgo與RFMD藍牙團隊的策略佈局為哪三項?
Comment:
(1)佈局下一世代無線關鍵技術:
Airgo是目前MIMO技術的領導業者,且又是802.11n的重要參與者,因此不論是MIMO抑或是OFDM,其都擁有許多相關專利與技術經驗,因此購併Airgo除了可強化平台完整度,配合上先前所獲得的Flarion,Qualcomm將不僅進可佈局未來的3.9G、4G等技術,亦有抵禦甚或進入WiMAX的能力。

(2)鞏固既有領域 - 提供完整行動通訊解決方案:
目前已成功進入手機的數位相機、MP3、藍牙連結,以及未來可望陸續導入的GPS、WiFi、行動電視等功能。因此,能同時提供多種包括網路連結與音樂、視訊等多媒體處理能力的平台產品遂成為各晶片業者努力的方向。

(3)搶佔新市場 - 放眼行動寬頻市場,挑戰Intel獨霸地位:
隨著Intel將其處理器結合WiFi、HSDPA(與Nokia合作)、WiMAX的行動運算平台策略已在NB上取得了大成功。可預期的,Intel緊接著將相當有可能繼續使用此WiFi/WiMAX行動平台策略來進軍UMPC,並再一次挑戰屢戰屢敗的行動通訊市場。而在這樣的意圖與發展策略下,取得WiFi、Bluetooth的佈局便也顯得相當自然不過了。

Bonus Problem:
3. 依據 WiMAX晶片業者發展現況此研究報告,目前全球主要WiMAX 晶片業者有哪幾家?
Comment:
全球WiMAX晶片廠商除了Fujitsu、Intel之外,尚有Beceem、Wavesat、SEQUANS、Runcom、picoChip等。

Homework 12-8-2007

Read the abstracts of the full papers, and then comment on the two papers.

1.Yao-Jen Chang, Tseng-Yun Wang, Shi-Kai Tsai, Yu-Chia Chuang, "Action Science Approach to Experimenting Nonprofit Web 2.0 Services for Employment of Individuals with Mental Impairments" 2007 International Workshop on Social Media Analysis in conjunction with ACM/IEEE Web Intelligence 2007. (EI)
Comment:
Web2.0的時代,加強了人與人間的互動,之前,可能每個人都必須撰寫及開發自己的網頁網站,才能將知識或技術公開,但在Web2.0的時代,很多如同Blog、Youtube、Wratch....等等,都讓人能及時的發表意見,使得撰寫與FeedBack更加的迅速。
而Web2.0使用的便捷與低成本的開發方式,更能讓身心障礙者,也能有一展長才的平台與空間,更多人性化的開發方法產生,讓更多的有障礙的人,能夠分享與獲得更多的知識。

2.Yao-Jen Chang and Chiu-Hui Chen, "Methodology and Evaluation of Teaching Computer Programming Laboratory with Social Media," ED-Media 2007, Vancouver, Canada, June 25-29, 2007.
Comment:
此篇文章提到的重點,就如同我們在這門課程用到最多的Blog,老師利用Blog寫下包含心得、上課教材、Talk Outline、Homework...等。
學生亦藉由Blog來呈現作業或是課程內容的Comment 及 FeedBack,藉此直接且公開的方式,便能讓同學及教師間的互動增加,可立即知道他人的想法,達到互相討論學習的目的,也因為Blog的公開,在學生學習及寫作上,更能加強尊重他人智慧的概念,減少抄襲的機會,因為藉由多重瀏覽比對,便能一覽無遺。

2007年11月24日 星期六

11-17-2007 Homework

Read the abstracts and skim the full papers, and then comment on the three papers.
1.Comment:

2.Comment:

3.Comment:

2007年11月22日 星期四

11-10-2007 Homework

1. Why does Pure Aloha perform worse than Slotted Aloha?
ANS:

reference:
2. According to Textbook pp. 2-48~2-51, why does 1-persistent CSMA have lower throughput than non-persistent CSMA when generated traffic rate is higher than 1 (G>1)? Why does 1-persistent CSMA have shorter latency than non-persistent CSMA?
ANS:
1-Persistent CSMA:
先偵測通道是否有載波,若是沒有立刻送出frame。
若偵測到有其他機器在使用通道,則持續偵測下去,等候到通道閒置時立刻傳送frame。
送出frame 之後,等候接收端的ACK,若未收到ACK,表示有碰撞發生。
若發生碰撞,必須等候一段隨機的時間,再重新傳送。
Non-Persistent CSMA(0-persistent CSMA):
偵測到有其他機器在使用通道,則不再持續偵測,而是隨機等候一段時間後才重新開始偵測。
每個frame 傳送的平均延遲比1-persistent 要長ㄧ點。

reference:資料通訊與電腦網路

2007年11月9日 星期五

10-27-2007 Homework

1. Read and then comment on the following papers.
1.1Yao-Jen Chang, Shan-Yao Wu, Ting-Liang Shih, Intersection Location Service and Performance Comparison of Three Location Service Algorithms for Vehicular Ad Hoc Networks in City Environments
Comment:
在這篇文章中,我們學習到ILS的性能,這是一個專門為了城市環境河路口設計的定位服務處裡系統。當對應的定位系統無法使用時,一個架構在Chord Algorighm系統的錯誤回復裝置會恢復汽車的位置資訊。分析模擬器會使用規則系統(GLS、HLS)來比對建議的計劃路線與其他兩個由定位系統的建議路線的表現作比較。模擬器的結果證明了在不同的網革路線圖下ISL計畫增加了成功的機率。我們也發現ISL規則系統不只在車輛高速行進下依然正常運作,也展現了這個系統在相當的網格路線下,有更高的可變空間。

1.2Yao-Jen Chang, Tseng-Yun Wang, Shi-Kai Tsai, Yu-Chia Chuang, "Action Science Approach to Experimenting Nonprofit Web 2.0 Services for Employment of Individuals with Mental Impairments" 2007 International Workshop on Social Media Analysis in conjunction with ACM/IEEE Web Intelligence 2007. (EI)
Comment:
Web 2.0 讓使用者成為資訊的提供者, 及時的更新、及時的訊息。 Blog/ WIKI 都是代表性的產物,即使是沒有網路基礎概念的人,只要他會打字、會上網,都能在幾分鐘內建立一個自己的Blog發表自己的意見,使用者不用去了解基本的程式設計、資料庫等問題。
而更加方便的,例如是 Discuz! 6.0.0 等論壇系統,更可有多元的搜尋、排列,讓使用者在彈指之間,便能找到想要的答案,當然將這些運用在腦部損傷的患者身上,更能提高閱讀或是工作的成效,使他們能或更多的效率及成就感。

2. Why is CSMA/CA instead of CSMA/CD used for 802.11?
Comment:
CSMA/CA:載波檢測多路存取/碰撞避免 (Carrier Sense Multiple Access/Collision Avoidance, CSMA/CA )是802.11無線區域網標準中採用的媒體存取控制(Media Access Control, MAC)方式。和乙太網MAC層採用的CSMA/CD不同的原因是:無線的環境、不容易確實的偵測是否有碰撞發生,所以修改被動的碰撞偵測的方式為主動的避免碰撞。CSMA/CA主要使用兩種方法來避免碰撞:送出資料前,聆聽媒體狀態,等沒有人使用媒體,維持一段時間後,再等待一段隨機的時間後依然沒有人使用,才送出資料。由於每個裝置採用的隨機時間不同,所以可以減少碰撞的機會。 送出資料前,先送一段小小的請求傳送封包(RTS : Request to Send)給目標端,等待目標端回應 CTS: Clear to Send 封包後,才開始傳送。 利用RTS-CTS交握(handshake)程序,確保接下來傳送資料時,不會被碰撞。 同時由於RTS-CTS封包都很小,讓傳送的無效開銷變小。

CSMA/CD:載波監聽多路訪問/衝突檢測(Carrier Sense Multiple Access with Collision Detection或簡寫CSMA/CD)是半雙工的乙太網的工作方式,它應用於OSI參考模型的數據鏈路層。用載波偵聽多路訪問(CSMA)時,有時儘管已偵聽通道空閒,但由於通道傳播遲延的原因,前面已發送的數據尚未到達對方,因此發送的數據仍會發生衝突。CSMA/CD是對CSMA方式的進一步改進。它是在偵聽通道空閒後,在發送數據時同時進行衝突檢測(CD),如果在發送數據過程中檢測到衝突,就立即停止發送數據,並等待一些時間,再重複發送。

2007年9月29日 星期六

Homework 9/22/2007

1. Read and then comment on the following papers.Yao-Jen Chang, Shih-Kai Tsai, Tsen-Yung Wang Wayfinding Systems Based on Passive RFID for Individuals with Cognitive Impairments Yao-Jen Chang, Tseng-Yun Wang, Yu-Chia Chuang, Shih-Kai Tsai, “Ontology-based Personalized Wayfinding System Using Deviation Detecting for Individuals with Cognitive Impairments” to be presented in International Conference on Convergence Information Technology 2007, Gyeongju, Korea. November 21~23, 2007. (EI)
A1:此二篇paper主要在針對Wayfinding(路向導航系統),在RFID方面:可以置入在不同的物件和地標上,利用行動通訊傳遞資料,不受空間和時間的限制,不僅操作容易、入門門檻低,且成本便宜,在最短的時間告知系統可讓受信者做出最快的反應,如果再加上語音的部分,那對於視障者更是有很大的幫助。在Q-Code方面:雖然Q-Code是較新的國際式二維條碼,能辨識率也極高,但終究是個條碼類產品,在使用人員無法親自以Reader去做辨識時,便失去它的作用,很明顯的,這在視障者的導航之中最明顯!綜觀:在我的觀點裡,作為Wayfinding的系統方面,還是以能自動發射的RFID會較為實用,而儲位儲物的管理,或許Q-Code會是較為節省金錢支出的工具。


2. Read Sec. 1-3-6 of Textbook.What is the disadvantage of Mobile IP and what's the solution?
A2:


3. According to lecture notes on Page 2, what is social network? Why is the positioning a major factor in mobile social network service?
A3:

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