Chapter 0: Overview Wireless Network Architecture & Potential Research Directions Yu-Chee Tseng Dept of Computer Science National Chiao-Tung University Ch0:1
國 立 交 通 大 國 學 立 資 交 訊 通 工 大 程 學 系 資 曾 訊 煜 工 棋 程 系 教 授 曾 煜 棋 教 授 Ch0:2
Wireless Network Models With Infrastructure: Without Infrastructure (ad hoc networks): Ch0:3
Cellular: Infrared: Ch0:4
As relaying link Packet Radio Network Ch0:5
無 線 隨 意 網 路 (Multi-hop Ad Hoc Network) Laptop Laptop A Laptop Laptop C' B D PDA E Laptop LaptopC Laptop PDA PDA PDA Ch0:6
感 測 網 路 (Sensor Network) Ch0:7
Nokia Rooftop Product Ch0:8
The Ricochet Network Overview Modem Internet and Corporate Networks 900 MHz Poletop Radio 2.3 GHz 2.4 GHz Wired Access Point High-speed dedicated wired connections Network Interface Facility Ch0:9
Easy Installation Ch0:10
Bluetooth Technology bluetooth headset bluetooth dongle bluetooth MP3 watch Ch0:11 bluetooth remote car control
Research Directions: Mobile Computing, Communications, and MEMS Technologies Ch0:12
Three Directions Together Wireless Communication Technology Portable Computer Technology appearance of light-weight computing devices MEMS Technology 微 機 電 系 統 (Micro Electro Mechanical Systems,MEMS), 其 定 義 為 一 個 智 慧 型 微 小 化 的 系 統, 包 含 感 測 處 理 或 致 動 的 功 能, 包 含 兩 個 或 多 個 電 子 機 械 光 學 化 學 生 物 磁 學 或 其 他 性 質 整 合 到 一 個 單 一 或 多 晶 片 上 其 應 用 領 域 極 為 廣 泛, 包 括 製 造 業 自 動 化 資 訊 與 通 訊 航 太 工 業 交 通 運 輸 土 木 營 建 環 境 保 護 農 林 漁 牧 等 Vision: Ubiquitous/ Nomadic Computing, communication, and control computers everywhere; information anywhere anytime control 國 立 交 通 大 學 資 訊 工 程 系 曾 煜 棋 曾 煜 棋 教 授 Ch0:13
Features of Wireless Communication one global bandwidth shared by all users fortunately channels, such as (frequency, time-slot) pairs, can be reused Radio-based low bandwidth high latency radio communication links higher bit error rate (BER) fading short-term multipath fading (Rayleigh effect) due to same signal taking different paths and arriving at the receiver shifted in phase long-term fading (radio shadow) 國 立 交 通 大 學 資 訊 工 程 系 曾 煜 棋 topology of the terrain (like mountains) can cause signal dropouts 曾 煜 棋 教 授 Ch0:14
Features of Portable Computers Limited resources: limited energy (battery life) limited CPU speed limited memory limited display Mobile Applications/Services Pico-service: local parking lot availability, layout of a building Micro-service: train and bus station information Macro-service: weather information, news service, stock market information Real-time multimedia applications tele-medicine collaborative working environment 國 立 交 通 大 學 資 訊 工 程 系 曾 煜 棋 曾 煜 棋 教 授 Ch0:15
Features of MEMS MEMS (Micro Electro Mechanical Systems) are the integration of electrical devices and mechanical structures at the micrometer (10-6 m = 0.000001 m) scale. The essence of MEMS is their ability to perform and enhance tasks, in ways and in the micro world, impossible using conventional technologies. digital propulsion Microthruster optical switch segway Ch0:16
Research: Hardware Aspects power saving display, LCD low-voltage CPUs Example: AT&T's Hobbit chip: 5,000 times less power consumption in doze mode than active mode radio: an example of IEEE 802.11 power consumption transmit: 1400 mw receive: 1000 mw idle: 830 mw sleep: 130 mw transmitting 1 bit is equal to executing > 1000 instructions Ch0:17
Research: Software Aspects mobile communication protocols WAP wireless TCP Mobile IP MAC protocols Energy-efficient protocol related to the above send/receive/idle/sleep model Mobile Operating Systems: Windows Mobile, Android, etc. Ch0:18
Research: Application Aspects Compute, communicate, and micro-control Context-aware computing context includes user's location environment (e.g., noise level, communication b/w, communication cost etc.) social situation (e.g., with boss, with co-worker etc.) context-aware applications context-sensitive information access (e.g. where are the bookstores in the vicinity) context-sensitive commands: in active badge system command format: <badge> <location> <event-type> <action> Ex: Coffee Kitchen arriving play -v 50 ~/sound/rooster.au 國 立 交 通 大 學 資 訊 工 程 系 曾 煜 棋 曾 煜 棋 教 授 Ch0:19