M2M系統(tǒng)用蜂窩調(diào)制解調(diào)器

　　通過利用運營商已經(jīng)安裝的蜂窩基礎(chǔ)設(shè)施，設(shè)計人員可以使用這個網(wǎng)絡(luò)，而不是Wi-Fi或替代網(wǎng)絡(luò)接口，用于收集數(shù)據(jù)或提供遠(yuǎn)程管理。對于小到中等規(guī)模的數(shù)據(jù)包來說，蜂窩網(wǎng)絡(luò)可以減少大型分布式系統(tǒng)的硬件預(yù)算，因為沒有本地Wi-Fi熱點或中繼器需要連接到蜂窩網(wǎng)絡(luò)的每個設(shè)備。此外，蜂窩調(diào)制解調(diào)器具有更長的距離（信號可以進一步）比Wi-Fi或其他無線網(wǎng)絡(luò)接口。

　　有多個蜂窩選項取決于您需要的數(shù)據(jù)傳輸速率和運營商在該地區(qū)需要連接?，F(xiàn)在使用的各種標(biāo)準(zhǔn)，包括GSM、GPRS、CDMA、HSPA、EVDO、CDMA，邊緣，和LTE。在一些地區(qū)，2G蜂窩服務(wù)可以提供低數(shù)據(jù)速率連接到約40千位/秒，更快的連接，3G服務(wù)，如邊緣和CDMA2000和HSPA+可以提供數(shù)據(jù)速率高達3.1兆位/秒和21兆位/秒，分別，而數(shù)據(jù)傳輸率最高，4g（LTE）服務(wù)，EVDO / CDMA和HSPA +可以提供高達100兆位/秒的數(shù)據(jù)傳輸速率，取決于載波。此外，公司現(xiàn)在正在致力于什么是所謂的5G網(wǎng)絡(luò)，這將提供另一個數(shù)據(jù)傳輸速度增加了十倍，當(dāng)它成為現(xiàn)實，可能在2016 / 2017幀時間或以后。

　　Luckily， for machine-to-machine （M2M） communications most data transfers do not involve large quantities of data， but， instead use short bursts of a few hundred to a few thousand bytes. However， transmission speed is still important — short， high-speed bursts of data will often consume less power than a slower， continuous stream of data. The short bursts allow the baseband processors to spend more time in their power-down modes， thus greatly reducing power consumption.

　　At the heart of any cellular modem is the baseband processor， which， thanks to the high volume of cell phones produced over the last few years， has been integrated down to a single chip， thus simplifying the design of the modem. A typical modem module in the Skywire family from NimbeLink （Figure 1） is squeezed into an XBEE module format （29 x 33 x 6.5 mm） that was created by Digi International. Such modules are also in widespread use on development boards， such as the various ARM-based Arduino processor boards.