目前，有十幾家企業(yè)，都已表態(tài)支持一項(xiàng)才剛剛提議的長(zhǎng)期演進(jìn)(LTE)標(biāo)準(zhǔn)，該標(biāo)準(zhǔn)將可實(shí)現(xiàn)裝置到裝置之間的鏈接。這些公司相信， Direct LTE 將為不適合使用 Wi-Fi Direct 和 GPS 的適地性應(yīng)用，提供更具能源效益的服務(wù)。 Direct-LTE 是以500公尺的可視范圍鏈接和20-23 dBm的訊號(hào)限制為基礎(chǔ)，該技術(shù)能更快地找到本地使用者，而且所需的處理開銷要比Wi-Fi Direct 或 GPS 要少得多，高通(Qualcomm)技術(shù)銷售總監(jiān) Mahesh Makhijani 在 NGMN Alliance 大會(huì)上表示。 高通透露，在該公司的內(nèi)部測(cè)試中， LTE Direct 能在0.64秒內(nèi)發(fā)現(xiàn)多達(dá)7,200個(gè)終端，相較之下， Wi-Fi Direct 則需要82~119秒才能發(fā)現(xiàn)369個(gè)終端。另外，高通的測(cè)試還發(fā)現(xiàn)，造成 Wi-Fi Direct 可發(fā)現(xiàn)終端數(shù)量大幅減少的延遲，將會(huì)隨著終端設(shè)備密度的提升而變嚴(yán)重。 然而，Makhijani表示， LTE Direct 可以和 Wi-Fi Direct 并存。例如，在某些情況下，當(dāng)終端裝置已經(jīng)使用 LTE Direct 連接后，還是可以經(jīng)由 Wi-Fi Direct 來傳送資料，他說。 包括阿爾卡特朗訊、德意志電信、LG電子、NEC和諾基亞等電信業(yè)者、系統(tǒng)廠和芯片公司都支持這個(gè)想法。他們提出了將 Direct LTE 增添到 3GPP 組織的 LTE Release 12標(biāo)準(zhǔn)中的構(gòu)想，該標(biāo)準(zhǔn)預(yù)計(jì)2015年問世。然而，為了讓 Direct LTE 更容易導(dǎo)入產(chǎn)品設(shè)計(jì)，3GPP組織可能會(huì)考慮定義一個(gè)ad hoc標(biāo)準(zhǔn)。 Direct LTE可以支持“就近服務(wù)，進(jìn)而為移動(dòng)網(wǎng)絡(luò)提供更多價(jià)值，”Makhijani說。 少數(shù)的新興移動(dòng)應(yīng)用都采用了 FourSquare Radar 和Twitter Discovery tab 等更具環(huán)境感知能力的技術(shù)。過去一年來，投顧業(yè)者已針對(duì)上述二家業(yè)者投資了約五億美元，Makhijani表示。 高通也在大會(huì)中展示了Direct LTE的仿真成果。在手機(jī)應(yīng)用中，該技術(shù)需要升級(jí)的收發(fā)器，而這些收發(fā)器都尚未應(yīng)用在目前的芯片組中。 編譯： Joy Teng 本文授權(quán)編譯自EE Times，版權(quán)所有，謝絕轉(zhuǎn)載 本文下一頁(yè)：參考英文原文：Look Ma, no network: Group drives LTE Direct ，by Rick Merritt

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{pagination} Look Ma, no network: Group drives LTE Direct Rick Merritt SAN FRANCISCO – More than a dozen companies are supporting a proposed standard for device-to-device links in Long Term Evolution handsets. They believe Direct LTE will offer capabilities and power efficiency for location-based applications not available with today’s Wi-Fi Direct and GPS links. Direct-LTE is based on line-of-sight links at a range up to 500 meters and 20-23 dBm signaling limits. The technique could discover local users more quickly with less processing overhead than Wi-Fi Direct or GPS, said Mahesh Makhijani, a director of technical marketing at Qualcomm, in a presentation at the conference here of the NGMN Alliance. Qualcomm said in its internal tests, LTE Direct discovered as many as 7,200 terminals in 0.64 seconds compared to 369 terminals found in using Wi-Fi Direct that took 82 to 119 seconds. The chip makers tests also found latency for Wi-Fi Direct discovery degraded significantly as device density increased. Nevertheless, Makhijani said LTE Direct could work with Wi-Fi Direct. For example, in some cases it might be more useful to send data via Wi-Fi Direct after devices had been found using LTE Direct, he said. A wide range of operators, system and chip companies back the idea, including Alcatel-Lucent, Deutche Telekom, LG, NEC and Nokia. They proposed adding Direct LTE to the 3GPP group’s LTE Release 12, slated to be available in 2015. However, the group may consider defining an ad hoc standard to get Direct LTE into products earlier. Direct LTE could support “proximity services that provide more value to the mobile network,” said Makhijani. A handful of emerging mobile applications are adopting the concept of ambient awareness including FourSquare Radar and the Twitter Discovery tab. Venture capitalists spent an estimates $500 million on the theme over the last year, said Makhijani. Qualcomm showed a simulation of Direct LTE at the event. The technique requires upgraded transceivers in handsets, not yet available in current chip sets.