g***u
发帖数: 4 | 1 Guanghui Liu, and Weile Zhu, "Phase Noise Effects and Mitigation in OFDM
Systems over Rayleigh Fading Channels," wireless personal communications,
DOI: 10.1007/s11277-006-9141-7
Published online: 1 September 2006
帮忙寄到: g*******[email protected]
不甚感激！ |
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p********d
发帖数: 3 | 2 rt,
been asked a couple of times, but no good answer.
Thanks!! |
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m**o
发帖数: 10 | 4 I am here.
How should I play? |
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k*********a
发帖数: 14 | 5 For multiuser, use MIMO-OFDMA as in Wimax. |
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a*******e
发帖数: 346 | 6 1。理解我认为没错
2。frequency-selective channel可以通过OFDM转化成很多窄带信道
所以很多MIMO只讨论窄带
varying
filter |
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k*********a
发帖数: 14 | 7 The remaining 12 tones are used for: pilots (4), DC tone, and guard tones.
The 52 tones are used for PSDU transmission. |
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r*****f
发帖数: 247 | 9 小弟做无线的,基本就是MIMO OFDM, cooperative communication之流的东西.
最近临毕业找工作,发现faculty教职基本没有这个方向要人,最热的集中在nano,vlsi,
circuit,RF等(也没看到network和information theory).所以崩管你牛不牛,人家压根
不要人.有些人建议到牛校做postdoc,再试试. 我就有点纳闷,首先,做postdoc肯定还是
这个方向,人家请你是去写paper的,总不能转行学东西吧. 即便搞了2年postdoc经验又
如何? 通信的职位只能一年比一年少. 虽然竞争力强了,但是坑少了,不划算啊.
industry倒还有一些职位,虽然不是完全对口,但是申请应聘应该还有希望.我觉得
industry里通信也做不了太久,通信不像计算机,换个花样就能出新游戏,新平台,新软件
,新引擎. 通信在标准确定后公司就不需要大量研发了,裁人可能是不可避免的后果. 这
样就面临转型,是后话,就不讨论了.
总之现在很迷茫, 大家觉得继续postdoc好,还是跳到公司好? 讨论讨论. |
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m**o
发帖数: 10 | 10 Please send me your resume if you are interested.
General Area: wireless communications and networks, physical layer algorithm
and design. MIMO/OFDM/Coding/Modulation/
I will try to find a detailed job description if possible.
Work Place: Bay area/San Jose, CA
Email: m*******[email protected] |
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r*****f
发帖数: 247 | 11 嗯。。我做的偏MIMO OFDM，所以sumsung跟qualcomm是首选。但是想进qualcomm太难。
所以samsung最终可能是首选了。 |
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d***s
发帖数: 55 | 12 新手弱问，只是搜到了英文
Scalable Orthogonal Frequency Division Multiple Access
Orthogonal Frequency Division Multiplexing
但是有啥区别和联系？ |
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w**********m
发帖数: 82 | 14 比如在OFDM系统中，接受信号和发送信号的关系是
y(m)=C(m)X(m)+w(m)
这里，m是time index，C(m)是要估计的channel impulse response vector。
w(m)是高斯白噪声。系统的多普勒频移是fd，可以很高。
通常在time domain中用RLS算法估计第n时刻的C(n)是
min sigma [y(m)-C(m)X(m)]^2 lambda^{n-m}
sigma中的m从0到n。lambda是forgetting factor，小于1.
如果引入smoothing算法的话，估计n时刻的C(n)是
min sigma [y(m)-C(m)X(m)]^2 lambda^{abs(n-m)}
m从0到整个Packet的结尾。
现在的simulation 结果是用了smoothing反而效果变差了。
确实比较想不通。那位能解释一下？
再说一下packet的结果。有4个pilot symbol，加上10个data symbol。
后面的data symbol的估计值是通过decision directed方式得到的。 |
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f******r
发帖数: 333 | 15 我在澳洲读的wireless communications的研究类硕士（这边分课程类和研究类，后者
就是要多灌水，我也灌了一些conference和journal的了），马上毕业了，现在想申美
国的PhD。
感觉现在wireless communications方向有点没落了，我想换成对进入工业界找工作有
帮助的方向。
我没有学过电路设计之类的课程，主要学的就是信号处理，无线通信方向的课程，现在
做的东西也是MIMO+OFDM的被做滥的东西。。。
想请教一下大家像我这样情况的申请哪个方向好一些呢？
谢谢了~~~ |
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f******r
发帖数: 333 | 16 十分感谢前辈回复啊~
现在好像全球的通信工作都不景气，澳洲这种没有研发的地方工作机会更是少得可怜~~
因为我硕士阶段读的是无线通信这样的火炕方向，而且我是研究类的，没上过课，只是
天天读paper,灌水，水倒是灌了一些，可是导致我现在在澳洲找工作很头疼，去美国找
的话好像更没有什么希望，但是又不想马上回国，所以比较尴尬~
所以在我看起来，读PhD就成了一种必要选择~
这位前辈说“PhD from Australia is fine.”不过我身边确实没有学通信的去美国的
例子。仅有的几个相关例子，我们组有搞天线的PhD(一个波兰裔的小伙，长在澳大利亚
)，去了Apple，好像还是搞iphone;还有一个澳洲人搞芯片的，据说先去了加州的一个
小公司……
但是这样的例子放在我身上好像都不可复制。
我自己现在倒是拿到了墨尔本大学的offer, （学校排名放在澳洲这里还算凑合了，可是我心里清楚一放到美国就什么都不是了），可是方向还是无线通信（看那老板好像还
是在玩MIMO-OFDM），所以我自己是十分的犹豫，到底去还是不去呢~~
所以特别想听听你们在美国留学的人看看还有什么方向值得学的~ 感觉P |
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z*****n
发帖数: 7639 | 17 In 802.11b one channel is defined as 5Mhz bandwidth, and
working at 2400-2483Mhz ISM band.
But due to the modulation sideband, a 20Mhz seperation is
necessary. So at most 3 channels can be used at the
same place.
802.11g uses OFDM, and one channel is 20MHz, just
back-compatible with 11b. |
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z*****n
发帖数: 7639 | 18 see my previous post, there are 52 "subcarriers" in
one "channel" of 802.11g.
802.11a/g use OFDM, I think you didn't get this point. |
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r****g
发帖数: 2 | 19 就目前来说，最成熟的短距通讯标准，还是BLUETOOTH。虽然不是官方标准。但有一整
套的PROFILE。 UWB一是硬件难突破，另外没有统一的标准。所以基本已经没有大的公
司支持的。zigbee是IEEE的SENSOR NET，所以做RF前端的时候可以用现成的标准。
Wimax是基于OFDM和MIMO无线局域网。 不是短距。 耗电也没法做成PORTABLE。 |
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w******t
发帖数: 241 | 20 两者底层好像都是OFDM+MIMO吧，那主要区别是在网络层上？如果只是在网络层面的差
别，那么同时部署两个应该问题不大啊？哪位达人解释一下 |
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w******t
发帖数: 241 | 21 两者底层都是MIMO+OFDM实现吧，技术细节上差别主要在哪里？ |
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r*****d
发帖数: 44 | 22 For UL, LTE uses Single-carrier OFDM, not
WCDMA-based. |
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b***n
发帖数: 13455 | 23 For uplink, LTE uses SC-FDMA to boost PA effciency, while WiMAX sticks with
OFDM, which has high peak-to-average power ratio.
For downlink, both uses PFDMA. But LTE organizes the available spectrum into
smaller chunks, while WiMAX optimizes for maximum channel usage by
processing all the information in a wide channel.
WiMAX radio is much simpler as it implements using TDD, while LTE goes with
FDD for true full-duplex operation. |
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m*******e
发帖数: 6 | 24 主要研究PAPR,ISI,ICI问题,我是数学出身
明年去美国访问一年,每月只有1200美圆
希望大家提供一些信息 |
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f*****l
发帖数: 82 | 25 I can only say u did not mention you goal...
No information, how to recommend... |
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c*****n
发帖数: 1877 | 26 Li不错，Ma好像是水车的徒弟?她本人是不是水车就不知道了。 |
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f*****l
发帖数: 82 | 29 How can you call GG 水车?
I don't think the quality of GG's journal papers are bad....
According to your argument, Li is the postdoc of another 水车......
It is very impolite to call those bull professors 水车.......
Btw, Li is good in terms of his publications. |
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c*****n
发帖数: 1877 | 30 I once read several journal papers of GG. They are quite similar. In my
opinion, he should be called water-car, eventhough he has also published
many good papers and become an IEEE fellow.
By the way, his water-car nickname is not origined from me, somebody here
said so before. |
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W*****e
发帖数: 7759 | 31 GG definitely deserves this nickname. BTW you can't imagine his reaction
once his paper got rejected. I think that's way too much... |
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a*******e
发帖数: 346 | 32 访问学者来美国就是轻松一下。 好好玩一年，呵呵 |
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m****y
发帖数: 74 | 33 i recall that hassibi and tarokh groups have done some earlier work on par
reduction. it makes more sense for you to try these places since these names
definitely will be more useful, and also since they are more math-oriented.
.. |
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c**l
发帖数: 159 | 34 Since you only have one year, most likely you only have time to get a chance
to know what they are working on and how they approach problems. You
probably will realize that there are very few super cows. In some aspects,
you are probably better than your adviser. And he or she depends on you to
make new contributions.
Which two are you interested in? |
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n*******d
发帖数: 124 | 36 GG is absolutly water-car.
I once helped to review one of his journal paper submission and rejected it.
He is already tenured and I don't understand why he does not try to publish
some high-quality papers only.
I also know some of his PhD student. |
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h**0
发帖数: 37 | 37 read wimax specification |
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a******n
发帖数: 23 | 38 Google一下就好了。
WiMAX的基带没什么太fancy的东西。 无非是OFDM+MIMO |
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g*****e
发帖数: 87 | 39 Most of the LTE R&D work are done in Europe. There are very very few
candidates for HW to choose in North America.
As I know, there are only few people from VZW and AT&T CTO group have some
exposure to LTE.
Most of the experiences people have from 2G and 3G don't really help as the
system is re-engineered completely: the air interface is all OFDM based and
core network is all IP based. The fresh graduates are perfect for these
kinds of positions.
No company can hire the people with the skill set |
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m****y
发帖数: 74 | 40 if u meant ofdm based "uwb", then probably yes; remember there are still
impluse based uwb. after all, i do agree that it will be a niche market only
. |
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i****5
发帖数: 11 | 41 你们说的wireless都是指做纯物理层的？mimo ofdm之类的？
还是范围更大？ |
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g*****e
发帖数: 87 | 43 GSM and GPRS jobs are pretty much done in US. Don't waste your time on them.
There are lots of commercial 3G planning, simulation and optimization tools
in the market, it is already saturated now.
Try to learn some OFDM stuff and prepare to work on LTE stuff. VZW is filed
trying it in field now. at&t probably starts it next quarter. |
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k***d
发帖数: 536 | 44 I don't know why you fail, but i think you need to know much more about OFDM
, that is on which QCOM's future depends, it is one of the core patent
claims QCOM has, you need to be familiar with it. |
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p******n
发帖数: 156 | 45 My main research is on MIMO and CDMA. There is just one sentence about OFDM
in my resume.
But he didn't ask anything about MIMO or CDMA. |
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s********k
发帖数: 6180 | 46 关键问题是面试你的人肯定不是从你的简历出发问，而是他们的需求出发。CDMA显然
QCOM已经不敢兴趣了。不过没有问你MIMO有点奇怪。
OFDM |
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g****t
发帖数: 31659 | 47 你没把自己的research写到resume? 他没问你研究生期间干了啥？
wierd wierd...
OFDM |
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p******n
发帖数: 156 | 48 写了,我整个rusume几乎都是关于mimo的,ofdm就一句话 |
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p****n
发帖数: 69 | 49 I think intra-cell interference would be a much bigger problem for femto
cell than inter-cell interference. The reason is usually adjacent cells use
different frequency. But for users in the same cell, they may use the same
range of frequency. Usually if both users connect to the same base station,
a central controller can manage the intra-cell interference by assigning
different OFDM sub-band or using orthogonal codes in a CDMA fashion, etc.
Now femto and base station probably would act indepen |
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Y**********l
发帖数: 104 | 50 谢谢！
好像OFDM， MIMO等技术还没有用到RFID中？ |
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