4G RESOURCE MANAGEMENT RESEARCH

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4G/B4G cellular networks should be very spectral and energy efficient. The network resources need to be shared dynamically shared to provide high data-rate services. To get deep understanding of what are the current research interests around the world, we have investigated broadly on the following topics:
1.        Multicell resource management to control cochannel interference (32 papers);
2.        Dynamic resource allocation with different QoS requirements (33 papers);
3.        Impact of imperfect CSI (114 papers);
4.        Inter-cell interference mitigation (33 papers);
5.        Green wireless networks and energy-efficient resource management (26 papers);
6.        Interference control strategies (24 papers);
7.        Transceiver design with ARQ (31 papers).
In the following, we first briefly summarize these seven topics and then list our proposed research topics.


Part I: Multicell Resource Management to Control Cochannel Interference
In this part, we mainly discuss co-channel interference mitigation techniques for MIMO cellular systems (3GPP LTE Systems). MIMO and OFDM techniques have dominated almost all wireless communication systems. However, when it comes to a multi-cell environment, heavy intercell interference between adjacent cells is induced and significantly reduces performance and, especially, for those users at the edges of cell. As the future wireless communication systems prefer universal frequency reuse to satisfy increasing demand for high data rate transmission, intercell interference mitigation is becoming a very important issue, which must be taken into consideration when designing 3GPP LTE systems [1-2].
LTE provides flexible dynamic inter-base station cooperation for interference suppression, including the use of uplink (UL) reactive overload indicators (OIs) and proactive high interference indicators (HIIs) that provide bit maps of interference conditions on a per resource blocks (RB) basis. Downlink (DL) intercell interference coordination (ICIC) is supported through the use of DL relative narrowband transmit power (RNTP) bit maps providing a coarse power indication on a per RB basis [3-5].
1.        Intercell Interference Mitigation
Intercell interference mitigation techniques can be classified into three types: intercell interference randomization [6], intercell interference cancellation [7], and intercell interference coordination [8].
Intercell interference randomization randomizes the interference, treat it as white noise, and then mitigate it through processing gain, such as in CDMA systems. Intercell interference cancellation techniques are proposed to cancel interference at receivers by using iterative detector, smart antenna techniques or interleaved division multiple access (IDMA) schemes. Intercell interference coordination (ICIC) is based on a well-designed coordination of resource among users in adjacent cells to reduce interference and improve user capacity and coverage at cell edge.
As Intercell interference randomization does not directly reduce the interference and intercell cancellation only deal with some dominating interference, then intercell interference coordination/avoidance is the best solution to reduce intercell interference.
2．Existing Cancellation Methods
2.1 Fractional Frequency Reuse (FFR) [9-11]
In this methods, the assignment of subbands is fixed to each cell. Transmission of users in the system is carefully coordinated by base stations or even higher network entities to effectively avoid interference. Now, there are some existing proposals, such as Ericsson's Proposal, Alcatel's Proposal, Siemen's Proposal and Softer Frequency Reuse Proposal.

Fig.I-1 FFR model

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The Reversed Cultural Shock

I remember reading the article talking about some people stay in country long enough and when they come back to their original country, they find themselves not used to or even not comfortable with the life and culture once they were born with. People called it “reversed cultural shock”. Apparently, the US and China have many things uncommon, from the political system to how people do business. It is impressive to realize the difference when I have experiences in both countries for a while.

This is my second summer to come back to China. Apart from enjoying the happiness to see the family and friends, I have to reconnect myself to the rules and norms here, living as a Chinese in China. However, I wasn’t happy the first day on the street. The street is as crowded as it is in New York City, but people seem much more impatient. Horns blare at pedestrians; people go across the main street when the traffic light is still red; the rule of yielding traffic never works well. I have to watch out myself not to be hit by any car. It is scary. I then realize I have been too spoiled with the gentle drivers back in Austin: they always stop to let me go through first. I believe the safety of life and on the road as well as traffic laws should be always respected by every individual no matter where they are.

I am not supposed to be surprised or uncomfortable when I come back to China. It has been like this for a long time and I have stayed here for more than 20 years. Isn’t it? It seems awkward for people to say excuse me or thank you here. Being warm-hearted could be thought with special purpose and people are reluctant to offer help to people who need. Is it the reason why many people who have long been abroad are reluctant to come back because of the reversed cultural shock from their original countries? I believe they still love their own countries, their families and friends.

The current technology advances enable us to communicate with each other anytime, anywhere. The information about any subject from the media is also overwhelming, whereas the way people think, or the “culture” will never evolve as fast as a skype call. The two most frequent questions I have been asked is whether I will stay in the US and what the life looks like there. I understand even I were able to tell every difference between Chinese cuisine and Mexican or Italian one, they still wouldn’t know what it tastes like in the US.

It is usually taken for granted that once students are able to survive the English speaking environment and have progress academically, everything will be fine sooner or later. However, it is never easy to be in a different country as a young adult. Surviving in class and experiencing another culture is two very different stories to me. I find out many Chinese students tend to congregate as exclusive groups without talking to other students of different nationalities, which not only makes them isolated, but also reduces their precious opportunities to experience a different culture. It is then not surprising to see they won’t speak good English even after they stay in the US for a couple of years. Experiencing different cultures is not just go traveling or have the taste of different cuisines, it is a more comprehensive and critical understanding of one culture trough what we see and hear, from daily conversation to sitting in classroom, from reading newspapers to watching TVs. It also promotes a more critical understanding of their own country, including political, economic and social aspects. To achieve that goal, there are two things need to be done. 1. One must have a stronger language skill in order to communicate fluently with other students. Lack of enough speaking English skill keeps Chinese students from conducing further conversation and interaction. Language is the tool to communicate and exchange thoughts. English use is more than just sitting in class and doing homework in English. It should be long-term learning process through speaking and reading, much from outside of the class. Currently, I found out many Chinese students have the illusion that they believe they have mastered English because they prove their academic excellence. For some subjects, it is not hard to get good grades without much English language use, but it does not mean the language learning process is over. 2. The acceptance of culture difference. It is more of a psychological barrier to many Chinese students that they feel uncomfortable to talk to people from other countries. Especially when local Chinese live as a group, it is regarded as rebellious for one individual student to seek life in English speaking circle without sticking to the Chinese one. It is not objective to judge which culture is superior, but different cultures should be treated with respect and tolerance. Meanwhile, one should be able to open their minds to get to know another culture other than their own especially if they stay in another country.


The two difference

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1.        INTERFERENCE CANCELLATION FOR CELLULAR SYSTEMS: A CONTEMPORARY OVERVIEW
2.        Heterogeneous Cellular Networks: From Theory to Practice
3.        Wi-Fi Enabled Sensors for Internet of Things: A Practical Approach
4.        An Overview of  Cooperative Communications
5.        CMOS Software-Defined Radio Transceivers: Analog Design in Digital Technology
6.        LTE-Advanced: An Operator Perspective
7.        Overview of 3GPP LTE-Advanced Carrier Aggregation for 4G Wireless Communications
8.        From LTE-Advanced to the Future
9.        LTE-Advanced Modem Design: Challenges and Perspectives
10.        Networks on Chips:A New SoC Paradigm
11.        Outstanding Research Problems in NoC Design: System, Microarchitecture, and Circuit Perspectives
12.        Frontiers of Wireless and Mobile Communications
13.        CELLULAR SYSTEM PHYSICAL LAYER THROUGHPUT:HOW FAR OFF ARE WE FROM THE SHANNON BOUND?
14.        The Research University of the Future

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    Experience at Huawei Technologies

During the summer in China, I did my internship at Huawei technologies at Nanjng Research Center. Huawei is now the second largest telecommunications manufacturer in the world. The company was founded by a retired military officer 20 years ago selling routers and now has grown into a world class enterprise. It has an annual sale of more than 30 billion US dollars and I will not be surprised it will surpass Ericsson and become world No.1 telecommunications equipment provider in the very near future.

After I ever stepped into the building, I have the rumors and stories proved true. Engineers at Huawei (China) usually work at night after the regular 8 hours with intense amount of work. They have much less free time than their American counterparts. It is common to see people work on the weekends as well. The average age in company is relatively young and many people choose to leave the company after a few years. It is certainly understandable the constantly intense amount of work will not be thought as the first choice for life-long career. Engineers in Huawei receive a higher income in China, most of who get thirty to forty thousand dollars a year. Compared with their American counterparts, it is certainly an advantage for the company because most of the products are sold overseas.

The human labor cost is one of the core competitiveness for Huawei. What is more impressive for the Huawei miracle to me is the employee’s incredible endurance and commitment. I remember the first day I came into the company, I was handed a magazine with the employee’s essays. I skimmed some of the articles. Most of the articles are about how to maximize one’s potential, explaining one doctrine: Individual sacrifice is appreciated and encouraged, which is also beneficial to the employee oneself; the more you produce for the company, the more reward you can get. It is hard to strike the balance between work and personal time when the family issue emerges. Huawei dominated the African market. Engineers are able to suffer the bad living conditions in Africa to provide technical support.

During a meeting between President Obama and CEOs from Hi-Tech companies like Google and Apple, Obama asked how to get those manufacturing jobs back to the US, then Apple CEO Steve Jobs told Obama those jobs will never be back. The globalization and advances of supply chain have made more and more American companies move their factories overseas. They realize the manufacturing work can be perfectly done in countries like China and Philippines and save a lot of money at the same time. Some companies also outsource their jobs overseas to reduce costs. The advances of communications technology make the faster transfer of data possible and it is very convenient for engineers to work with each other on the internet. China and India are getting reward for producing a new generation of engineers. While American companies still keep its edge on technology and innovation, other countries are catching up. The gap is lessening.

Huawei is one of the companies which benefits from made in China. However, it is also designed in China and the company has been spending great amount of money on research. President Obama has realized that the key to keeping the US competitive is through innovation and education. He called upon more spending on research and education to nurture the best scientists and engineers in the world.

ldai

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