Mathematical Handbook for Scientists and Engineers

This chapter contains sections titled: Introduction Overview of Multicarrier CDMA Systems Channel Model Performance of MC-CDMA System Performance of Overlapping Multicarrier DS-CDMA Systems Performance of Multicarrier DS-CDMA-I Systems Performance of AMC DS-CDMA Systems Performance of SFH/MC DS-CDMA Systems Chapter Summary and Conclusion 
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Overview of Multicarrier CDMA

Aspects of the subject disclosure may include, for example, receiving, by a feed point of a dielectric antenna, electromagnetic waves from a dielectric core coupled to the feed point without an electrical return path, where at least a portion of the dielectric antenna comprises a conductive surface, directing, by the feed point, the electromagnetic waves to a proximal portion of the dielectric antenna, and radiating, via an aperture of the dielectric antenna, a wireless signal responsive to the electromagnetic waves being received at the aperture. Other embodiments are disclosed.

Method and apparatus for coupling an antenna to a device

A distributed antenna and backhaul system provide network connectivity for a small cell deployment. Rather than building new structures, and installing additional fiber and cable, embodiments described herein disclose using high-bandwidth, millimeter-wave communications and existing power line infrastructure. Above ground backhaul connections via power lines and line-of-sight millimeter-wave band signals as well as underground backhaul connections via buried electrical conduits can provide connectivity to the distributed base stations. An overhead millimeter-wave system can also be used to provide backhaul connectivity. Modules can be placed onto existing infrastructure, such as streetlights and utility poles, and the modules can contain base stations and antennas to transmit the millimeter-waves to and from other modules.

Backhaul link for distributed antenna system

A distributed antenna system is provided that frequency shifts the output of one or more microcells to a 60 GHz or higher frequency range for transmission to a set of distributed antennas. The cellular band outputs of these microcell base station devices are used to modulate a 60 GHz (or higher) carrier wave, yielding a group of subcarriers on the 60 GHz carrier wave. This group will then be transmitted in the air via analog microwave RF unit, after which it can be repeated or radiated to the surrounding area. The repeaters amplify the signal and resend it on the air again toward the next repeater. In places where a microcell is required, the 60 GHz signal is shifted in frequency back to its original frequency (e.g., the 1.9 GHz cellular band) and radiated locally to nearby mobile devices.

Remote distributed antenna system

In this paper, we propose a dynamic channel assignment (DCA) scheme for distributed antenna networks (DANs). DANs, in which many antennas are distributed in each cell, significantly reduce the transmit power compared to conventional cellular networks (CNs). In DAN, a different group of channels should be assigned for each distributed antenna to avoid the interference. Since DAN can also reduce the interference power due to its low transmit power property, the same channel groups can be reused even within the same cell. Proposed DCA scheme dynamically assigns the channels based on the co-channel interference measurement. Computer simulation results demonstrate that the DAN using proposed DCA achieves higher spectrum efficiency than the conventional CN.

http://www.mobile.ecei.tohoku.ac.jp/paper/pdf/inter_2012/07_in_2012_matsukawa.pdf

A Dynamic Channel Assignment Scheme for Distributed Antenna Networks

In a frequency reusing wireless local area network (WLAN), the co-channel interference (CCI) environment will change when new access points (APs) join the network. Therefore, the user throughput reduces if the available channels are not properly re-allocated. A newly joined AP is designed to measure the CCI levels on the available channels to select the best channel which experiences the lowest CCI (this is referred to as the conventional channel assignment). However, old APs' channels are not anymore the best since the CCI environment has changed after the new one joined. If each AP periodically measures the CCI environment and reselects the channel experiencing the lowest CCI, the throughput may improve. This is called the dynamic channel assignment (DCA). In this paper, we apply the channel segregation based DCA (CS-DCA) to WLAN. In order to examine the channel distribution pattern obtained by CS-DCA, we introduce three indicators: the autocorrelation of channel distribution pattern indicating the degree of stability, the deviation of channel reusing, and the minimum co-channel AP distance. We confirm by computer simulation that the CS-DCA can autonomously form a channel distribution pattern which minimizes the CCI at each AP and that the CS-DCA improves the signal-to-interference-ratio (SIR) compared to the conventional scheme.

Channel segregation based dynamic channel assignment for WLAN

In the future wireless communication systems, the broadband wireless technology which enables Giga-bps class data services is demanded. Broadband wireless channels become extremely frequency-selective and cause severe inter-symbol interference (ISI). Furthermore, the average received signal power changes in a random manner because of the shadowing and path losses according to the movement of a mobile terminal (MT). Accordingly, the transmission performance severely degrades. Development of some advanced equalization and networking is necessary to overcome the performance degradation. Among them, promising are the frequency-domain equalization (FDE) and distributed antenna network (DAN). The former takes advantage of channel frequency-selectivity to obtain the frequency-diversity gain. In DAN, a group of distributed antennas serve each user to mitigate the negative impact of shadowing and path losses. This article will introduce the recent advances in FDE and DAN for the broadband single-carrier (SC) transmissions.

https://www.mobile.ecei.tohoku.ac.jp/paper/pdf/inter_2009/32_in_2009_adachi.pdf

Recent advances in single-carrier frequency-domain equalization and distributed antenna network

For gigabit wireless data services, there are three important technical issues to be addressed: limited bandwidth, severe frequency-selective fading, and limited transmit power. A distributed antenna network (DAN) is a promising solution to the above three technical issues. In this paper, recent advance in gigabit DAN is presented. In DAN, each mobile user is served by using multiple distributed antennas close to it. Particular attention is paid to frequency-domain multi-input/multi-output (MIMO) diversity, relay, beamforming, and multiplexing jointly used with frequency-domain equalization (FDE) to significantly improve the signal transmission quality over a service area.

http://www.mobile.ecei.tohoku.ac.jp/paper/pdf/inter_2011/08_in_2011_adachi.pdf

Distributed antenna network for gigabit wireless access

In this paper, space-time block coding (STBC) is applied to single-carrier distributed antenna network (SC-DAN). By using the frequency-domain STBC coded joint transmit/receive diversity (FDSTBC-JTRD) for the downlink while using the well-known frequencydomain space-time transmit diversity (FD-STTD) for the uplink, the diversity order is given by the product of the number of distributed antennas and that of mobile terminal (MT) antennas. It is shown by computer simulation that the downlink and uplink can achieve almost the same bit error rate (BER) performance and that by increasing the number of distributed antennas, the BER performance can be significantly improved while keeping the MT complexity low.

Tatsunori Obara

Papers

A Dynamic Channel Assignment Scheme for Distributed Antenna Networks

Channel segregation based dynamic channel assignment for WLAN

Recent advances in single-carrier frequency-domain equalization and distributed antenna network

Distributed antenna network for gigabit wireless access

Frequency-domain space-time block coded single-carrier distributed antenna network