4G Broadband Research Articles

Efficient multimode protocol architecture for complementary radio interfaces in relay-based 4G networks

Wireless networks of the next generation will satisfy user demand for a ubiquitous mobile broadband access. Current research efforts are therefore targeting the efficient realization of a flexible radio interface and network architecture. The wide range of application scenarios seems to prohibit a “one radio interface fits all” solution. Instead, it requires a multitude of solutions tailored for specific communication environments. Ideally, these solutions are related radio interface modes that have a common technology basis. This article presents a protocol reference architecture that enables the efficient integration of multiple such modes in a complementary way. This architecture essentially benefits from the commonalities between these modes. Hence it facilitates the coexistence and cooperation of different modes in all devices of a future relay-based radio access network: user terminals, access points, and relay nodes. This article focuses on the realization of the multimode capability of user and control planes and the related management of the protocols of a flexible radio interface. A proof of concept and its evaluation are presented at the example of relay-based 4G broadband networks and IEEE 802.16 (WiMAX).

STBC MIMO-OFDM peak-to-average power ratio reduction by cross-antenna rotation and inversion

Multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) has become a promising candidate for high performance 4G broadband wireless communications. However, like OFDM, one main disadvantage of MIMO-OFDM is that the signals transmitted on different antennas might exhibit a prohibitively large peak-to-average power ratio (PAPR). We will show that the PAPR reduction for MIMO-OFDM needs a more efficient solution than applying existing schemes for OFDM systems separately on each antenna. Further, we suggest a scheme of cross-antenna rotation and inversion (CARI), which utilizes additional degrees of freedom by employing multiple antennas. Two suboptimal schemes, termed successive suboptimal CARI (SS-CARI) and random suboptimal (RS-CARI) show significant performance advantages and lower computational complexity compared to the concurrent selective mapping (SLM) scheme proposed in Y. -L. Lee et al. (2003).

TD-CDM-OFDM: Evolution of TD-SCDMA toward 4G

TD-SCDMA, which is the homemade 3G standard in China, has received considerable attention and is believed to play a critical role in the development of China's mobile communication. Meanwhile, advanced MIMO and OFDM techniques shed light on the feasibility of high-performance 4G broadband systems. We discuss an evolutionary path of TD-SCDMA toward 4G systems in this article, which combines the existing advanced traits in TD-SCDMA with new features for broadband wireless communication systems.

Setting a business strategy to weather the telecommunications industry downturn by using fuzzy MCDM

Telecommunications deregulation, the exponential increase in internet IP applications, and the emergence of 3G broadband mobile services have created tremendous growth in the telecommunications industry in the past few years. However, the recent abrupt economic slowdown has resulted in mass corporate restructuring and workforce realignment in the telecommunications industry. During this telecommunications downturn, how to promptly implement a business strategy to weather the economic storm has become a critical issue. Often, corporations do not know how to evaluate a company's qualitative issues while setting a business strategy. This, in turn, could cause long-term negative impact on a corporation. The purpose of this paper is to help corporations in evaluating fuzzy qualitative issues during business development by employing a fuzzy MCDM method. An empirical formula is employed as an example to examine the practicability and usefulness of this method. Study results show that the R&D focus has the highest ranking among all of the strategies examined.

A fourth-generation MIMO-OFDM broadband wireless system: design, performance, and field trial results

Increasing demand for high-performance 4G broadband wireless is enabled by the use of multiple antennas at both base station and subscriber ends. Multiple antenna technologies enable high capacities suited for Internet and multimedia services, and also dramatically increase range and reliability. In this article we describe a multiple-input multiple-output OFDM wireless communication system, lab test results, and field test results obtained in San Jose, California. These are the first MIMO system field tests to establish the performance of MIMO communication systems. Increased capacity, coverage, and reliability are clearly evident from the test results presented in this article.

Applying IP over wmATM technology to third generation wireless communications

With the rapid development of third-generation wireless mobile communication systems worldwide, the wireless mobile ATM enhanced software radio platform has taken the lead in the implementation process, which helps construct a broadband wireless pipe and "IP over wmATM" open signaling suite to support various common air interfaces for the wireless industry. This article presents the implementational issues using the IP over wmATM solution for 3G broadband wireless mobile communication systems. It includes the design of the wmATM medium access controller, protocol stack, wmATM module definition, and software radio platform, as well as IP unified 3G wireless networks.