Joint channel &amp; polarization assignment for capacity enhancement in non line-of-sight fixed wireless networks

Sharif

2006

Wireless Pers Commun

The scarcity of available spectrum in the 2-11 GHz frequency range and the continuously increasing number of users that require broadband communication services suggest that emerging fixed-broadband wireless access (F-BWA) networks will be deployed with aggressive frequency re-use to cope with capacity demands. In this context, co-channel interference may arise in high levels compromising the system's capacity and robust operation. Interference is further increased when limited directionality terminal antennas are employed to support non line-of-sight operation and in the case where an adaptive-time division duplex is selected for efficient radio resource management in asymmetric and time-varying traffic conditions. In this paper frequency channel assignment (CA) and antenna polarization assignment (PA) are considered as a means of mitigating interference. Two novel CA schemes that consider the distinct characteristics of F-BWA are proposed; the rotated-interleaved channel assignment and the non-uniform channel assignment. According to statistical interference simulation analysis the proposed schemes are more efficient in suppressing interference, achieving higher capacity compared to existing schemes while incurring no further complexity. In addition, instead of exploiting the performance of CA and PA schemes independently a framework for a joint CA-PA consideration is presented, where for a particular CA scheme an optimized PA pattern is developed. Results show that this approach improves the CA-PA interoperability increasing the overall performance. The efficiency of the proposed schemes is investigated for both FDD and adaptive-TDD schemes and is verified for various sectorization, frequency re-use and terminal antenna directivity configurations to ensure compatibility with different deployment scenarios.

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 91%

See 1 more Smart Citation

Novel Channel and Polarization Assignment Schemes for 2–11 GHz Fixed–Broadband Wireless Access Networks

Sharif

2006

Wireless Pers Commun

“…An effective approach to mitigate this kind of interference is to apply a CA scheme that will determine the sector antenna orientation in a way to minimize the correlation of co-channel links among sectors. In this context, the Rotated -Interleaved Channel Assignment (RICA) scheme proves to be the most efficient, according to [4], [5] both for FDD and TDD F-BWA systems. RICA is presented in Figure 2, considering a quad-sectored cell F-BWA network layout and a frequency re-use factor, FR=1.…”

Section: A Rotated-interleaved Channel Assignmentmentioning

confidence: 99%

“…In this scope an approach that combines Channel Assignment (CA), [2], [4]- [5], and Antenna Arrays (AA), [6]- [7] is proposed. An effective CA scheme not only reduces overall CCI but also may allow for a simpler AA system.…”

Section: Introductionmentioning

confidence: 99%

Interference Mitigation in TDD Fixed Broadband Wireless Access Using Channel Assignment and Antenna Arrays

2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications

Sharif³

Self Cite

In Time Division Duplex (TDD) Fixed Broadband Wireless Access networks, co-channel interference that arises from the correlation of downlink and uplink signals in different sectors may considerably degrade the spectral efficiency. To overcome the complexity and costs of complete frame-TDD boundary synchronization in the network, a combined Channel Assignment (CA) and Antenna Array (AA) approach is proposed to mitigate interference. First a RotatedInterleaved CA (RICA) scheme is applied, which exploits sector antenna directivity to reject the majority of interferers by receiving them through the antenna side and back lobes. Combined with RICA, an AA system is used in the base station side to further reduce intersector interference during both transmission and reception phases. For the worst-case interference scenario an Unsynchronized TDD scheme, the proposed methodology achieves a 51.5% improvement in the average channel capacity while it considerably improves the uplink availability. An advantage of this approach is that it considers only lowcomplexity AA system configurations, thereby optimizing the corresponding cost.

A rotated-interleaved channel assignment scheme in adaptive TDD fixed-broadband wireless access

2005 IEEE International Conference on Personal Wireless Communications, 2005. ICPWC 2005.

Sharif³

et al.

The concept of channel assignment in Adaptive TDD (ATDD) Fixed Wireless Networks is addressed in this paper. A novel Rotatedinterleaved Channel Assignment (RICA) scheme is proposed that improves throughput, compared to existing schemes, by up to 9% inducing no further costs. Furthermore, the spectral efficiency between FDD and ATDD modes of operation is investigated considering the same network characteristics and RICA. It appears that according to the traffic asymmetry variations as expressed in the moving TDD boundary, the throughput performance of ATDD is from 2% to 14% less than that of FDD.