Coexistence issues for IEEE 802.22 WRAN and DVB-T2 networks

In this letter, we investigate the spectral efficiency of IEEE 802.22 wireless regional area network (WRAN) spectrum overlay when it is used in TV white space. Since 2004, when the FCC published the notice of proposed rule making 04-186 to make use of unused TV spectrum, the IEEE 802.22 working group has been standardizing specifications for WRAN operations. There have been a few papers investigating the spectral efficiency of this, but their analyses were limited to the cases for various guard distances between WRAN base stations. Since WRAN base station (BS) power for WRAN service may differ from country to country, it is important to analyze the spectral efficiency for various WRAN BS powers. In this letter, we analyze the spectral efficiency of WRAN spectrum overlay as a function of the power of WRAN BSs. The simulation results show that spectral efficiency decreases as the power of WRAN BSs and guard distances increase.

IEEE 802.22 is the cognitive radio-based first worldwide standard for wireless regional area network (WRAN). The primary objective of this standard is to provide broadband access to remote and rural areas. In these remote areas, a large number of vacant TV channels are available, known as white spaces. This standard allows broadband access to the users using these TV white spaces (TVWS). Also, much analog transmission has been moved towards digital transmission in UHF band so this situation has created a digital divide. In this paper, we proposed a novel scheme of simulation for the physical layer of IEEE 802.22 Wireless Regional Area Network (WRAN) with another cyclic prefix. In this paper, we have also demonstrated the effect of length of cyclic prefix in OFDM symbol on the BER performance of the physical layer of WRAN. We simulated the physical layer of WRAN with cyclic prefix 1/4 and 1/32 between successive OFDM symbols. We used convolution code with code rate 1/2 as FEC and evaluated the performance with BPSK, QPSK, and QAM-19 digital modulation schemes in Rayleigh fading condition in MATLAB. We concluded that the effect of ISI can be mitigated with cyclic prefix 1/32 for all three proposed modulation schemes and found that better BER performance in limited SNR. Also, the performance of BPSK with CP 1/32 is superior to QPSK and QAM-16 for CP of 1/4 as well as 1/32.

SummaryThe wireless regional area networks (WRANs) operates in the very high frequency and ultra high frequency television white space bands regulated by the IEEE 802.22 standard. The IEEE 802.22 standard supports Extensible Authentication Protocol (EAP)‐based authentication scheme. Due to the participation of a server and the information exchanged between a customer primes equipment and the secondary user base station, it takes around 50 ms to complete a complete EAP authentication that cannot be accepted in a handover procedure in WRANs. In this paper, we propose an EAP‐based proxy signature (EPS) handover authentication scheme for WRANs. The customer primes equipment and secondary user base station accomplish a handover authentication without entailing the server by using the proxy signature. Approved by the logic derivation by Burrows, Abadi, and Needham logic and formal verification by Automated Validation of Internet Security Protocols and Applications, we can conclude that the proposed EPS scheme can obtain mutual authentication and hold the key secrecy with a strong antiattack ability. Additionally, the performance of the EPS scheme in terms of the authentication delay has been investigated by simulation experiments with the results showing that the EPS scheme is much more efficient in terms of low computation delay and less communication resources required than the security scheme regulated in IEEE 802.22 standard.

When the great disaster strikes, it is most important for victims to receive and transmit appropriate information in order to evacuate immediately and to request for assistance and rescue. The Great East Japan Earthquake teaches us the importance of information communication technology (ICT) using wireless communication technology, e.g., television (TV), radio, the community wireless system for disaster, and mobile phone. However, after the disaster occurrence, particularly, mobile phones were left unusable for a long time due to network congestion, physical damage to base stations, and out-of-fuel of standby power systems. To combat these problems, the ICT services require more robustness, availability, flexibility, and redundancy. In this paper, we discuss the competence of IEEE standard 802.22-based wireless regional area network (WRAN) using television white space (TVWS) which can provide wide service area and utilize geographically or temporally unoccupied resource of TV frequency bands, although the frequency bands are allocated by regulatory domain. Furthermore, we introduce and evaluate a developed prototype of the WRAN equipment. The prototype provides point-to-multipoint service and throughput up to 12.2 Mbps in downstream (DS) and 9.5 Mbps in upstream (US).

IEEE 802.22 is a standardized WRAN (Wireless Regional Area Network) system that operates in TVWS (TV White Spaces) and aims to achieve an effective spectrum utilization. Since IEEE 802.22 offers excellent propagation characteristics in the UHF (Ultra High Frequency) band, it is expected to support a cost-effective wireless communication system in rural areas. To provide a long-distance wireless communication, it is important for the receiver design to compensate a multipath fading attributed to large differences in path lengths, while existing multipath fading channel profiles applicable to IEEE 802.22 has generalization and statistical limitations. To generally and stochastically reproduce the multipath propagation characteristics in an actual wide area environment, an algorithm to obtain a statistical channel model extracted from the field experiment data is required. In this study, we develop a novel channel modeling algorithm based on the conventional S-V (Saleh-Valenzuela) modeling algorithm that offers an approach to model and reproduce the multipath characteristics in an actual environment. The proposed channel modeling algorithm applies a dynamic GEV (Generalized Extreme Value) distribution fitting for the amplitude fluctuation of individual arrival cluster. We also evaluate the channel reproduction performance of the proposed algorithm by computer simulation using channel modeling factors calculated from the experiment result with a FE (Fading Emulator). As a result, by applying the proposed algorithm, the multipath fading characteristics measured in the experiment can be modeled, and its reproducibility is confirmed with regard to relative path power distribution, rms delay spread distribution, and BER characteristics.

A two-hop wireless regional area network (WRAN) providing monitoring services using Television White Space (TVWS), i.e., IEEE p802.22b, is now under development. A great number of subscriber customer-premises equipments (S-CPEs) may be connected to a base station with relaying of a relay CPE (R-CPE)

IEEE 802.22 wireless regional area network (WRAN) is an emerging cognitive radio-based system. One of the major challenges for WRANs is how to efficiently schedule both channel sensing and data transmission for multiple adjacent WRAN cells. This challenge is known as coexistence problem. In this paper, we propose four schemes that aim at reducing the coexistence-problem effect. These schemes are based on a well-known operation mode of IEEE 802.22, namely dynamic frequency hopping (DFH). The first and second schemes are based on using omni-directional antennas at the base stations (BSs), whereas the BSs in the other two schemes use directional antennas. The first scheme, coined fixed-scheduling DFH (FDFH), bases upon a fixed scheduling of working channels for adjacent WRAN cells. The second scheme, called cooperative DFH (CDFH), cooperatively selects working channels. The third scheme, namely sectoral DFH (SDFH), is proposed to reduce the coordination overhead of CDFH via dividing a WRAN cell into sectors to decrease the chances of collisions between adjacent cells. Finally, we integrate FDFH and SDFH into a new scheme, called fixed-scheduling sectoral DFH (FSDFH), which exploits the advantages of both schemes with no additional overhead. Computer simulations are used to demonstrate the performance gain of the proposed schemes.

Unlicensed Operations in the Lower Spectrum Bands: Why is No One Using the TV White Space and What Does That Mean for the FCCCs Order on the 600 MHz Guard Bands?

The regulatory framework for secondary utilization of TV white spaces (TVWS) is well underway in the United Kingdom, while important steps in this direction are taken within the European Union and elsewhere. Mobile network operators are interested in the use of TVWS for cellular extension and rural access, where TVWS is seen as a significant new opportunity for operators to provide new wireless services. The government's plan to close the digital divide between the urban and rural communities has motivated the efforts to develop Wi-Fi like operation in TVWS for better coverage in rural areas. The IEEE currently has a working group developing 802.11af amendment which will allow for WLAN operations in the TVWS. This paper presents a quantitative analysis of downlink throughput performance of IEEE802.11af, also known as White-Fi in a rural environment while taking into account realistic modelling of TV channel availability, wireless channel, AP density, and the effect of co-channel interference caused by secondary APs and DVB-T transmitters. The paper shows that the low operating frequency of White-Fi offers a wide coverage in a rural environment, where there is limited cellular coverage due to the cost-inefficiency of base stations deployment. The presented results also show that there are more available TVWS channels and less co-channel interferers in a rural environment, resulting in a significant throughput performance even in high mobility if suitable channel estimation is considered, making it ideal for vehicular communications with White-Fi.

Studies carried out across the world have revealed underutilization of the UHF/VHF TV bands. Standards and required equipment to opportunistically harness these TV whitespaces have evolved in recent past. Progress is also being made in India with respect to the study of the TV band spectral occupancies and it potential usage. One of the most attractive uses of TV whitespace in India would be for last mile digital connectivity for rural areas. Fiber has reached up to major parts of taluk levels in India and to extend connectivity to the villages, a technology is needed that is suitable for long distance broadband communication. The VHF/ UHF bands are known for their excellent propagation characteristics. The preferred technology for data communication over this band is called super Wi-Fi defined by standard IEEE 802.11af. However, the potential interference effects of the data transmissions in these bands on any future Digital TV transmission is a matter of concern for licensing authorities. In this paper, we present the feasibility study of data transmission in the TV whitespace. The contributions of the paper are two fold: i). Study of spectral occupancy across the UHF and VHF band in Bangalore. ii) Investigation of interference patterns between digital video transmission and Wi-Fi.

The IEEE 802.22 is a standard for wireless regional area networks to opportunistically operate in TV bands; however, sharing TV White Space (TVWS) spectrum creates a problem of coexistence because no mechanism is defined for coordinating channel usage among secondary networks. We propose a White Space Resource Sharing mechanism (WSRS) for fixed secondary and mobile IEEE 802.22 networks to improve network coexistence and spectrum efficiency. Based on power control and channel allocation, our mechanism allows the TVWS system to serve vehicular networks in scenarios where there are active secondary fixed networks and no more TVWS channels available for opportunistic usage. Unlike state-of-the-art mechanisms for coexistence in TVWS spectrum, our mechanism allocates resources to vehicles even when the density of fixed nodes and the transmission power of the fixed network cause high interference to the vehicular network. Our results show the offered channel capacity increases up to 50% using the proposed WSRS mechanism compared to the recent IEEE 802.22 standard that does not have a defined TVWS channel sharing mechanism. Furthermore, our WSRS mechanism implements a strategy to protect the fixed secondary network from interference caused by vehicular transmissions while promoting fair usage for both secondary networks.

Summary form only given. Broadband wireless access is the third wireless revolution; the broadcast nature of wireless transmission offers ubiquity and immediate access for both fixed and mobile users, clearly a vital element of next- generation quadruple play services. Unlike wired access, a large portion of the deployment costs is incurred only when a subscriber signs up for service. An increasing number of municipal governments around the world are financing the deployment of multihop wireless networks with the overall aim of providing ubiquitous Internet access and enhanced public services. This tutorial will provide a comparative assessment of the key issues and technologies underpinning promising broadband wireless access solutions. Key topics include licensed and unlicensed spectrum consideration; reliable physical layer transmission using multiple antennas; multichannel medium access protocols with QoS provisioning; wireless access topologies: point-to-point, point-to-multipoint, peer- to-peer multihop (mesh); wireless multimedia services: wireless IP-TV, wireless VoIP; mobility; cognitive radio technologies; advanced wireless security; wireless/wireline integration

One of the many standards developed recently for television white space operation is the IEEE 802.11af wireless LAN in TV white space. This white space device as a secondary user (SU) must not cause damaging interference to an incumbent primary user(PU) such as the ISDB-T digital TV service and even to an existing Analog TV Broadcast. To ensure interference-free coexistence, a keep-out distance, d <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</inf> , between the white space device (WSD) transmitter and the PU within the licensed TV service contour should be strictly observed. However, it is important that this d <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</inf> must neither be overestimated nor underestimated. In this paper, co-channel d <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</inf> between IEEE S02.11af and the ISDB – T DTV and Analog service contours using primarily ITU-R P.1546-6 and ITU–R P.1411-9 recommendations was computed and compared for the eleven analog and digital channels operating in Cebu province, Philippines. Experimental tests conducted show that analog and digital TV broadcast channels are aptly protected from co-channel interference emanating from IEEE 802.11af secondary white space devices operating within its service contour. Interestingly, the study also shows that a pair of IEEE 802.11af devices can establish connectivity within the ITU-R P.1546-based keep-out distance without causing interference to ATV and DTV services.

The explosive growth of capacity-hungry wireless services are presenting challenges to the scarce spectrum resource. Operating LTE systems on TV white space may meet the capacity demand due to the good propagation characteristic. However, according to the decision on World Radiocommunication Conference 2012, TV white space is unable to be used by LTE systems exclusively in the near further in China. Cognitive technologies throw light on sharing TV white space between LTE and TV broadcasting systems. Taking 470– 806 MHz band as an example, the availability of deploying LTE systems on TV white spaces in China is studied in this paper. Firstly, the separation distance from LTE stations to the edge of TV coverage area is calculated. Then, the inter-site distance between TV and LTE stations are figured out using the separation distance and TV coverage radius. Combining the theoretical calculation with the deployment information of both analog and digital TV stations stored in the national station database, simulation results on the capacity distribution of cognitive LTE system in typical cities are given. The simulation results inferred that approximately 67% of TV channels are unused averaged over the cities. This result confirms quantitatively the often-stated expectation that white spaces can be shared by LTE systems to meet the capacity demand as well as improve the spectrum efficiency.

본 논문에서는 인지 무선 기술을 기반으로 한 주파수 공동 사용 기술을 적용하는 대역으로 주목을 받고 있는 TVWS 대역에 관하여 국내 기술 기준을 제정할 경우에 기존 서비스 보호, TVBD의 기술적인 요구 사항 및 TV 대역 DB 구축 관점에서 고려하여야할 기술적인 사항들을 제안한다. 제안한 사항들의 기본 개념은 기존 서비스인 DTV 및 무선 마이크를 절대적으로 보호해야 한다는 점을 기반으로 하고 있다. 외국의 기술 규격을 분석한 결과, 영국의 Ofcom 접근 방법은 매번 채널 및 출력 선정 알고리즘을 계산해야 되므로 TV 대역 DB에 상당한 부하가 걸릴 수 있는 반면에 미국의 FCC 접근 방법은 상대적으로 신속한 채널 목록과 송신 출력을 지정해 줄 수 있는 장점이 있음을 알 수 있었다. In this paper, we propose the technical considerations for the rules on television white space(TVWS), that becomes a center of public notice, in terms of incumbent services protection, technical requirements of television band devices (TVBDs) and administration of TV band databases. The basic idea behind the proposed method is based on the perfect protection of incumbent services such as digital television and wireless microphone. It has been found that FCC's approach has the advantage that a list of available channels and transmission power are provided for TVBDs faster than Ofcom's approach that requires DB to perform the algorithm for determining frequencies and transmission power for TVBDs everytime DB is asked from TVBDs.