In this paper, we explained the necessity of inter-piconet communications in a WPAN. Inter-piconet communications can be realized by utilizing relays. We further showed that relay selection impacts on the system performance. Based on our observation, we designed a joint relay selection and scheduling algorithm which can deal with both intra-piconet and inter-piconet flows. The joint algorithm consists of two phases: the first phase is to schedule intra-piconet flows; the second phase is to schedule inter-piconet flows. Relay candidates are screened through the verification of
“interference-free” and the derivation of “concurrence-restricted extent”. When multiple relay candidates are available, “concurrence index” is used to designate the most suitable relay.
We conducted simulations to evaluate the performance of our algorithm. The simulation results showed that, compared with CTAP-minimized with randomly multiple relays scheduling algorithm, our algorithm achieves 20%-40% improvement in utilized channel time, system throughput, and spatial channel reuse degree.
We design an algorithm including the relay selection and inter-piconet flows scheduling to minimize the CTAP extension and improve the system throughput in IEEE 802.15.3c networks. The flows we consider here need better QoS. They request sufficient resource, and PNC guarantees different CTA duration to serve those flows.
However, in practical, the 802.15.3c networks are also applied to real-time transmission. In this application, the flows requests are usually best effort. We have to design an algorithm which considers the service type of saturated flow request or real-time flow request. We assume the CTAP duration and the number of time slot in CTAP are fixed, and our goal is to divide the CTAP into several CTAs with the same duration and group all requested flows (intra- and inter-piconet flows) to concurrently
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transmit in those CTAs. Our challenge is how to decide the bottleneck piconet in which each flow can obtain the less resource and limit the inter-piconet flows’
transmission. The relay selection is important because the best relay selection can let most flows without interference transmit simultaneously. If less groups share a superframe, the groups can get more resource. The basic design concept is to maximize the group members and minimize the group number. In general, the protocol components must contain the relay selection scheme, grouping algorithm, and bottleneck piconet detection.
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References
[1] "IEEE Standard for Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements Part 15.3: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for High Rate Wireless Personal Area Networks (WPANs) Amendment 1: MAC Sublayer," IEEE Std 802.15.3b-2005 (Amendment to IEEE Std 802.15.3-2003), pp. 0_1-146, 2006.
[2] "IEEE Draft Amendment to IEEE Standard for Information technology--telecommunications and information exchange between systems--Local and metropolitan area networks--Specific requirements--Part 15.3:
Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for High Rate Wireless Personal Area Networks (WPANs):
Amendment 2: Millimeter-wave based Alternative Physical Layer Extension,"
IEEE Unapproved Draft Std P802.15.3c/D08, March 2009
[3] IEEE 802.11 WLAN Very High Throughput in 60 GHz Task Group ad (TGad), http://www.ieee802.org/11/, Online Link.
[4] F. daCosta, Dynamic Beacon Alignment in Simultaneously Operating Piconets (SOP) Using the Heart Beat Approach, IEEE Std. P802.15- 04/135r0, March 2004.
[5] Ming-Pei Hsu and His-Lu Chao, "Scheduling with Reusability Improvement for Millimeter Wave Based Wireless Personal Area Networks," Communications (ICC), 2010 IEEE International Conference on, vol., no., pp.1-5, 23-27 May 2010 [6] Hsi-Lu Chao and Ming-Pei Hsu, “CTAP-Minimized Scheduling algorithm for
Millimeter Wave Based Wireless Personal Area Networks,” accepted by Vehicular Technology, IEEE Transactions
36
[7] J.Y. Wang, Z. Lan, et.al., “Robust and highly efficient beamforming procedures for 60GHz WPAN,” IEEE 802.15-08-0190-003c, November 2008.
[8] Peng Xue, Peng Gong, Duk Kyung Kim, "Enhanced IEEE 802.15.3 MAC Protocol for Efficient Support of Multiple Simultaneously Operating Piconets,"
Vehicular Technology, IEEE Transactions on, vol.57, no.4, pp.2548-2559, July 2008
[9] L. X. Cai., Lin Cai, Xuemin Shen, and J. W. Mark, “Efficient Resource Management for mmWave WPANs,” Wireless Communications and Networking Conference, 2007. WCNC 2007. IEEE, vol., no., pp.3816-3821, 11-15 March 2007
[10] L. X. Cai, Lin Cai, Xuemin Shen, and Mark J. W., ”REX: A andomized ErXclusive region based scheduling scheme for mmWave WPANs with directional antenna,” Wireless Communications, IEEE Transactions on, vol.9, no.1, pp.113-121, January 2010
[11] Zhou Lan, Chin-Sean Sum, Junyi Wang, Baykas T., Kojima F., Nakase H., Harada H., “Relay with Deflection Routing for Effective Throughput Improvement in Gbps Millimeter-wave WPAN Systems,” Selected Areas in Communications, IEEE Journal on, Vol. 27, no.8, pp.1453-1465, October 2009 [12] Zhou Lan, Junyi Wang, Jing Gao, Chin-Sean Sum, Fumihide Kojima, Tuncer
Baykas, Hiroshi Harada, Shuzo Kato, “Directional Relay with Spatial Time Slot Scheduling for mmWave WPAN Systems,” Vehicular Technology Conference, 2010. VTC Spring 2010. IEEE, vol., no., pp.1-5, 16-19 May 2010
[13] Chin-Sean Sum, Zhou Lan, Ryuhei Funada, Junyi Wang, Tuncer Baykas, Mohammad Azizur Rahman, and Hiroshi Harada, “Virtual Time-Slot Allocation Scheme for Throughput Enhancement in a Millimeter-Wave Multi-Gbps WPAN
37
System,” Selected Areas in Communications, IEEE Journal on, Vol. 27, no.8, pp.1379-1389, October 2009
[14] Hang Su and Xi Zhang, “Joint Link Scheduling and Routing for Directional-Antenna Based 60 GHz Wireless Mesh Networks,” Global Telecommunications Conference, 2009. IEEE GLOBECOM’09, Vol., no., pp.1-6, 30 November 4 December 2009
[15] Chang Woo Pyo and Hiroshi Harada, “Throughput analysis and improvement of hybrid multiple access in IEEE 802.15.3c mm-wave WPAN,” Selected Areas in Communications, IEEE Journal on, vol. 27, Issue 8, pp.1414-1424, 2009