PPME - New priority MAC protocol for multi event wireless sensor network

In multievent wireless sensor networks, different priority level events can appear at the same time and require different QoS (Quality of Service) provision based on various priority levels. So, in this paper, we propose a new MAC protocol using beacon and CSMA p-persistent varied by packet priority levels to reduce collisions for different priority level packets in multiple event wireless sensor networks.

Kỹ thuật điều khiển & Điện tử PPME - NEW PRIORITY MAC PROTOCOL FOR MULTI-EVENT WIRELESS SENSOR NETWORK Nguyen Thi Thu Hang*, Nguyen Chien Trinh, Nguyen Tien Ban Abstract: In multievent wireless sensor networks, different priority level events can appear at the same time and require different QoS (Quality of Service) provision based on various priority levels So, in this paper, we propose a new MAC protocol using beacon and CSMA p-persistent varied by packet priority levels to reduce collisions for different priority level packets in multiple event wireless sensor networks Simulation results show that our proposed protocol significantly reduces packet latency for all four priority level packets and saves more energy than QAEE and MPQ MAC protocols Moreover, the protocol keeps high packet success rate compared to the other two protocols Keywords: Priority MAC, CSMA p-persistent, Multievent, Wireless sensor network INTRODUCTION In some wireless sensor networks (WSN), different types of events can appear at the same time Higher priority levels are mostly assigned to the important or emergency events such as wildfires in forest fire alarm systems, earhquake warning or first aid for stroke patients [1-3] Lower priority levels are mainly set for normal events as regular measurement of temperature, wind power, water level or heartbeat High priority events often require higher quality of service than normal ones such as more real-time, higher reliability and also require energy consumption efficiently, especially in WSN with the limitation of power and processing capacity [4-7] To meet these complex requirements of QoS and energy efficiency, there are many proposed QoS solutions for wireless sensor networks using MAC technology SMAC [8] and TMAC [9] focus on energy saving in networking, RI-MAC [10] improves network performance as packet delay and transmission rate, ERI-MAC is the protocol initiated by the receiver and uses the technique of multiplexing small packets into large packets before transmission for energy saving [11], PQMAC considers packet priority in the network but requires synchronization between nodes [12], QAEE also considers packet priority and has two priority packet levels that are high and low [13], and MPQ takes into account four packet priority levels [14] The above solutions have limitation in meeting multi-priority requirements or if they have already consider different packet priority, priority packets still have to wait for a certain period of time until the end of the disputed window to be transmitted Especially in emergency cases, there will be multiple conflicting packets which reduce the packet success rate as well as prolong the packet delay for retransmission after the collision In order to solve the problem of priority transmission of concurrent important packet types, ensuring small delay and good packet success rate, in this paper we propose the Priority MAC protocol for Multi-Event wireless sensor network which combines Beacon and priority MAC mechanisms (PMME) The contributions of the paper are as follows: Propose a combination of beacon mechanism and a novel CSMA p-persistent mechanism varied by different packet priority levels Implement the proposed PMME protocol in Castalia simulation to evaluate and compare with other two MAC protocols (QAEE and MPQ) on the ability to meet the multi QoS requirements of four different packet priority levels in a multi-event wireless sensor network 12 N T T Hang, N C Trinh, N T Ban, “PPME – new priority MAC … sensor network.” Nghiên cứu khoa học công nghệ The paper is organized as follows: Section describes the operation mechanism and analyzes the advantages and disadvantages of QAEE and MPQ protocols that consider the priority of packets Section introduces the proposed PMME MAC protocol with two enhancements The evaluation of PMME based on computer simulation is presented in Section Finally the last section is the summarization and our future research work RELATED WORK Several research works have been considered to ensure QoS for multi-priority wireless sensor networks such as PQMAC [12], QAEE [13], and MPQ [14] PQMAC (Priority-based QoS) considers four packet priority levels in the network but requires synchronization between nodes [12] and the packet delay is still higher than the requirement of realtime application Figure Description of the operation of QAEE-MAC protocol QAEE is the protocol that allows the receiver to initiate communication [13] It considers two priority levels of packets and allows high priority packets to be transmitted faster than low priority ones In this protocol, receiver node will wake up periodically to receive packets sent from the sender After waking up, the node will listen to the environment for a guaranteed period of time Tg and then sends Wakeup-Beacon to notify senders After transmitting the Wakeup-Beacon, the receiver will wait for a while to receive the all Tx-Beacons (which adds the priority field) of senders The senders will insert the packet priority bit and the Network Allocation Vector (NAV) field in the TxBeacon Then, the senders will wait for the Rx-Beacon with NAV field from the receiver The receiver will receive multiple Tx-Beacons with different priority levels in a period of time Tw and select one sender based on the highest packet priority It then propagates the Rx-Beacon carrying the address of the selected sender Based on receiving this Rx- Tạp chí Nghiên cứu KH&CN quân sự, Số 59, 02 - 2019 13 Kỹ thuật điều khiển & Điện tử Beacon, the selected sender will be allowed to send data while other senders will not be active during this time In the aftermath of the competition, senders with untransmitted data will wake up and continue randomly competing as before Figure describes QAEE communication operation in which SIFS (Short Interframe Space) is the required interval for processing a packet and switching the radio state of the sensor node QAEE has some disadvantages First, it considers only two priority levels as high (1) and low (0) Second, the receiver node must wait until it receives the entire Tx-Beacons from the sending nodes and then sends the Rx-Beacon to all senders This means that even if the receiver has received the highest priority Tx-Beacon then it still has to wait until Tw runs out Therefore, the higher priority sender still has to wait and other sending nodes consume energy during idle listening time for Rx-Beacon MPQ has improved over QAEE by considering four different priority levels (Table 1) and significantly reduces the latency for the highest priority packets by accepting first TxBeacon with the highest priority and then sends an Rx-Beacon acknowledgment to the selected sender without waiting until Tw runs out [14] If there is no highest priority packet arrives before Tw runs out, packets of lower priority still have to wait until Tw expires The MPQ protocol uses CSMA p-persistent mechanism with p is inversely proportional to the number of senders ns , this mechanism spreads Tx-Beacon frames from ns senders evenly to reduce collision Table Different levels of packet priority [15] Data Category Priority Urgent Most Important Important Normal The MPQ protocol uses the general format of IEEE 802.15.4 frame for Wakeup-Beacon, Tx-Beacon, and Rx-Beacon frames with some special fields highlighted in Figure SA is the source address of the packet to be sent to the destination address DA In the Wakeup-Beacon, SA is the receiver’s address, this beacon is used to broadcast to the surrounding environment, so there is no specific destination address DA In the TxBeacon, SA is the address of the sender has sensor data to be sent, the DA is the receiver node’s address, and the priority is the priority of the sensor data to be sent In the RxBeacon, SA is the address of the node that wants to receive data, the DA is the sender node’s address that has been selected by the receiver However, the MPQ protocol still has some limitations First, only the highest priority packets will be processed earlier, while the lower priority packets still have to wait until Tw expires to be considered for delivery Thus, the nodes not have the highest priority packets also have to spend time waiting for the Rx-Beacon Secondly, assigning p values is rigid and unrealistic which requires receivers in the network have to know exactly the number of competing senders With the remaining shortcomings of the QAEE and MPQ protocols, further improvements to the MAC protocols should be addressed to further improve WSN performance 14 N T T Hang, N C Trinh, N T Ban, “PPME – new priority MAC … sensor network.” Nghiên cứu khoa học công nghệ FC SA FCS FC SA DA Priority FC SA DA NAV Wakeup-Beacon NAV FCS FCS Tx-Beacon Rx-Beacon FC: Frame Control FCS: Frame Check Sequence SA: Source Address DA: Destination Address NAV: Network Allocation Vector Figure Frame format of all Beacons [14] PROPOSED SOLUTION In order to achieve the quality of service required by packets of different priority levels, our proposed MAC protocol in the paper has two variations compared to the MPQ protocols Firstly, in order to prioritize data packets according to the priority level of the packet, the proposed MAC protocol allows the sending nodes to send a Tx-Beacon with the sending frequency proportional to the priority level of packet Secondly, the receiver shortens the waiting time for sending Rx-Beacon When the receiver receives the first Tx-Beacon from any sending node, it sends the Rx-Beacon to the first sender node This Rx-Beacon also informs other sender nodes to sleep during the transmitting data of the selected sender Figure describes the proposed PMME operation with two enhancements: the CSMA p-persistent mechanism, which adapts to the priority level of the packet, and the earliest Tx-Beacon accepting mechanism 3.1 CSMA p-persistent mechanism with p varied by the priority level To prioritize packets, in the PMME protocol, a new CSMA p-persistent mechanism is applied, Tx-Beacon is sent from sender with p varied by priority level (Figure 4) With this mechanism, if a sender receives its Rx-Beacon (allowing it to send data frame), first, it listens to the medium (or check the state of the medium) before deciding to send data frame or not Second, if the sender finds the medium is idle it follows these steps: With probability p , the sender sends its frame The value p is varied by the priority level, the higher the priority level, the larger the p (largest p is 1, smallest p is 0) In our proposal, there are two different types of the value p: linear and non linear a) For linear value, sender i th will have its value pni as pni  i n (1) j j 1 Tạp chí Nghiên cứu KH&CN quân sự, Số 59, 02 - 2019 15 Kỹ thuật điều khiển & Điện tử where n is the number of priority levels b) For non linear value, sender i th will have its value pai ,n as a i 1 pai ,n  (2) n a j 1 j 1 where a is the distinguishing base, and n is the number of priority levels Of cource, the summarization of all senders’ p i must equal (means one hundred per cent) as follows: n n  pi  (linear i 1 n  pni  or non linear i 1 i a ,n p  1) (3) i 1 Tw Accept earliest Tx-Beacon, no need to wait until Tw expired Receiver Tg TX: Wakeup Beacon RX: TX: Tx Rx Beacon SIFS Beacon (to N1) RX: DATA SIFS TX: ACK Wakeup Sender (N1) Listening RX: Wakeup Beacon Packet Generation Sender (N2) Listening RX: Rx Beacon SIFS (to N1) TX: DATA RX: ACK Time slot changed by priority level RX: Wakeup Beacon Packet Generation TX: Tx Beacon RX: Rx Beacon (to N1) Sleep, NAV+random time considering priority level TX: Transmit RX: Receive Figure Description of PMME operation With probability q   p , the sender waits for the beginning of the next time slot and checks the state of the medium again a If the medium is idle, it goes to step b If the medium is busy, it goes to step 16 N T T Hang, N C Trinh, N T Ban, “PPME – new priority MAC … sensor network.” Nghiên cứu khoa học công nghệ Wait for CCA check delay Sense the medium Busy Idle Wait for a time slot t prand ≤ pn N (pn ~ priority level) Y Send the frame Figure CSMA p-persistent in PMME The Tx-Beacon of a packet with higher priority level will have more chance to appear than the Tx-Beacon of a packet of the lower priority level, so that the accepting rate of the higher priority level Tx-Beacon would be higher than the lower one with limited times of retransmission 3.2 The earliest Tx-Beacon accepting mechanism To reduce the waiting time in the collising window after a sender sending WakeupBeacon, the PMME protocol uses the earliest Tx-Beacon accepting mechanism by sending Rx-Beacon right after receiving the first Tx-Beacon This Rx-Beacon also announces all other senders not sending their frames during the NAV time By doing so, our protocol will shorten the waiting time comparing to Tw of QAEE and MPQ protocols, the earlier sending Rx-Beacon will also help other senders know to avoid sending their frames and not make the collision in the following NAV time, neither waste the energy to sense the medium or send frames and make the collision become worst PERFORMANCE EVALUATION This part introduces the simulation results for evaluating, comparing multi-event wireless sensor network performance using the proposed PMME, QAEE and MPQ protocols based on Castalia 3.3 simulation [16] and OMNeT ++ 4.6 [17] using the CC2420 transceiver standard [18] Tạp chí Nghiên cứu KH&CN quân sự, Số 59, 02 - 2019 17 Kỹ thuật điều khiển & Điện tử 4.1 Simulation Parameters Table Simulation Parameters for PMME Parameter Network size Number of concurrent sender nodes Senders’ positions Bandwidth Frequency SIFS Radio Wakeup-Beacon size Tx-Beacon size Rx-Beacon size MAC overhead Maximum buffer unit Listen interval Retry limit Application header DATA packet size ACK packet size CCA Check Delay Slot time Physical frame overhead Value 10m x 10m 1-10 Random 250kb/s 2.4GHz 0.192ms CC2420 bytes 14 bytes 13 bytes 11 bytes 32 packets 17ms 10 bytes 28 bytes 11 bytes 0.128ms 0.32ms bytes 5ms Tw 6,7ms Tg a n packet/s Packet rate Table shows the main parameters in PMME simulation Sensor nodes are randomly distributed in the sensor field, at one time there would be to 10 sender nodes sending data, one sink is in the center Each sender node sends data packets at a rate of packet per second, with equal packets of different types Performance parameters are evaluated in our simulation:  Average packet delay: The packet delay is an expression of how much time it takes for a packet of data to get from the source node to the destination node There are several contributing sources to the delay encountered in transmitting a packet For all three protocols, they are propagation delay, the time the sender node has a packet wait for the Wakeup-Beacon, time to send Tx-Beacon, time to wait and receive the corresponding Rx-Beacon (this time can be extended by the NAV if it is not the selected node to send data packet), bandwidth delay (the time to send the packet data over a channel with limitted bandwidth) and other status transition times Average packet delay is the averate delay of all packets received by the receiver - Average packet delay Davr formula is calculated as follows: N D i Davr  18 i 1 N (4) N T T Hang, N C Trinh, N T Ban, “PPME – new priority MAC … sensor network.” Nghiên cứu khoa học công nghệ where N , Di are the total number of received packets and the delay of the i th received packet  Packet success rate (PSR): It is a ratio of the total number of packets received at the destination node N R (excluding duplicate packets) to the total packets sent from all sender nodes N S PSR   NR 100% NS (5) Energy Efficiency: It is considered as the inversion of the average power consumption for successfully transmitting a data bit (μj/bit) The less energy consumed, the higher the efficiency o The formula for calculating average energy consumption is as follows: E o ET N R  DS (6) Where ET , N R , and DS are the total power consumption, the total number of packets received, and the packet size in bits respectedly Total energy consumption is calculated as: m ET   Pk  tk (7) k 1 where m represents the number of states, k is the radio status (four states: state of play, state of reception, state of hearing, and state of sleep) Pk is the power consumption at state k and tk is the lifetime of the state k 4.2 Result analyses In this section, simulation results show that our PMME could adapt to the different QoS requirements of multiple event types especially with lower delay for all types of packets 4.2.1 Average packet delay Average packet delay is shown in Figure and Figure with packet sending rate of packet per second and maxTxRetries = 10, n  , and a  It can be seen that when the number of sending node increases, packet delay will be higher because many packages are sent at the same time and cause a collision QAEE uses Tw to be able to receive multiple requests at the same time and then sort the requests in order of priority level, then accepts the highest priority packets, so it will take more time to receive all the requests Since the packets compete for sending packets, there will be a collision that results in the retransmission of these packets And since no priority time is given for sender nodes to send Tx-Beacons, the probability of collision is high even at the next sending cycle With the proposed PMME solution, receiving the first request would greatly reduce the delay compared to QAEE and MPQ, and using the p-persistent collision avoidance mechanism would help to disperse the Tx-Beacon The PMME energy efficiency increases because Tạp chí Nghiên cứu KH&CN quân sự, Số 59, 02 - 2019 19 Kỹ thuật điều khiển & Điện tử this protocol avoids sending many repeated Tx-Beacons before the actual data packet is transmitted Figure Comparing the average package latency for all types of packages Figure Average packet delay using the PMME protocol versus using the QAEE and MPQ protocols However, the influence of maxTxRetries, after trying to send Tx-Beacon to the maximum retry number, the data packet will be destroyed On the other side, the packet delay will only count for the received packets, thus reducing the degree of differentiation of packet types when the number of sending nodes increases In addition, it can be seen 20 N T T Hang, N C Trinh, N T Ban, “PPME – new priority MAC … sensor network.” Nghiên cứu khoa học công nghệ that the delays of different priority packages of QAEE and MPQ not significantly differ from each other and from the PMME priority packets when the number of nodes is small The QAEE and MPQ assume that p is the inversion of the number of sender nodes, when the number of send nodes is 1, p is always and the Tx-Beacon is not delayed if it knows that the medium is idle, while the PMME does not distinguish the number of sender nodes, and there would always be delay time for Tx-Beacon to be sent even when the medium is idle In fact, it is impossible to know exactly the number of nodes that send data simultaneously at a time so the assumption of PMME is more reasonable 4.2.2 Packet delay of different priority levels a) Linear p, n=4 b) Nonlinear p, a=3, n=4 Figure Average packet delay using the PMME protocol with priority levels Packet delay according to PMME packet priority is shown in Figure with maxTxRetries = 10, number of senders is from to 10 In order to be able to perform a different priority mechanism, the scenario selects linear type with pni  i n and none j j 1 Tạp chí Nghiên cứu KH&CN quân sự, Số 59, 02 - 2019 21 Kỹ thuật điều khiển & Điện tử a i 1 In specific cases with n  , then p14  , 10 p42  0, , p43  0,3 and p44  0, For nonlinear type, n  , a  then p3,4  , 40 linear type for p with pai ,n  n a j 1 j 1 p3,4  27 , p3,4 , and p3,4   40 40 40 As shows in Figure 7, the higher the priority level of a packet, the smaller the packet delay This effect is due to the p-persistent mechanism with p varied by the priority level Higher priority packets are delayed less than lower priority ones, combined with the earliest Tx-Beacon receiving mechanism, the average packet delay is significantly reduced than packets sent using QAEE and MPQ protocols The higher the number of concurrent sender nodes, the higher the difference of the packet delay The higher the value of a , the better the delay for high priority level packets 4.2.3 Packet success rate Figure The packet success rate with QAEE, MPQ, and PMME protocols with maxTxRetries = 10 Figure shows the packet success rate in a network using QAEE, MPQ, and PMME protocols with the maximum number of retransmission TxRetries of 10, and different number of sensor nodes sending data simultaneously It can be seen that the proposed MAC protocol PMME helps the network to operate more efficiently with higher packet success rate than QAEE and MPQ The p-persistent mechanisms helps the network avoid unnecessary collision by using the probable delay mechanism As the number of concurrent sending nodes increases, the level of conflict of QAEE and MPQ increases, resulting in lower packet success rate Because the number of retransmission is limited, and the packet lifetime is also limited, many data packets could not arrive at the receiver PMME reduces collision due to the premature delivery of the Rx-Beacon, so it also helps packets to be forwarded to the destination earlier The Rx-Beacon is to confirm the selected sender node prematurely, other nodes will stop sending Tx-Beacon and go to sleep until next Wakeup-Beacon is sent from the receiver, PMME has improved the packet transmission efficiency, helping to increase the packet success rate with limited maxTxRetries much better than QAEE and MPQ 22 N T T Hang, N C Trinh, N T Ban, “PPME – new priority MAC … sensor network.” Nghiên cứu khoa học công nghệ 4.2.4 Energy Efficiency Figure shows the average power consumption for successfully transmitting a data bit with three corresponding MAC protocols: QAEE, MPQ, and PMME, and maxTxRetries=10 It can be seen that as the number of sending nodes increases, the average power consumption using the QAEE protocol increases rapidly while with MPQ and PMME protocols, the average power consumption increases very slowly This is because the PMME accepts Rx-Beacon as soon as the first Tx-Beacon is received This reduces the ineffectual time of Tw and thus saves energy for the network Figure Average power consumption for successfully transmitting a data bit for QAEE, MPQ and PMME protocols with maxTxRetries = 10 CONCLUSION AND FUTURE WORK In this paper, we propose a solution to improve multi-event wireless sensor network performance using the novel PMME priority MAC protocol PMME uses two enhancements to improve WSN performance against two previous QAEE and MPQ priority MAC protocols: the CSMA p-persistent mechanism, which adapts to the priority level of the packet to differentiate MAC delay for different priority packets, and the earliest Tx-Beacon accepting mechanism to reduce delay for all packet types and to save ineffectual energy for sender nodes waiting to be selected to transmit data packets Simulations have been performed with different scenarios of the number of nodes, the rate of sending packets is packet per second and the maximum number of retransmission maxTxRetries is 10 The simulation results show that the PMME protocol has significantly reduced the average packet delay for all packet types, and differentiates the packet delay by priority levels: the higher the priority level, the lower the packet delay Beside that, PMME achieves high packet success rate and reduces the energy consumption per data bit than QAEE and MPQ In the future, we will continue to further improving the multi-event wireless sensor network performance considering energy rechargeability Our future proposed solution will combine packet priority awareness in the MAC layer with energy awareness routing for better practical application Acknowledgement: This work is partly supported by Motorola Solutions Foundation under Motorola scholarship and research funding program for ICT education Tạp chí Nghiên cứu KH&CN quân sự, Số 59, 02 - 2019 23 Kỹ thuật điều khiển & Điện tử REFERENCES [1] S Abdullah, S Bertalan, S Masar, A Coskun, I Castle, “A wireless sensor network for early forest fire detection and monitoring as a decision factor in the context of a complex integrated emergency response system,” in IEEE Workshop EESMS, Milan, Italy, Jul 24-25, 2017 DOI: 10.1109/ EESMS.2017.8052688 [2] Alphonsa A., Ravi G., “Earthquake early warning system by IOT using Wireless sensor networks,” 2016 Int Conf on Wireless Comms, Signal Processing and Networking (WiSPNET), 23-25 March 2016, Chennai, India DOI: 10.1109/WiSPNET.2016.7566327 [3] A Laghari, Z A Memon, S Ullah, I Hussain, “Cyber Physical System for Stroke Detection,” IEEE Access, Vol 6, 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National ICT Australia, 2011 [17].A Varga, OMNeT++ user manual version 4.6, OpenSim Ltd, 2014 http://www.omnetpp.org/ (Last accessible 23 Sep 2018) [18].Texas Instruments “CC2420 single-chip 2.4 GHz RF transceiver,” Available [Online]: http://www.ti.com/lit/ds/symlink/cc2420.pdf (Last accessible: 23 Sep 2018) TÓM TẮT PPME GIAO THỨC MAC ƯU TIÊN MỚI CHO MẠNG CẢM BIẾN KHÔNG DÂY ĐA SỰ KIỆN Trong mạng cảm biến không dây đa kiện, nhiều kiện có mức độ ưu tiên khác xuất đồng thời yêu cầu nhiều mức độ ưu tiên chất lượng Trong báo này, đề xuất giao thức MAC PMME sử dụng chế CSMA p-persistent với p thay đổi theo mức độ ưu tiên liệu để giảm xung đột cho khung mang liệu có mức độ ưu tiên khác chế chấp nhận Tx-Beacon sớm để giảm trễ truyền tin mạng cảm biến không dây đa kiện Kết mô cho thấy giao thức đề xuất chúng tơi làm giảm đáng kể độ trễ gói cho tất bốn loại gói có mức ưu tiên khác tiết kiệm lượng nhiều so với hai giao thức MAC có phân biệt ưu tiên liệu QAEE MPQ Hơn nữa, mạng hoạt động dựa giao thức PMME giữ tỷ lệ truyền gói thành cơng cao so với hai giao thức MAC Từ khóa: MAC ưu tiên; CSMA p-persistent; Đa kiện; Mạng cảm biến không dây Nhận ngày 06 tháng 11 năm 2018 Hoàn thiện ngày 24 tháng 12 năm 2018 Chấp nhận đăng ngày 19 tháng 02 năm 2019 Author affiliations: Posts and Telecommunications Institute of Technology (PTIT) *Corresponding author: hangntt@ptit.edu.vn Tạp chí Nghiên cứu KH&CN quân sự, Số 59, 02 - 2019 25 ... Awang, Multi -priority based QoS MAC protocol for wireless sensor networks,” in: Proc 7th IEEE Int Conf Syst Eng and Technol 24 N T T Hang, N C Trinh, N T Ban, PPME – new priority MAC … sensor network. ”... improve multi- event wireless sensor network performance using the novel PMME priority MAC protocol PMME uses two enhancements to improve WSN performance against two previous QAEE and MPQ priority MAC. .. “ERI -MAC: An energy-harvested receiver-initiated MAC protocol for wireless sensor networks,” Int J Distrib Sensor Netw., Vol 10, No 5, pp. 1-8 , 2014 DOI: 10.1155/2014/514169 [12].H Kim and S.-G