Design of QoS-Aware Multi-Level MAC-Layer for Wireless Body Area ...

J Med Syst (2015) 39: 192 DOI 10.1007/s10916-015-0336-x

MOBILE SYSTEMS

Design of QoS-Aware Multi-Level MAC-Layer for Wireless Body Area Network Long Hu1 · Yin Zhang2 · Dakui Feng3 · Mohammad Mehedi Hassan4 · Abdulhameed Alelaiwi4 · Atif Alamri4

Received: 3 November 2014 / Accepted: 7 September 2015 / Published online: 21 October 2015 © Springer Science+Business Media New York 2015

Abstract With the advances in wearable computing and various wireless technologies, there is an increasing trend to outsource body signals from wireless body area network (WBAN) to outside world including cyber space, healthcare big data clouds, etc. Since the environmental and physiological data collected by multimodal sensors have different importance, the provisioning of quality of service (QoS) for the sensory data in WBAN is a critical issue. This paper This article is part of the Topical Collection on Mobile Systems  Dakui Feng

feng [email protected] Long Hu [email protected] Yin Zhang [email protected] Mohammad Mehedi Hassan [email protected] Abdulhameed Alelaiwi [email protected] Atif Alamri [email protected] 1

School of Computer Science and Technology, Huazhong University of Science and Technology, Wuhan, China

2

School of Information and Safety Engineering, Zhongnan University of Economics and Law, Wuhan, China

3

4

School of Naval Architecture and Ocean Engineering, Huazhong University of Science and Technology, Wuhan, China Chair of Pervasive and Mobile Computing, College of Computer and Information Sciences, King Saud University, P.O. Box 51178, Riyadh 11543, Saudi Arabia

proposes multiple level-based QoS design at WBAN media access control layer in terms of user level, data level and time level. In the proposed QoS provisioning scheme, different users have different priorities, various sensory data collected by different sensor nodes have different importance, while data priority for the same sensor node varies over time. The experimental results show that the proposed multi-level based QoS provisioning solution in WBAN yields better performance for meeting QoS requirements of personalized healthcare applications while achieving energy saving. Keywords Healthcare · Body area network · QoS

Introduction In recent years, provisioning of human-centric services through WBAN is continuously attracting extensive attention from both academia and industry. In WBAN, the sensors worn on human body are used as the end devices, as shown in Fig. 1. Typically, the body sensors do not directly communicate with access points (APs), instead, a personal server (PS) is used as the bridge between body sensors and APs [1]. PS can be a smartphone. In addition to routing body signal and sensor data, there are other functions supported by PS, such as 1. data fusion for reducing the size of body signal; 2. acting as the ZigBee network coordinator for the body sensors. Differing from the characteristic of QoS provisioning in wireless sensor network (WSN), WBAN has stricter requirements for specific QoS, including time constraints and reliability [1]. In addition, QoS is required to be

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Fig. 1 The illustration of a typical WBAN architecture during patient care

customized for different WBAN application scenarios. For example, in a typical scenario at hospital where sensory data from different patients are transmitted over limited bandwidth, the transmission priority should be differentiated to provide situation-aware healthcare services. Motivated by the practical situation at hospital, this paper considers the following three levels of priorities for QoS design: 1. priority of user (PoU), indicates that different users have different priorities. For example, the sensory data of seriously ill patients should have higher priority for faster delivery than that of the patients with chronic disease; 2. priority of data (PoD), means that heterogeneous sensory data collected from various sensor nodes (belongs to one user) should have different priorities. For example, electrocardiogram (ECG) data should be sent prior to temperature data; 3. priority over time (PoT), represents the priority of sensory data collected by of the same sensor node may vary over time. For example, the blood sugar data are usually given lower priority; however, if the blood sugar is too high or too low, high priority should be given. Existing work of MAC layer design for QoS provisioning in WBAN are either based on IEEE 802.15.4 non-beacon enabled mode or beacon enabled mode. For example, NDNC-BAN [2] aims to provide QoS by adaptive bandwidth scheduling based on the non-beacon mode in body sensor network. Most of the proposed schemes are based on beacon enabled mode. In [3], the superframe structure in beacon enabled mode is fine tuned to implement the QoS

framework for WBAN with a star topology. In [4], Rahman et al. design ATLAS to dynamically adjust contention access period (CAP), contention free period (CFP), and inactive period (IP) in superframe for QoS provisioning in terms of energy and delay. In [6], a collect-and-send scheme named CoSenS is proposed to overcame the weakness of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) mechanism. However, the above mechanisms did not consider the QoS provisioning of sensory data delivery at multiple levels in WBAN. In addition, most of the proposals are implemented in a star topology based WBAN. This paper proposes a level-based QoS framework based on the IEEE 802.15.4 beacon-enabled mode in WBAN with a tree topology. Compared to the existing work, the contributions of this paper are described as below: –

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QoS mechanism implemented in the tree topology is more applicable for a large-scale network than the star topology. The level-based QoS framework provides guaranteed services in three levels in terms of PoU, PoD and PoT, which is more flexible than a single level-based proposal. In a tree structured network, the router node between terminal node and the coordinator adjusts dynamically according to the instant priority of terminal sensor nodes, which allocates the limited bandwidth for delivering sensory data among different patients who share a single coordinator in a more balanced fashion.

The simulation results verify the effectiveness of the multi-level QoS provisioning in WBAN:

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1. the implementation of PoU guarantees the user with higher priority access the resource of guaranteed time slot (GTS) first; 2. when employing PoD, the dispatcher queue delay is 50 % lower than the case without priority; 3. the use of PoT yields 29 % lower end-to-end delay that without priority.

IEEE 802.15.4 MAC Protocol and tree topology IEEE 802.15.4 Beacon-enabled mode IEEE802.15.4 provides two operating modes: beacon mode and non-beacon mode. In the non-beacon mode, unslotted CSMA/CA mechanism is used for communication, which is simpler than slotted CSMA/CA in the beacon mode, with all nodes access to the channel in a competitive mode. The beacon mode is more applicable to real-time data transmission, periodic data transmission, and the realization of QoS[5] in WBAN. This Paper mainly researches the network communication under the beacon mode. There is a significant concept in the beacon mode: superframe, which is a periodic time structure and divided into active period and optionally inactive period. Every coordinator has its own superframe, with the superframe structure shown in Fig. 2. The coordinator periodically transmits the beacon frame and the node simultaneously runs via the beacon frame. The time interval between two adjacent beacon frames is called beacon interval (BI). During the active period, the node opens the receiver to receive data or prepare to receive data. During the inactive period, the node sleeps to save energy. The duration of the superframe is expressed in SD (Superframe Duration) which is divided into 16 equal aNumSuperframeSlots. The entire active period is also divided into CAP and CFP. During CAP, the node accesses the channel with slotted CSMA/CA. During CFP, the node conducts communication with TDMA (Time Division Multiple Access). The time slot resource is described with Guaranteed Time Slot (GTS). During CFP, there are one or several GTSs and the GTS

Fig. 2 Superframe structure

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assigned to an equipment includes one or several time slots for the communication with the coordinator. BI and SD are separately decided by Beacon Order (BO) and Superframe Order (SO), with the computing method shown in Formula (1) and Formula (2). SO and BO must meet: 0 ≤ SO ≤ BO ≤ 14 BI = aBaseSuperf rameDuration × 2BO SD = aBaseSuperf rameDuration × 2SO aBaseSuperf rameDuration = aBaseSlotDuration ×aNumSuperf rameSlots = 60 × 16 = 960symbols The Slotted CSMA/CA mechanism has three important parameters: NumberofBackoff (NB), Content Windows (CW), and BackoffExponent(BE). Thereinto, NB means the number of backoff, with the initial value of 0 and the maximum value of 4. When the node completes random delay and supervises busy channel, NB is increased by 1; if NB surpasses the maximum value, the transmission fails. CW means content windows, expressing times of channel idleness to be acknowledged prior to data transmission, with the default value of 2. When the channel idleness is acknowledged to be successful once, CW is decreased by 1. When CW is 0 and the network channel is idle, data starts to be transmitted. BE means backoff exponent, expressing the random backoff time prior to the detection of channel idleness, with the value range of 0 5 and the default value of 3. IEEE802.15.4 protocol does not compulsorily but very flexibly set values of NB, BE, and CW with which may be adjusted according to actual conditions. In future, these parameters will be appropriately adjusted to meet QoS demands. During CFP, under IEEE 802.15.4 beacon mode, guaranteed time slot (GTS) is used to provide channel visit for access devices. Before equipments access the channel, GTS must be applied and the frame format of GTS request command is shown in Fig. 3. When the node (End Device or Router) utilizes GTS to transmit data, it must transmit GTS allocation request command frame to its parent node (router or coordinator). In addition, when CharacteristicsType domain in

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allowable maximum address in the network is calculated according to Formula (5). An = Aparent + Cski(d) × Rm + n  Cskip(d) =

1 + Cm × (Lm − d − 1) , Lm −d−1 1+Cm −Rm −Cm ×Rm 1−Rm

Amax = Cskip(0) × Rm + Cm − Rm

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The number of the remaining time slots of the current superframes in the parent node is more than GTS length of node request (inclusive); The number of allocated GTS in the parent mode is less than 7 (7 GTS at most for every superframe); After GTS allocation, the CAP length in the parent node is more than the value of aMinCAPLength (inclusive) (the minimum CAP length provided in IEEE802.15.4, with the value of 440 symbols).

When the bandwidth resource allows, the parent node allocates GTS for nodes in the principle of first-come-firstservice and saves GTS allocation in the GTS domain of the beacon frame. The node which requests GTS analyzes the received GTS domain of beacon frame within a stipulated beacon cycle to judge whether GTS is allocated. If the parent node allocates GTS for itself, it may transmit data within a stipulated GTS time slot scope. Or else, GTS allocation request fails. Tree topology structure Tree addressing is a default address allocation mechanism in ZigBee. During the use of tree addressing, we must specify three network parameters in advance: maximum number of child nodes (Cm ), maximum number of routers in child nodes (Rm ), and maximum network length (Lm ). The depth of a coordinator is provided to be 0, the depth of an address is 0, and the depths of sub-equipments of the coordinator are 1, with length increased by 1 for per next level. When you have determined values of Cm , Rm , and Lm , you may calculate the addresses of leaf nodes (i.e. non-router nodes and coordinators) according to Formula (3) and Formula (4).The

if Rm = 1

Otherwise (2)

Fig. 3 GTS request command frame structure

the command frame is 1, it means GTS application. GTS Length means the number of applied time slots. The parent node transmits acknowledgement frame after receiving GTS request command. When the parent node is allocating GTS, it must meet the following three conditions:

(1)

(3)

Cskip(d) in Eqs. (1–3) and Algorithm (1-2) mean address intervals among sub-equipments of coordinators in the child nodes of nodes of a router with the depth of d. n means the available n terminal equipment with the scope of 1 (Cm Rm ). Amax means the maximum available address number and the number surpassing Amax could not be used. For example, when Cm =7, Lm =5, and Rm =5, the address intervals among sub-equipments of routers in child nodes of a = coordinator is (d = 0) Cskip(0) = 1+7−5−7×55−0−1 1−5 1093. Since Rm =5, there are only five child nodes of routers under the coordinator and their addresses must be R1 =1, R2 =1094, R3 =2187, R4 =3280, and R5 =4373. That is to say, every router may accommodate 1093 descendant nodes. Since Cm =7, there are also two 7 − 5 = 2 terminal nodes under the coordinator and their addresses are calculated to be 5466 and 5467 by the use of Eq.(3). However, we shall notice that the coordinator usually allocates address according to the adding sequence of routers to the network and from small to big, and the coordinator also allocates addresses according to the adding sequence of terminal nodes to the network and from small to big. The maximum address of the network in this example is Amax = 1093 × 5 + 7 − 5 = 5467, and addresses more than 5468 (inclusive) will be wasted. Similarly, we may calculate the address allocation of child nodes of other routers such as R1 . Seen from the above example analysis, we know the tree addressing has the following shortages: 1. address space is wasted, specifically: the address space over Amax is wasted. 2. Since the tree address allocation is a pre-allocation mechanism, during network planning, we shall carefully select the three parameters including Lm , Cm , and Rm . Once such parameters are determined, the equipment addresses are determined and then network topology is also determined. If the network topology structure needs to be changed, it may be easily limited by address space. Therefore, such addressing way is not flexible enough. Tree addressing is characterized with a simple routing algorithm

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and is closely related to the tree routing algorithm. The routing utilized in the tree topology structure is called tree routing or hierarchical routing. In the tree routing, data packets are spread along the tree route and relies on tree addressing. After a router compares the target address with its address, the router may know next-hop node address. In the treeing addressing, the address field reserved for child nodes of a router is calculated with CSkip(d) function. If the target address is not in the address field, it indicates that the node of the target address is not its descendant node and then, next address shall be the parent node of a router. For example, assuming the target address is D, the depth of a router is d, the address of a router is A, when DA or DACSkip(d1), the router transmits data packets to the parent node. If ADACSkip(d1), the data packets should be transmitted to a child node of the router. If D > A + Skip(d) × Rm , it indicates the target node is the terminal child node type of the router and, in next-hop, directly arrives in the target node, or else, the target node is a child node of the router. Since every child node of a router occupies CSkip(d) address field, | [D−(A+1)] CSkip(d) |1 means the address field that the target node belongs to a child node of a router, and in next-hop, the A+1 |×CSkip(d), where |x| address shall be A+1|[D − CSkip(d) means the maximum integer within x. It can be seen that the tree routing is not required to save other infoRm ation except some necessary network parameters, which features simple calculation and is suitable for the low-power consumption application in WBAN.

Level-based QoS framework This section proposes a tree topology structured wireless body sensor network QoS framework, as based on the IEEE 802.15.4 beacon mode. The framework is integrated with the IEEE 802.15.4 beacon-enabled communication mode, and uses tree topology and tree routing. The framework divides the service into three levels, Level I is the service differentiation of patient level, where priority is determined according to the degree of urgency of the patient’s disease or the payment situation, the communication of the high priority patient is guaranteed, and is called the priority of patient. Level II is the priority of the internal sensor of the patient. Generally, the human body carries multiple sensor nodes (e.g. EEG, ECG) in WBAN, these sensor nodes usually have different priorities according to practical situations, for example, the priority of the ECG sensor of a patient with heart disease should be higher than that of other sensors, when the heart disease becomes active, the ECG data must be sent out prior to other sensor nodes. Level III is the priority of data in the sensor node, where the priority of data frames in the sensor node to be sent is differentiated according to the degree of urgency, thus, ensuring important

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urgent data are sent first, for example, when heart disease becomes active, the data information must be sent to the medical center immediately. We use the CAP and CFP in the IEEE 802.15.4 beacon mode to implement the three levels of priority. PoU-based QoS implementation Each patient carries with them equipment called PS, which is in charge of receiving the sensor data of the patient and forwarding the data. The PS has the tree routing function. In medical application, some sensor data of some patients should be transmitted first, thus, the priority of data is differentiated. For example, in urgent medical treatment, the data of seriously ill patients are given higher transmission priority. Two digits are used in the Reserved for GTS Characteristics field, as shown in Fig. 3, to designate the priority of data, which can designate 00˜03 priorities. The medical care personnel set the priority of node or router according to the physical circumstances of the patient, when the node applies for GTS, priority is set in the Reserved field. When the father node (router or coordinator) receives a GTS request, it is inserted in the GTS queue according to the priority of Reserved requests. The parent node GTS queue is in ascending order of priority. The GTS is allocated from the end of queue to the front, as shown in Fig. 4. When inserted in the queue, the father node reallocates the GTS in descending order of the GTS queue priority, thus, the low priority GTS may lose the time slot, and the GTS without a time slot becomes ”Waiting GTS”, which waits for the high priority GTS to release the time slot resource. When the high priority GTS node releases GTS, the father node reallocates GTS, and the following ”Waiting GTS” may recover the time slot resource. In the tree structure, when the node priority under the router is changed, the priority of the router is changed accordingly; the priority of the router is the weighted average of various subnode priorities. The steps are detailed below: 1. The terminal node sends a GTS request to the router; 2. The router returns an ACK frame to the terminal node;

Fig. 4 GTS queue schematic diagram

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3. The router allocates time slot to the terminal node, and updates its priority; 4. If the router priority changes, a new GTS request is sent to the coordinator; 5. If the router has allocated GTS, the coordinator updates its GTS information, otherwise the coordinator allocates a GTS time slot according to router priority; 6. The router sends a beacon frame with new allocation information to the terminal node; 7. The coordinator sends a beacon frame with the new allocation information to the router; When the terminal node receives the beacon frame, it stops sending data if its GTS initial time slot is -1, till GTS is reallocated to the beacon frame (initial time slot is not -1) before data transmission. When the router priority is changed, a new GTS request is sent to the coordinator, which updates its GTS queue according to the priority of the router, and then, notifies the router via the beacon frame, where the processing procedure is similar to the router. PoD-based QoS implementation There may be multiple sensor nodes (e.g. EEG, ECG) on the human body. There are two methods for QoS implementation between sensor nodes: the first is the Backoff Exponent (BE) of CAP in the time slot-based CSMA/CA mechanism. The second is the GTS mechanism of CFP, which function has been integrated into the PoU-based QoS implementation. The first method is specified, as follows. The BE represents the random backoff waiting time of the node when the detection channel is in the busy or idle state, its value is set according to the battery life extension parameter macBattLifeExtPeriod. If this attribute value is TRUE, BE=min (2,macMinBE), i.e. the minimum value between 2 and macMinBE. If this attribute value is FALSE, BE=macMinBE. As the replacement of the node battery in the body area network is relatively easy, we assume the macBattLifeExtPeriod attribute value to be FALSE, which is to say, the value of macMinBE is the value of BE, where T represents the random backoff waiting time, and R represents random integers within 0 ∼ (2BE − 1). It is obvious that the selection of the BE value directly influences random backoff time T, the range of BE is 0˜macMaxBE, and the value of macMaxBE is 0˜5. A smaller BE value means the equipment is more likely to use the channel to send data first. Thus, it can be seen that if the nodes have different BE’s, they have different chances of occupying the CSMA/CA mechanism access channel. We implement the service differentiation by regulating the BE value of each End Device, where a smaller BE represents a higher priority of the End Device, thus, guaranteeing QoS in the CAP.

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PoT-based QoS implementation There are multiple types of data to be sent inside each sensor node, such as, periodically sent nonurgent data, urgent data of accident, data requiring confirmation, data not requiring confirmation, and the command frame of the MAC layer. In order to ensure urgent accident data can be sent successfully and immediately, service differentiation is required for the data to provide QoS assurance. When the data flow forms in the node, the internal processing program sets the priority according to the data type, and then adds the data in the CAP dispatcher queue, if the queue is empty, the data is directly added in the queue. If the queue is not empty, the data packet is inserted in the queue according to the priority of the data packet, where data packets with high priority are ranked in front of data with low priority to be sent first.

Performance evaluation The performance of the proposed QoS framework and implementation algorithm is evaluated by computer simulation. The OPNET Modeler simulation tool [7] and IEEE 802.15.4/ZigBee OPNET simulation model of open source code [8] are used. The proposed level-based QoS framework and algorithm are implemented. The tree routing algorithm in the simulation model is modified to meet the QoS requirement, and the GTS scheduling algorithm supporting QoS is added.

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BE-based QoS simulation If the patient carries three sensor nodes, the three sensor nodes must communicate with PS. There are two cases of BE values for the three sensor nodes, node 1, node 2, and node 3: Case I, the BE values of three sensor nodes are 3; Case II, the BE values of three sensor nodes are 1, 2, and 3, respectively. The three sensor nodes have the same flow start time in the CAP, the flow rate is set as 100 bits/0.03s, and the simulation time is 50s. The CAP queue delay time

Fig. 5 The CAP queue delay time simulation results

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simulation results of two kinds of BE values are shown in Fig. 5a and 5b. When the nodes have identical BE values, the delay time of the data to be sent by the three nodes in the queue centers at 0.005s˜0.010s. When different BE values are set, the queuing delay of node 1 is 0.003s˜0.004s, the queuing delay of node 2 is 0.006 s˜0.008 s, and the queuing delay of node 3 is 0.008s˜0.012s. The simulation results show that the delay in the data transmission of the three nodes increases with the BE value, which implements the effect of sending data according to priority.

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Fig. 6 Network load simulation results

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GTS-based QoS simulation Six subnodes are set under one router, the BO is set as 6, the SO is set as 2, the interval between subnode packets is 1s, the packet size is 500 bit, and the simulation time is set as 60s. If four nodes apply for the same GTS priority before modification, node1˜node6 apply for four time slots, the simulation result is as shown in Fig. 6a. It is observed that, according to the FCFS principle, node1 to node3 have obtained four time slots, as limited to minimum CAP, the CFP can be divided into 13 time slots at

10

most, node4 obtains one time slot, and as there is no available time slot when node5 and node6 apply for time slots, they always fail in application. When the GTS allocation algorithm is improved, the simulation result is shown in Fig. 6b, and the variance in the GTS queue of router in the simulation process is shown in Fig. 7. Figure 7 shows the family diagram of the variation of the father node GTS queue, with the start and end of data transmission of node5 and node6 (16th sec-50th sec), when node4 begins to send data. When node4 applies for a GTS time slot, it is allocated with four time slots first, and node2

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Fig. 7 Change of the GTSs’ priority

and node3 occupy four time slot, respectively, as node2 has the lowest priority, it has only one time slot. The GTS queue is shown in Fig. 7a. When node5 has applied for four time slots at the 20th second, node2 is deprived of GTS and enters the waiting state. Figure 6 shows that the network output load of node2 becomes smooth at the 20th second, and node1 has only one time slot. The GTS queue is shown in Fig. 7b. When node6 has applied for four time slots at the 24th second, node1 is also deprived of GTS and enters the waiting state. The GTS queue is shown in Fig. 7c, and the network output load of node1 in Fig. 6 becomes smooth. Node5 reaches the end time at the 40th second and releases GTS, and node1 recovers one time slot GTS, the GTS queue is shown in Fig. 7d. The network output load of node5 in Fig. 7 becomes smooth, node1 begins to send data again, and the network output load begins to rise. Node6 reaches the end time at the 50th second and releases GTS, node1 has three additional time slots, and thus, it has four time slots. Node2 recovers one time slot in GTS, and the GTS queue state is restored to Fig. 7a, which increases one time slot in GTS, the GTS queue is shown in Fig. 8 Change of the routers’ priority

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Fig. 7d. The network output load of node6 in Fig. 6 becomes smooth, node2 begins to send data again, and the network output load rises. The aforesaid results prove that we have implemented resilient transmission of data with different GTS priorities in CFP. The priority of the router is the weighted average of all GTS time slot priorities, and when the GTS queue changes, the priority of router changes accordingly. The priority of the router is shown in Fig. 8. If the router priority changes, a GTS assignment request is sent to the coordinator. As the priority of node1 and node2 is 1 at the 4th and the 8th second, there is no change. When node3 begins to apply for GTS at the 12th second, the average priority of the router is 1.3, when node4˜node6 begin to apply for GTS, the average priority approaches to 3. When node5 and node6 quit GTS at the 40th and the 50th second, the average priority is a little lower than 2. According to Algorithm 2, the total number of time slots is 13, the router priority is (4*3+4*2+4*2+1*1)/131.9, meaning the change in the priority of node results in changes in the priority of the router. Simulation of QoS in node At Algorithm 2, ← denotes an assignment operation. As the settings of QoS in the node and data transmission are only related to the sensor and PS, in order to simplify the setting process and analyze the simulation result, we set only one sensor node for communication with the PS. As the ratio of MAC command frames to the overall communication is low, we only simulate ACK and NO ACK flows. The ACK and NO ACK flows of the sensor node are sent at intervals of 0.01s (exponentially distributed), the data packet size is 100 bits, the transmission time is 0.2s˜4.0s, and the simulation time is 5s.

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Fig. 9 The end to end delay time simulation results

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The simulation result of the average End to End Delay of data frames without priority is shown in Fig. 9a. The simulation result of priority is shown in Fig. 9b. The average End to End Delay of ACK flow and NACK flow, without priority, centers at 0.007s˜0.009s; when priority is set, the average ETE delay of the ACK flow centers at 0.004s, and the average ETE delay of the NACK flow centers at 0.014s˜0.018s, meaning priority setting guarantees preferential transmission of ACK data to the destination.

Conclusion Providing effective QoS assurance mechanism in the body wireless sensor network is very important for the popularization of WBAN. This study used IEEE 802.15.4 beacon mode and the tree routing based on tree topology to implement the level-based QoS framework, ensuring the transmission of data with high priority at three different levels. It is completely compatible with the existing communication

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protocols while the QoS is implemented, and the proposed QoS framework is validated by computer simulation. Acknowledgments This work was funded by the National Plan for Science, Technology and Innovation (MAARIFAH), King Abdulaziz City for Science and Technology, Kingdom of Saudi Arabia, Award Number (12-INF2885-02).

References 1. Chen, M., Gonzalez, S., Vasilakos, A., Cao, H., and Leung, V.C.M., Body area networks: A survey. ACM/Springer Mobile Networks and Applications 16(2):171–193, 2011. 2. Chen, M., NDNC-BAN: Supporting rich media healthcare services via named data networking in cloud-assisted wireless body area networks. Inf. Sci. 284(10):142–156, 2014.

Page 11 of 11 192 3. Cao, H., Gonzalez, S., and Leung, V., Employing IEEE 802.15.4 for quality of service provisioning in wireless body area sensor networks. In: Proceedings IEEE advanced information networking and application, AINA, 2010. 4. Rahman, M., Hong, C., Lee, S., and Bang, Y., ATLAS: A traffic load aware sensor mac design for collaborative body area sensor networks. Sensors 11(12):11560–11580, 2011. 5. Lai, C., Wang, H., Chao, H., and Nan, G., A network and device aware Qos approach for cloud mobile streaming. IEEE Trans. Multimed. 15(4):747–757, 2013. 6. Nefzi, B., and Song, Y., QoS for wireless sensor networks: Enabling service differentiation at the MAC sub-layer using CoSenS. Ad Hoc Netw. 10(4):680–695, 2011. 7. Chen, M.: OPNET IoT simulation. Huazhong University of Science and Technology Press. ISBN 978-7-5609-9510-6, 2015. 8. OpenSource Toolset for IEEE 802.15.4 and ZigBee. Available: http://www.open-zb.net/.