50120140501017

International Journal of Computer Engineering and Technology (IJCET), ISSN 0976INTERNATIONAL JOURNAL OF COMPUTER ENGINEERING &
6367(Print), ISSN 0976 - 6375(Online), Volume 5, Issue 1, January (2014), © IAEME

TECHNOLOGY (IJCET)

ISSN 0976 – 6367(Print)
ISSN 0976 – 6375(Online)
Volume 5, Issue 1, January (2014), pp. 153-161
© IAEME: www.iaeme.com/ijcet.asp
Journal Impact Factor (2013): 6.1302 (Calculated by GISI)
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IJCET
©IAEME

LOCATION BASED STORE AND FORWARD PACKET ROUTING
ALGORITHM FOR WIRELESS BODY AREA NETWORKS: A SURVEY
Shivam Wadhwa1,

Kusum Dangi2

1

2

Dept of Computer Science and Engineering, ITM University Gurgaon, India
Dept of Electronics and Communication Engineering, ITM University Gurgaon, India

ABSTRACT
The increasing use of wireless networks and the constant miniaturization of electrical devices
have empowered the development of Wireless Body Area Networks (WBANs). WBAN is an
application of Wireless Sensor network that is used in health monitoring. Wireless sensor nodes are
either placed inside or on the body and transmit the data in form of packets .Packet Routing is very
crucial technique in WBAN. Packet Routing is used to send the data which is being monitored by
various sensor nodes implanted on the body. In this paper we discuss about location based store-and
forward packet routing algorithm for WBAN with general body postures.
Keyword: Communication Architecture, Location Based Routing, Packet Routing, QoS, WBAN,
WPAN.
1. INTRODUCTION
WBAN consists of tiny sensors attached or implanted in the body which are capable of
establishing a wireless communication link. The on body sensors continuously monitor the human
physiological changes occurring periodically. This physiological data is in form of packets that are to
be sent to the destination. In this paper we will discuss about various aspects of WBAN and on-body
store-and forward packet routing algorithm for WBAN.
2. WIRELESS BODY AREA NETWORK: OVERVIEW
WBAN technology came into existence around 1995 with the idea of using Wireless personal
area network (WPAN) which help in communication on or around the human body[1,2].

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International Journal of Computer Engineering and Technology (IJCET), ISSN 09766367(Print), ISSN 0976 - 6375(Online), Volume 5, Issue 1, January (2014), © IAEME
2.1 Types of Devices
(Wireless) Sensor node: A Sensor node is a device whose function is, gathering and
responding to any kind of physiological change, happening in the human body and reports this data
with wireless means.
(Wireless) Actuator node: Its function is to act according to the data received from the
sensors.
(Wireless) Personal Device (PD): Its function is to inform the patient about all the
information gathered from the sensors and actuators.
3. WBAN COMMUNICATION ARCHITECTURE
WBAN posse’s three tier communication architecture

Figure1: Three tier communication architecture
In fig.1, a three-tier architecture based on a BAN communication system is shown. The figure
shows that all the sensors send their data to the personal server and finally the data is streamed to a
medical practioner. The whole communication takes place in three-tier:
3.1 Tier1-communication
In Tier-1, the communication occurs around 2 metres of the human body which comprises of
two actions first is the communication between the body sensors and the other is the communication
between the body sensors and portable personal server.
In Tier -2, the communication occurs between the personal server and the access points. The
basic functionality of this tier is interconnecting various BANs with various networks.
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In Tier-3, the communication is intended for metropolitan areas. It is used to bridge the
network for inter- BAN and beyond- BAN communication.
4. SENSORS USED IN WBAN
Accelerometer/Gyroscope: Accelerometer sensor is used to monitor the various body
positions like walking, sitting, standing. . The accelerometer-based posture monitoring for BANs are
used to measure the vibration happening in the human body and also acceleration due to gravity.
Gyroscope uses the principle of conservation of angular momentum to measure or maintain the body
orientation.
Blood glucose: The amount of glucose circulating in the blood is called as blood glucose. It is also
called as blood sugar. Glucose is measured by extracting blood from the finger and then applying it
to a test strip composed of chemicals sensitive to the glucose in blood sample. An optical meter
(glucometer) is used to analyze the blood sample and gives a numerical glucose reading.
Blood pressure: The blood pressure sensor uses the principle of oscilimetric to measure the blood
pressure of the body.
CO2 gas sensor: This sensor is used to measure the changes in carbon-dioxide happening in the
human body.
ECG sensor: ECG is also known as electro cardio gram that is used to record the electric activity of
the heart which is helpful in diagnosing a heart disease. ECG signal is obtained by placing several
electrodes on the skin (e.g., arms, and chest), and then measuring potential differences between these
electrodes.
EEG sensor: Electro encephalogram sensor is used to measure the electrical activity happening
inside the brain. It is done by attaching tiny electrodes to the human’s scalp at multiple locations.
The information that is sensed by the electrodes is forwarded to an amplifier for producing a pattern
of tracings.
EMG sensor: EMG sensor is used to measure the electric signals produced by the muscles. Nerve
conduction is usually done to measure the electrical activity in muscles as nerves control the muscles
in the body.
Temperature and Humidity sensor: The temperature and humidity sensors are used to measure the
temperature and humidity of the environment around the human body.
5. PACKET ROUTING IN WBAN
Packet routing is important aspect in Wireless body area network .A number of small sensors
as discussed above strategically placed on human body can create a Wireless Body Area Network
which can monitor vital signs and collect the data in the form of packets. This data movement across
such sensors can be point to point or multi-point. In this section we will discuss on-body packet
routing issues in case of various body postures [3].

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Goal of packet routing: The goal of this discussion is to develop on-body store and forward packet
routing and minimising end-to-end packet delay by dynamically choosing routes on which the
storage delay is low. The main goals of this packet routing are: 1.) end-to-end delay, 2.) packet loss,
and 3.) transmission energy consumption.
In fig.2, various sensors are placed on the human body that will transmit the data to a sink
node which in turn will send the data to the sink node which in turn communicates with the out of
body server.
Two store and forward routing algorithms have been developed based on location based
routing protocol.
5.1 Relative Location based Forwarding (RLOCF)
The main logic of packet forwarding in RLOCF is that a node forwards a packet to other
neighbouring nodes that are known to be closer to the sink node. The main logic behind this
forwarding algorithm is to give information to every node about the relative distances between all
other neighbouring nodes in the network and the sink node. It can be easily implemented on typical
on-body networks (as shown in Fig.2) containing only a few nodes. The packet forwarding logic in
RLOCF can be formally stated as follows.
For an M-node body sensor network, a sorted list [n1, n2, ni,. .,nM] is created based on the
distances of the individual nodes from the sink node (e.g. node-6 in Fig. 1). Node n1 represents the
sink, and the nodes are placed in the list such that: d(n1) =0 or 1 and d(ni) ≤d (ni+1) , i = 1, 2, 3, …,M1, where the quantity d(ni) represents the distance of node ni from the sink node n1.Based on the
known sensor placement locations and the usual body configurations, the quantities d(ni) are first
estimated manually and then the above sorted list is created.

Figure 2: Body Area Sensor Network
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RLOCF packet forwarding logic at node-i
for (j = 1; j ≤ i-1; j++){
if ( Li,j = 1){
// if link Li,j is now connected
Forward the packet to node-j;
Break;
}
}
if (the packet is not forwarded)
Buffer it at node-I;
// Execute the above logic every time nodei receives a
// new packet to be forwarded OR it has
buffered
// packets AND a new link Li,k (for all k =
1, 2, …, M
// except k = i is formed

In the Figure2, node-6 is considered as the sink, the sorted list can be evaluated as [6, 7, 4, 5,
1, 2, 3 ]. The packet forwarding logic for node-i is to forward a packet to node-j, where node nj is the
first currently connected node in the sub-list [n1, n2, ni-1] in that order.
In other words, the packet is forwarded to a node which is nearest to the sink node among all
the currently connected nodes that are closer to the sink than node-i itself. If there is no single node
that is closer to the sink is c connected, node-i continues buffering the packet till the connectivity
status changes, which is when the above logic is again executed for finding an appropriate node to
which the packet can be forwarded. Relative LOCation based Forwarding (RLOCF) logic gives an
option of multiple possible next hops. The advantage of the above forwarding logic is that in addition
to ensuring that a packet is always forwarded closer to sink node, it can enjoy the phenomenon of
expedited forwarding when nodes that are very close to the sink are directly in touch with a
forwarding node This feature improves both packet delivery delay and hop-count performance of the
routing.
Relative Location based Forwarding (RLOCF) logic has been described for a multi-point-topoint application in which all the nodes present on the body send their packets to a single sink node.
The same logic can be further expanded for multi-point-to-multi-point applications. In multi-pointto-multi-point applications case, instead of a single list, each node maintains M-1 separate lists for
each other node.. The same forwarding logic can then be applied using the appropriate list for the
node which a packet is destined towards.
5.2 On-body Store and Flood Routing (OBSFR)
A modified flooding protocol has been implemented i.e. the On-body Store and Flood
Routing to determine the best case delay performance. . In the case of flooding mechanism multiple
copies of a single packet are dispatched and they reach the destination via multiple routes and the
first arrived copy to reach destination indicates the minimum possible end-to-end delay that can be
achieved by RLOCF.
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Mechanism:
In this flooding mechanism a packet carries a unique identifier {source_id. seq_no.} and also
carries a list of node-ids that indicates its path from the source node. When a node-i receives a packet
for the first time (detected from its unique identifier), the pack is buffered there till it encounters at
least one node which is not present in the list of node-ids found in the packet. When it encounters
such a node the packet is handed over to that node and is deleted from its own buffer.
If the packet is subsequently received by the same node-i then it will be ignored. The main
benefit of this flooding protocol. The main benefit of using this approach is reducing the number of
packet drops. Now let us assume a situation in conventional flooding (i.e. without using the list of
node-ids) node-i broadcasts the packet to node-j which already had that packet and it already had
broad cast forwarded the same packet then it simply will discard it after receiving from the node-i. If
node-i and j are forming a network partition that does not contain the destination address then that
packet is dropped from the partition.
The OBSFR mechanism for a multipoint-to-point implementation is summarized in the
pseudo-code in the following algorithm:
OBSFR logic:
Process followed at node-i that forward packets to sink-d
while (true){
for(all buffered packets to be forwarded to node-d){
for (all node j [ j∈vN, j ≠ i ]){
if ( Lti,j = 1 and j∉list of node _ ids in packet ){
// j is a neighbor of i, and the packet did not vist node-j before
Broadcast the packet;
Remove it from node-i’s buffer
Break; // done with this packet forwarding
} else
Continue buffering the packet at node-i;
}
}
}
Process for node-i after receiving a packet
{
if ( the packet was not received before)
if (this is not the destination)
Buffer the packet in for further forwarding;
else
Discard the packet; // it was received before
}
In the modified flooding that used the list of node-ids, However, with the modified flooding
that uses the list of node-ids, node –i will broad cast the packet to all nodes that are not present in the
list of node-ids carried by the packet so node –j will not receive this packet as it is not present in that
list. So the buffering continues till it is not able to find such a node. This improves the chance the
packet is forwarded to the nodes that are out of this partition. Hence, it reduces the overall packet
loss probability. But this technique is applicable only to network having lesser nodes and not for
those networks that contains large number of nodes.
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Partition Packet Saturation:
In the above flooding modification there exists a partition packet saturation in which due to
some scenario a packet may have a chance to get lost. Consider a scenario that node-i receives a
packet and it is into a partition with two other nodes p and q such all of them is inter-connected. Now
node-i broadcasts the packet to other nodes p and q as they are not present in the list of node-ids of
the packet and delete it from its own buffer. Now, the nodes p and q broadcast the packet to each
other and as they are not appearing in each other copy of the packet i.e node q does not appear in the
list of p’s copy and node p does not appear in the list of q’s copy of the packet. After forwarding the
packet they will delete from their own buffer, eventually causing the packet to be dropped from the
partition and it will not be able to reach its destination
Goal of On-body Store and Flood Routing:
Inspite of all this On-body Store and Flood Routing (OBSFR) ensures the successful flooding
of the packet to reach the destination with minimum packet delivery delay. But the transmission
energy cost of OBSFR is significantly larger as compared to RLOCF.
6. RADIO TECHNOLOGIES
To have communication possible between the various nodes radio technologies are used. In
this section there is a list of radio technologies are used for BANs and WPANs such as Bluetooth,
Bluetooth Low Energy (Wibree) and ZigBee (IEEE 802.15.4.)[4,5,6].
6.1 Bluetooth
For short range wireless communication Bluetooth technology was designed which was
further used for
connecting various portable devices. These devices support data and voice
application. The current Bluetooth standard in operation is version 2.0 that supports data rate of
3Mbit/s.
6.2 Bluetooth low energy technology
In 2004 Nokia introduced a new technology for providing ultra-low power consumption and
cost which was popularly known as Bluetooth Low End Extension (LEE), and which was later
recognised by the name of Wibree. It was designed to connect small devices to mobile terminals
wirelessly.
This technology provides a data rate of 1 Mbps and uses a simpler protocol stack and focus on shortrange, star-configured networks.
6.3 ZigBee( IEEE 802.15.4)
After the existence of Bluetooth and Wibree a new radio standard was introduced known as
Zigbee (IEEE 802.15.4) that supports low power consumption and is a cost-effective technology.
Zigbee operates in two modes: (1) beacon enabled and (2) non-beacon enabled modes.
(1)Beacon enabled mode: In a beacon enabled mode, a structure of super frame is used which is
divided into two portions: active and inactive. During the inactive portion, devices enter a low-power
mode. During the active portion it has two periods’ contention access period (CAP) and contention
free period (CFP). If any device wants to communicate during the CAP period it competes the other
devices using a slotted CSMA/CA mechanism, while in the CFP it has no contentions and has
guaranteed time slots.
(2)Non –beacon enabled mode: This mode is used if a coordinator does not prefer to use the
beacon-enabled mode, so it will turn off the transmissions and it will use unspotted CSMA/CA
algorithm.
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7. QUALITY OF SERVICE IN WBAN
The sensor nodes and human body should be compatible so that no adverse effects or reaction
should occur. Quality of service is sometimes supported by prioritized QoS. Prioritized QoS first
categorizes the services into different Access Classes (ACs), like real time, non real time, best effort,
etc. Different priority is assigned to each of the access classes. Higher the priority is, higher will be
the chance to access the channel .However, once the priority is set, it remains unchanged on this
approach. In WBAN the level of criticality of QOS parameters vary from application to application
depending upon the situation. In normal day life ECG reading is given more preference over the
body temperature so is assigned a higher priority. But in abnormal situation when the body
temperature is high the priority needs to be interchanged.
8.

APPLICATION OF WBAN

Wireless body area network are a great boon to the modern science and technology. Due its
large number of application such as:
8.1 Medical usage
Hospitals and health care have been the two areas where this technology has been developed
and had a great impact. This technology has a great application in monitoring the patient’s health
condition continuously over a period of time. Several nodes are placed at the most appropriate
position of the human body which actually test its specific parameter. Doctors could really make
diagnosis based on the information gathered over a period of time.
8.2 Sports usage
Wireless body area network has a great use in the life of a sportsperson who are young, who
exercise a lot and who need to have accurate and constant information about their training progress.
In this nodes placed at different area of the body could give different type of information. The
sensors may be the heart sensor, temperature sensor etc. that perform their corresponding function.
8.3 Other usage
There are various areas that could use WBAN technology such as it is used as a modern
solution on the areas of war conflicts. It is possible that the commercial standard will give it more
possibilities and performance.
9. CONCLUSION AND FUTURE SCOPE
From this paper we can conclude that WBAN is a promising technology that can have a great
impact on health care in the future. In this paper we have discussed about what is wireless body area
network, what are the devices involved in WBAN, BAN communication architecture, sensors used
on human body, packet routing, quality of service, applications of Wireless body area network.
Despite advances in the above areas there are many challenges that need to be addressed such
as energy efficient communication protocol, interoperability between BANs and design of successful
applications. Packet routing uses the mechanism of forwarding the packet based on relative node
distances from on-body sink node. It is proposed that with the help of successful leveraging of the
node location, it could provide better routing delay performance.

160

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